Tuning Guides

BMC Mini 998cc Engine Rebuild

BMC Mini 998cc Engine Rebuild

The brief with this engine was to tune to produce similar power to the 1275cc engine. The target figure was 60 bhp with 55 lb ft torque and with a young driver / owner our budget was very tight. Read below how we did it!


Crankshaft: Ground & balanced

Flywheel: Lightened & balanced

Conrods: Lightened & balanced with ARP rod bolts

Pistons: 998Std flat top – balanced

Cylinder Block: Refaced to bring pistons flush with the block face

Camshaft: Performance 285 set at 103 full lift, Single chain retained with offset key

Cylinder Head:

  • Inlet Ports Slight polishing by seat area
  • Exhaust Ports Material removed throughout port area to match
  • LCB exhaust manifold
  • Hardened exhaust valve seat Inserts fitted + 3 angle seat cutting
  • Cylinder head reface – to achieve 11:1 compression ratio
  • Compression tested at 200psi
  • Standard rocker arm assembly
  • 12G295 casting , standard valves

Carb: Single 1 with good ram pipe

Wheels and Diff:? The car came with 13″ wheels. Therefore a 3.9:1 diff was installed.


What a Fun Car! Its high compression and very light internals makes for a very responsive engine.

With a good torque value there are no flat spots. The power curve with HP is clean and achieves 8,000rpm very easily.

Mini Summary

Mini Torque Graph

Mini BHP Graph

Ford Taunus-Cologne V4/V6 Tuning Guide

Ford Taunus-Cologne V4/V6 Tuning Guide

Originally known as the Ford Taunus, this engine is now more commonly known as the Cologne. There are two major forms of Cologne V6 of true concern, basically, the 2.8 and 2.9 series of engines.

Both of these have their roots in Germany – hence the name! In that country, a V4 of the same format was also produced in 1183cc, 1288, 1305, 1498 and 1699ccs. Their V6 series also included 1812cc, 1998, 2293, 2551 and 2792cc. However, the engines that are really only used for power are the UK-supplied versions, 2.3 litre and the aforementioned 2.8 and 2.9.

The 2.3 and 2.8 are significantly different since they feature Siamese ported heads, fibre-teeth cam gear and shorter stroke. In contrast, the 2.9s cam is chain driven in the opposite direction and features 3 port heads.

In practical terms, you either tune one engine or the other – you can’t fit 2.9 heads on a 2.8 because the cam phasing is different amongst many other parts – conversion is therefore very difficult. However, you can fit the 2.9 crank in a 2.8 block although the nose at the front will need machining to accept the cam drive. Neither engine has anything in common with the Essex type V6, which this engine replaced for emissions reasons.

You are likely to find a 2.8 in MkII Granadas, Capri 2.8 Injections and Sierra XR4i, whilst the 2.3 was fitted again to MkII Granadas, plus MkIV/V Cortinas. 1989 saw the switch to 2.9 for the new Mk3 Granadas, whilst the 2.3 became the 2.4. These engines were controlled by twin plenum EFi with Ford EEC IV management. The previous engines had Bosch K-Jet injection/carburettor. However, early Mk3s were fitted with 2.8s along with EFi. The 2.9 also formed the base for the 24 valve Cosworth 4 cam version fitted to the Scorpio.

These engines are very smooth and do rev well although it’s easy to over-rev them too. For this reason most engines feature rev limiters although the Capri’s is safe to 6,000rpm. Since the con rods are the weak link, HD ARP con rod bolts are essential for over 6000 rpm. A con rod that has been stress relieved and shot peened can rev safely to 6500 rpm. An electronic rev limiter is a must have for any engine not fitted with one to prevent the consequences of over-revving. 2.8s are better catered for in terms of cams and heads. Our Stage 1 heads with a Kent V6T1 cam will give power to around 165bhp, whilst Stage 2, or better still Stage 3 with bigger valves, plus a V6T3 cam should see close on 200bhp. We can do 2.9 litre heads to order and, coupled with the relevant Kent cams, you should see at least 10 BHP up on the 2.8, all round. The most significant improvement you’ll see in this engine though is torque – 2.9s behave much more like the old Essex.

Capacity can be increased with a 1mm overbore, which is safe – you can go higher, but overheating is risked beyond this. Use of our Accralite 94mm Pinto pistons are popular in this application although they do need machining to fit. We can supply Farndon H-section steel rods to special order only.

As far as induction goes, the injection can be tuned on the rolling road to cope, although plenty switch to carbs, using the 2.3/2.8 carb inlet manifold.

Ford SOHC (Pinto) Tuning Guide

Ford SOHC (Pinto) Tuning Guide

Introduced by Ford in 1970, the Pinto was one of the first production engines to carry the cam on top of the head, driven by a toothed belt.

There are two main versions – Cortina / RS2000 and Sierra. The latter was mostly unleaded.

The Pinto was manufactured in Cologne and was naturally fitted to many German cars such as the Taunus, including the 1293cc version also fitted to early Sierras. The most common to us are the 1593 and 1993cc derivatives. A 1796cc version was introduced in mid-life Sierras and an E-Max 1.6, introduced in 1984, sharing the 1.8 and 2.0 litre rods.

You’re likely to find a Pinto in Mk3 / Mk4 / Mk5 Cortinas, Capris, Mk1 / Mk2 Escorts, Granadas and Transits. All engines have a rear-bowl sump with the RS2000s being alloy.

The engine is crossflow type with the carb on the right, exhaust left (when viewed from the front). Cam geometry can be a problem so it is recommended to use a complete kit to ensure components match, such as the ones we stock by Kent. The non 2 litre engines are particularly troublesome in this area so we wouldn’t recommend fitting anything more than a base, mild / fast road cam in these. A new spray bar is also valuable insurance on any engine.

As usual, the 2 litre is the tuners favourite with the 205 Injection block being the most suitable base – these are better at taking the maximum re-bore of 93mm and are most suited to 2.1 litre conversions. Cortina blocks usually have the capacity in small numbers on the side – 16 and 20 respectively. Later Sierra blocks have 165, 185 and 205. The early Cosworth YB also used a selected 205 block.

It is fairly common to use 2.8 V6 pistons coupled with a 93mm bore but traditionally, machining is involved – the block needs decking, whilst the rods need the small ends narrowing. We stock Accralites especially for this purpose, which removes the need for additional machining.

Skimming can raise compression to a 10.5:1 maximum and beyond this you’ll need forged pistons, to a safe 12.0:1. It is best to check the size of the combustion chamber on any used head by having it cc’d first. This not only guarantees the compression but can also help with checking the valve to piston clearance too, which can be an issue with previously skimmed heads.

The Pinto’s crank is able to out-rev the rods, which can be a weak link – 7500 is the absolute maximum we would recommend, although this really only applies to the later wider injection rods, which are stronger than the early type.

The 2 litre heads have massive ports to start with so good gains can be had by merely fitting a Kent FR32. Even the best standard Pinto carb a 32/36 DGAV twin choke, is enough to power the engine to 135bhp. Our Stage 1 heads, suitably set up, will reach these levels and feature proper valve guides in place of the standard cast-in type and raised compression. All our heads can be ordered ready converted to run on unleaded fuel.

After this level, the next step is side draughts and it’s best to go straight to 45 DCOEs since the inlet ports are huge. 44 IDF down draughts are a good alternative, but they are much more expensive.

Add a Kent FR33 and our stage 2 head and you should see 150-155bhp. Beyond this and you’re into fast road bordering on race, which means, depending on carb size – 48s and even 50s – you should be seeing an easy 185-200bhp, plus.

At this level, we would only recommend steel components for reliability because you’re on the limit of standard type components. We stock Farndon Cosworth YB cranks for this purpose, which is essentially the same except that it carries a 9 bolt flywheel fixing instead of the standard Pinto bolt pattern. We also stock special Pinto 9 bolt flywheels to match. However, on this point, if you use a Pinto crank it is advisable to have it double-dowelled for safety – it can shear! We also stock std length steel H-section conrods to match this crank as well as YB length rods which are 1.5mm longer.

A great engine with loads of potential.

Ford Lotus Twin Cam 8v Tuning Guide

Ford Lotus Twin Cam 8v Tuning Guide

The stuff legends are made of, the Lotus TC was THE engine of the Sixties, especially in cars such as the Ford Mk1 Cortina plus the Anglia, which was the first road-type car, albeit in prototype form, to carry the motor. Images of Jim Clark belting round a race track cocking a front wheel go hand in hand with this unit.

There are basically two Ford-derived Twin Cams, the Mk1 introduced in the Mk1 Cortina in 1963, and MkII, which was fitted in the MkII Cortina Lotus from March 1967 – this version was also fitted to the 1968 Escort Twin Cam. This is actually the better engine since it has a purpose-cast Lotus block (identified with a large L on the side but usually under an engine mount) as opposed to a mere graded Cortina 1500 block. As such, the engine was based on a Ford Pre-Crossflow with a Harry Mundy-designed, twin cam alloy head, with chain drive and eight valves.

Blocks were bored to 82.55mm from the Pre-Crossflows standard 80.96mm – hence the Mk2 having a thicker casting to more reliably carry the increased capacity that allowed 1558cc. These engines also had square mains caps – the same as 711M Crossflows, proper oil seals as opposed to the Mk1?s rope-type, plus, stronger 125E rods. The MkII engine also had sleeved tappet bores, better oil returns to the block, plus a 6-bolt flywheel fixing in the crank, which supersedes the earlier 4-bolt type.

In addition, you will also find a Twin Cam in Lotus Elans and later Europas. Naturally, there were several versions of these too. The Special Equipment (S/E) with 115bhp was fitted to S2-S4’s, whilst the Elan Sprint received bigger valves (and has Big Valve on the rocker cover), higher compression, better cams and exhaust, resulting in 126bhp.

There is also a Stromberg – carbed engine, although most had a Weber DCOE type manifold cast into the head, which interchanges with the similar and occasionally fitted, Dellorto side draught.

Twin Cams do have a reputation for water pump failure but this is mostly due to the engine being left standing for long periods – the pump goes dry and rips the seal when it is turned over. We have re-designed this area to incorporate a modular type water pump so that it’s easier to remove and replace. We also offer the water pump housing in two heights to suit standard or Crossflow based engines.

The latter is also a popular route for building a Twin Cam since L-blocks are becoming scarce. In addition, the Crossflow block can be increased up to 1700cc obviously giving a performance increase too. We also stock the special spacing components required, for this conversion.

More power is reasonably straightforward with the engine responding well to head porting, cam change and 45DCOEs. A usable 140+bhp can be achieved with the right cams. Due to the age of most head castings, we would recommend getting the head checked over first to advise on how suitable it is for further improvements to be made. We stock a whole range of replacement and performance parts for this engine including forged pistons, steel cranks / rods, steel flywheels, camshafts, large valves, steel tappets and much more besides.

Ford Kent Crossflow Tuning Guide

Ford Kent Crossflow Tuning Guide

This engine was introduced in the Ford Mk2 Cortina and differs from the earlier units by having the carb on the left and the exhaust on the right – hence, crossflow.

They also varied from Pre-X/Flows in that the combustion chamber was shifted from the head to the bowl of the piston and were know as BIP engines (Bowl In Piston). Early heads also feature a small combustion chamber in the head too.

Early blocks bore the casting marks 681F and capacities you’ll find are, 940, 1098, 1298 and 1599. You’ll find a X/Flow fitted to Mk1/2 Escorts, Mk2/3 Cortinas, Mk1/2 Capris plus late Transits. Most cars came with a single choke Ford IV carb although the 1.3 and 1.6 GT models had a 32/36 DGV Weber twin choke.

1970 saw the big change to the thicker-walled 711M block with square mains caps, large diameter followers, wider cam lobes and modified crank seal. Also, the head was now completely flat.

There are two main capacities of 711M, determined by block height – the 1600 is 7/16″ taller and you can see the difference between it and the 1300 by the space between the water pump and head. Also, the 1300 has 711M 6015 AA cast in the side whereas the 1600 ends in BA.

The engine was also fitted to 1.3 and 1.6 Mk1 Fiestas in the 80s with a 771M casting. These feature no side engine mounts plus a shortened water pump and timing chain/crank area.

The final versions, OHV, HCS and Endura are similar but shorter versions and share very few if any inter-changeable parts and reverted back to the original pre-X/flow design of a three bearing crank.

Kents are quite easy to tune to GT spec, which usually means the biggest capacity block, slightly bigger valves (usually taken care of with a performance head), GT cam/A1, free flow exhaust and twin choke Weber – you should see around 80-90bhp. Switch to a Kent BCF2 or a 224 and you’ll be approaching 110bhp. For all builds we would recommend ARP rod bolts and replacement of the front pulley for a one piece steel item. The valve train should be strengthened with steel posts, spacers and rocker shaft to cope with the additional stresses caused by high lift cams, HD valve springs and higher revs. A double timing chain kit should also be fitted for the same reasons. Performance heads are available in both iron and brand new aluminium and all can be ordered with unleaded seats.

You can use the old Cosworth A-series cam profiles too, which are long duration and lower lift. However the current Kent Cams, high lift and short duration type are friendlier on emissions with less lobe overlap resulting in reduced un-burnt fuel down the exhaust.

Add a stage 2 head and Kent 224 and you’ll be pushing 115bhp although the favourite X/Flow cam is the 234 for 118-120bhp. You should get this with a re-jetted twin choke although twin 40 DCOE Webers would be better. This is an all round great cam and engine spec for the road.

A 244 cam and stage 3 head results in 135-145bhp, although, these figures are best achieved with a recommended maximum 83.5mm bore and forged Accralite pistons, giving 1700cc. There is a cheaper option in that the compression can be raised using modified 1300 pistons in the 1600 engine, giving a ratio of around 10.3:1. Capacity is easily increased with cast pistons available up to +0.090″ oversize which will give 1696cc.

40 DCOEs tend to be on their maximum choke sizes at this stage so many switch to 45s. However this does result in lower gas speed and less low down torque, which is important on the road.

All side draughts need a side exit distributor cap (available for Lucas and Bosch distributors) to clear the inlet manifold and for convenience it’s best to fit an electronic ignition kit such as an Aldon Ignitor or Lumenition. For a complete ignition solution, our constant energy, non-vacuum modified Bosch distributor and coil kit is ideal for most modified engines.

This is about as far as you want to go on the road since you’ll be stretching the 7500-8000rpm limit of the crank. After this and you will ideally need steel components, which we have a superb range including cranks, rods, flywheels and forged pistons. To complement these we also have full-race spec heads to take the Kent as far as possible on the race track – currently that’s about 185bhp+.

Ford Essex V4 and V6

Ford Essex V4 and V6

This Ford engine can be viewed as a kind of scaled down American V8 and it certainly weighs as much! Originally introduced in 1965 in even more scaled down V4, the Essex was available with 1663 and 1996cc. 1966 saw two extra cylinders added, resulting in 2494 & 2994cc.

However, the engine most are concerned with is the Post-1970, uprated unit, which is very similar to the previous units BUT, there are plenty of parts that aren’t interchangeable. So, be careful and make sure you have the correct engine before you throw money at it.

The 3 litre Essex appears light on BHP at 138, especially compared to the engine that replaced it – the Cologne, which weighs in at 160bhp. But, the 3 litre’s biggest strength is bucket loads of low-down torque with tuning potential reaching almost 300bhp. At this level though, it gets a touch temperamental, so be warned! Before you really go mad, there are two areas you need to pay attention to – first, the engine runs on 4-Star so unleaded seats need fitting. All our heads can be supplied converted, which is a good excuse to upgrade to a pair of performance heads too. The second consideration is the fibre cam timing gear, which can easily shred with more power piled in. We stock a steel replacement cam gear and again a good plan is a steel gear upgrade plus cam swap at the same time.

For starters though, the 38 DGAS carb is capable of fuelling the engine to 180bhp with re-jetting plus an electric fuel pump. It is a touch thirsty being a double pump type rather than a vacuum secondary like the 40 DFI5 Weber replacement. You should get better economy with the latter but, no matter what stage you start, replace the restrictive airbox for a K&N filter.

So, a pair of Stage 1 heads should see an extra 8-10 bhp, Stage 2 another 6-8 but, combine the latter with a Kent V63 cam and you’ll see around 180bhp. Go to our biggest valve sized head, plus a Kent V66 cam and power will be close to 200bhp.

Alternatively, the Burton cams range will give you similar performance but in a different way – these tend to conform to the “old-school” low lift, long duration theory, which is perfect for historic track use but not brilliant when it comes to emissions control.

To obtain higher levels of engine power, you need to uprate the induction because the limit of the DGAS will have long been exhausted. Here it can get expensive although extremely good looking! We can supply a manifold to fit triple 40 DCNFs, which should power the engine to around 240bhp. More capacity is fairly common although the largest safe bore size is plus 0.060″. We stock Accralite forged pistons that allows up to 3161cc.

There are a few weak areas on this engine – the timing gear we have already addressed but, if you intend revving past 6500, it is advisable to have the crank cross-drilled for better lubrication.

However the rev limit is around 7500 with heavy duty rod bolts. The press-fit of the pin in the small end is also a problem area.

Balancing this engine can be tricky since it’s a V engine and any removal from the flywheel weight will mean a complete internal balance of components.

At the top of the engine, the pressed steel rocker arms pivot on a stud that is pushed into the cylinder head. Serious engine power needs these replacing with threaded inserts and stronger roller rockers fitted too.

Ford Duratec HE Tuning Guide

Ford Duratec HE Tuning Guide

This is the latest exciting power unit to come from Ford and looks very much like the Zetec – especially when that engines badged as such! But there are big differences – the engine has chain-driven cams as opposed to the Zetecs belt, plus the induction and exhausts are respectively on the opposite sides.

You will find this Mazda/Ford designed unit in Mondeos from 2001, plus the current new Focus and Fiesta ST150. Capacities are 1.8, 2 litre plus an American 2.3 litre version, which is available in this country too.

The engine features an alloy block and head plus some clever technology straight from the race track. The crank sits up inside the block and is held in place and braced at the same time, with an aluminium girdle. Oil drain galleries run down the side of the block directing the returning oil away from the crank thus not slowing it down.

The crank is strong but the rods and pistons arent necessarily so. They owe their appearance to proper race items but in truth, the ultra-slim skirted pistons are cast rather than forged. The rods are a touch boxy although theyre svelte. The combination though results in a free-revving assembly ideal for controlling emissions – it spins up quickly thus negating the need to use up fuel doing so.

Unlike the Zetec, the head has big ports and very large valves, again adding to its well-breathing/low emissions status.

What this means to us is it doesn’t take much to tune the Duratec to around 200bhp, at which point, you need to switch the rods and pistons to more reliable components. We already stock Forged Accralite pistons and H-section Farndon steel rods for such conversions.

To see increases from standard power however, it is necessary to perform an induction change, preferably to throttle bodies although a manifold is available for DCOE side-draughts. We list the Weber Alpha and Omex throttle body kits as well as Cosworth and Titan throttle body assemblies which should cover most requirements for induction.

The Duratec is currently a very popular choice in kit cars, where it completely transforms the car into a reliable road rocket with the best modern engine combination. In this format though, it needs turning round to rear-wheel drive. Like the components we offer for the Zetec, we also do a full range for this engine too, including re-directing water manifolds, sumps and bellhousings to adapt the engine to a Ford type RWD transmission – in standard form the unit does not comply to the classic Ford bolt pattern.

We can also supply complete Duratecs built by Cosworth on the same assembly line as their Formula 1 race engines. Which kind of speaks for itself in terms of quality! These are available in several levels of tune ranging from a 195bhp full engine to a 300bhp unit.

In addition, the Cosworth range encompasses plenty of parts to get the best from the engine in whatever car it’s fitted to – whether that’s the standard front wheel drive layout, as in the Focus, Fiesta or Mondeo, where a Cosworth d-Power Inlet manifold really makes the best from the standard type induction. Or, you can replace the lot with a roller barrel assembly, suitable for both front and rear wheel drive – it really does depend how much power you want, since there’s loads for the asking.

An enormous Cosworth range is now currently available for this engine, which practically guarantees the power output they quote. With the name to back it all up, you really can’t go wrong.

If you’re looking for a futuristic engine this is it!

Ford CVH

Ford CVH

Introduced in the front wheel drive Mk3 Escort in 1980, the Ford CVH has been available in both normally aspirated (N/A) and turbo forms and it?s been tuned to produce daft power using both methods.

Most common capacities you’ll find are 1117cc, 1296 and 1597. However, the 1300 was dropped in 1986 and replaced with a 1392 (1400). This was also a significant year since the oil pump system was revised for use in the Mk4 Escort. The only rear wheel drive version was available in the Sierra in 1800cc format. Sierra engines were based on US-spec 1905cc units and share few components with the smaller CVH engines. However, their thicker block was popular with 1900cc conversions, particularly RS Turbos.

Cars you’re likely to find a CVH fitted to are, Fiestas, Escorts and the aforementioned Sierra. Early Mk5 Escorts carried the engine but it was phased out in favour of the Zetec. Fords early range also included the very special RS1600i, which differs from regular cars since it has fuel injection, solid lifters, plenty of motorsport features and the highest N/A power, 115bhp.

CVH stands for ‘Compound Valve-angle Hemispherical’ and as such featured a “Hemi” type combustion chamber. But, there are differences because the later “Lean-Burn” series has a heart type chamber so you need to be sure which one you’ve got – the only sure way is to take it off because casting numbers can be misleading. Either head type can be tuned although the “Hemi” will generally give the most power. Your head will need inspecting since some feature oversize cam bearings and lifter bores.

The combination of a Burton Stage 1 head and a Kent CVH22, should release about 15bhp extra and you can use the best standard type carb from the XR3/early XR2 (Weber 32/34 DFT) in conjunction. These engines are very cam-timing sensitive and really do need a vernier pulley to see the best.

Stage 2 and a CVH 33 should see another 5-10bhp although you’re best now switching to twin choke Webers. Most common are DCOE side draughts – either 40s or 45s for more top-end power. However, these can cause space problems so the rarer DCNF down drafts are more suitable.

The bottom end is pretty strong although there is a rev limit of 6,000rpm but this is more to do with the lifters rather than the rods – better bolts ensure they are safe anyway. We would recommend solid lifters beyond the limit of 6,500rpm, which is when you really need to consider forged pistons too. Standard Mahle pistons will go to 10.2:1 by skimming the head although this needs to be checked to avoid valve contact. Accralites are recommended beyond this level although these are to special order only.

At this stage we’d also recommend our Farndon H-section rods and if you’re really serious a steel crank as well – however there are plenty of CVH engines racing with the standard cast crank.

Turbo engines are reasonably simple to tune to around 180bhp, which is normally achieved with a Bayjoo chip, -31 actuator, air filter and stainless exhaust. These modifications will allow around 1BAR of boost. Beyond this and you’ll need a larger intercooler to drop charge temperatures plus a hybrid turbo to hit 200bhp.

You’ll get a touch over this with a Kent CVH34 cam as well as reaching the limit on the standard pistons, for which we stock Accralites to better handle boost pressures. These come with finished crowns and a CR of 8.0:1 but can be machined for lower compression ratio.

We also stock all you need to perform the ZVH bottom end conversion, which will give you a 2.0 litre Zetec bottom end and the potential to go beyond for true monster power.

Engine – General – Burton Power

Whether you drive a modern or older car, Ford or non-Ford, it is possible to improve engine power and efficiency by fitting selected performance products which simply bolt on to the engine externals.

High flow air filters allow the engine to breathe better which, coupled with adjustments to the carburation or injection, will provide an improvement in power and response. Most factory fitted ignition leads are carbon cored and these will deteriorate with age. Fitting a high specification lead set will restore engine performance (especially under heavy engine load conditions), and will also improve cold start operation. While on the subject of ignition, if your car is an older model, fitting an electronic ignition kit will ensure peak performance for all conditions – and there are no points to worry about. Engine driven cooling fans are renown for causing all sorts of problems. In the summer, in traffic, they allow the engine to overheat – in the winter they prevent the engine warming up properly – and driving those fan blades around absorbs a lot of useful engine power. The answer, of course, is to fit a thermo-statically controlled electric cooling fan.

The value of any improvement or performance upgrade will be determined by the “health” or otherwise of the engine in question. The areas of improvement mentioned thus far are fairly modest but to venture much further along the road to high performance will be doomed to failure if your engine is not in a sound condition. Some bolt-on products such as carburettor conversions or engine management (chip) upgrades will increase the stress placed on an engine and can exacerbate any existing wear problems, so it is always a good idea to have the engine fully checked over and serviced beforehand. At the very least make sure the engine is treated to an oil and filter change using synthetic or premium quality oil. Last, and probably one of the most popular bolt-on performance enhancing items to be purchased, is the exhaust system. Many original equipment exhausts are restrictive in their design and the full potential of any increase in engine power will not be achieved until the exhaust is replaced with a suitable free flow system. A very comprehensive range of manifolds and systems are available for most cars including the increasingly popular stainless steel types.

So let us now move on to the more serious aspect of engine modification. The next logical step is to modify the top end where, in most cases, substantial power gains can be achieved. Choosing the correct stage of cylinder head and matching this with the right camshaft is very important, and at Burtons we are always on hand to advise our customers on the best combination for their specific usage. Most modern engines are overhead cam (OHC) design and removing the head and cam can be carried out with the engine ‘in-situ’. For older overhead valve (OHV) pushrod engines, a cam change will almost certainly require the engine to be removed from the chassis and at least a partial strip down of the bottom end.

Finally, any attention or modification to the bottom end will require a complete engine strip down. If the cylinders are to be rebored then an increase in engine capacity is always worth considering. Whilst on this subject, it should be recognised that one of the easiest routes to more power is to fit a larger capacity engine. Many cars have various engine options for any given model so moving up from a 1300cc to a 1600cc engine or a 1600cc to a 2 litre should give a very noticeable increase in performance. This type of work should be carried out by a professional engine builder but for the competent enthusiasts amongst you, we offer the following additional advice:


General Advice

Firstly, what follows is not intended as a complete guide to performance engine preparation. It should be regarded only as a supplement to manufacturers workshop manuals and specialist publications on engine tuning and related subjects.

First decide on your objective – this might sound obvious but we’ve been in the business long enough to realise that many projects are carried out without any real planning. Decisions should be made regarding usage (will it be an everyday road car, occasional use / second road car, or one of the many classes of off road competition cars), cost (unless money is no object you should decide on a realistic budget that you can cover), and what facilities are available to you to carry out the work. This last point is extremely important because, apart from a good selection of tools and equipment to hand, a successful engine rebuild can only be guaranteed if the work is carried out in controlled, dare we say “clinical” conditions.
Taking these points one by one: Usage: If the car is to be used on a daily basis then flexibility and smoothness will be as important an issue as extra power. A moderate increase in power over the standard engine can always be gained (albeit at a slight rise in fuel consumption) whilst still retaining the original driveability. However, the products to be used in such conversions should always be carefully selected with careful consideration to other factors such as:

  • AUTOMATIC TRANSMISSION: As a general rule be very wary if you are considering any head or cam modifications. Such modifications can drastically alter the operation of an automatic box due to the changes in manifold pressure/vacuum. The ability of many auto boxes to cope with the increased power must also be questioned.
  • EMISSIONS: Current legislation dictates strict controls over exhaust emissions. Over enthusiastic tuning may result in an MOT failure if unsuitable camshafts, carburettors, etc., are fitted.
  • FUEL INJECTION (MFi): The early mechanical types of fuel injection systems do have a small range of adjustment. Professional recalibration of the injection system will be required for any large increases in performance.
  • CFi/EFi & ENGINE MANAGEMENT SYSTEMS: As used to control all modern car engines. Some early pre 1992 EFi types (e.g. Mk4 Escort CVH) did have a provision for adjustment of the TPS but adjustment should not be attempted by the inexperienced. For all other types professional ‘re-mapping’ may be required depending on level of tune.
  • CATALYTIC EXHAUSTS: These are now common place in all modern cars and are very sensitive to changes in exhaust emissions.

For occasional use cars (usually a second vehicle) the above criteria apply but, since power gains are more important than some loss in low speed torque and flexibility, the stage of tune will generally be higher. Off road competition cars allow the most scope for the ultimate stage of tune but will, invariably, have certain restrictions depending on regulations/homologations.

Cost:  If you can’t afford to do the job properly please think again. The worse thing anyone can do is shop around for the cheapest parts. That is not to say you shouldn’t find a cost-effective supplier to deal with. The lesson we are trying to get across here is that not all components on sale are of sufficient quality for use in a standard engine let alone a highly tuned one! Saving a few pounds on a cheaper head gasket will not seem such a good idea when the head has to come off again after only a few weeks use. For other performance critical parts the cost of failure can be far greater.

Facilities: You will need a clean, light garage or workshop together with a comprehensive tool kit which will also include the following specialist tools:

  • Good quality torque wrench.
  • Valve spring compressor.
  • Piston ring compressor.
  • Feeler gauges.
  • A pair of heel bars and/or a puller.

If you intend to set up cam timing you will also require a DTI gauge and magnetic stand together with a 360° protractor. A good workshop manual should also be to hand.
Engines can be built on a flat bench but the job is far easier when using a proper engine stand. These are relatively cheap to buy (see our tool section) or can be hired. As mentioned previously, cleanliness and degreasing the components is essential, as is a good supply of lint free cleaning cloth. Use compressed air (if available) and/or gallery brushes to clear oil galleries, etc., and assist in the removal of any residual dirt or debris. (Note: always wear goggles and gloves and keep nozzles pointing away from body.)


Engine Preparations

This is a general guide to correct procedures and will apply, wholly or partly to all types of engine rebuild. However, before the engine rebuild can begin the engine needs to be stripped down, cleaned and examined, a procedure which many undertake with undue haste. During the strip down the following should be observed:

  1. Wait for the engine to cool properly before removing the cylinder head – this applies especially to aluminium types. The consequence of not waiting can result in a warped head.
  2. Mark the location (and, where applicable, orientation) of all major components especially valves, tappets, camshafts, pistons and rods, shell bearings by placing in clearly marked containers or racks.
  3. Before removing bearing caps (e.g. camshaft, con rod, main bearing), make sure they are clearly marked for position and orientation N.B. they must go back in the same position or on the same con rod and the right way round.

Once stripped all parts should be thoroughly cleaned and inspected with specific attention to any areas of bad wear or damage e.g.:

  1. Blown head gasket / burnt out valves – cylinder heads should always be thoroughly examined for cracks or distortion. Simply fitting a new gasket or valve is not the answer.
  2. Damaged piston/rings – always check the cylinders for wear and damage. If the pistons need replacing, a rebore is almost certainly needed as well.
  3. Badly worn crankshaft shell bearings – if the crankshaft is badly scored it must be reground to the next undersize. However, just as important are the con rod and main bearing housings that the shell bearings fit into. These are often overlooked and any wear or distortion in these areas will cause premature engine failure.

Cleaning should include the removal of all oil gallery plugs to enable thorough cleansing with special brushes (see tool section). Many parts can be re-used during the rebuild but the following items should always be replaced:

  • All gaskets and seals.
  • Timing belts or chains.
  • Timing belt / chain tensioners.
  • All major fastenings including cylinder head, con rod and flywheel bolts.
  • Shell bearings.
  • Piston rings.
  • Oil Pump drives.

We will now discuss what modifications can be carried out to increase engine performance and some of the pitfalls to watch out for. We shall assume that any remedial work to restore these components to their original specification has been carried out.

Cylinder Heads: Arguably the most complex and important engine component especially when it comes to modification work. If a road stage cam kit is being fitted it will usually involve fitting the heavy duty valve springs. Always refer to the manufacturers fitting guide and check the valve spring fitted length – the valve spring seats in the cylinder head should be machined if there is not enough clearance. New tappets/followers must always be fitted when installing a new camshaft. If you have an older engine which is not suitable for running on unleaded fuel, now is a good time to consider having hardened exhaust valve seats fitted. Any higher stages of tune will usually involve fettling around the ports and chambers to accommodate larger valves and the fitment of specialist high performance parts e.g. 214N valves, bronze valve guides, heavy duty valve springs, etc. This type of work is best left to the experts and Burton Power can offer our customers a full range of cylinder head modification services including unleaded conversions. Finally, a check on the matching of the inlet and exhaust manifold to the cylinder head ports should be carried out. The exhaust manifold ports should always be LARGER than the cylinder head ports to prevent the build up of any turbulence or back pressure. The inlet manifold ports should be slightly smaller than the cylinder head ports or, preferably, matched and dowelled by a specialist.
Finally, remember to check that the manifold gaskets do not mask any areas around the cylinder head ports. Large bore gaskets are available for the popular engine types


Bottom End

The two most important criteria for this area of engine tuning are strength and weight. For the more moderate stages of tune most of the standard parts can be used.


Cylinder Block

Most standard blocks are strong enough to withstand at least a 50% increase in power or more. Problems usually arise because machining has compromised their structural strength. The two main areas for this are the cylinder bores and the top face. Excessive machining of either of these will result in piston ring blow-by and/or head sealing problems.
As a general rule most cylinder blocks will overbore safely to +1mm (.040″) and many are OK up to +2mm (.080″) – this will give a very useable increase in capacity and power. Exceeding these limits however will greatly increase the risk of cylinder bore distortion and piston ring blow-by. “Decking” the top face to improve compression ratio and combustion (squish) usually involves machining no more than .5 to 1mm from the block face and this should have no detrimental effect. However if the block face thickness is reduced to excess this may cause irreversible gasket sealing problems. It should also be noted that excessive machining of the cylinder head and/or block face on OHC type engines might result in inadequate tensioning of the timing belt or chain. For some full race applications the main bearing caps will need replacing for stronger steel items. These cannot be supplied as direct replacement parts and will require in-line boring to the cylinder block.


Crankshaft and Con Rods

These will be OK for most stages of tune provided they are structurally sound.
Crack testing is advisable for any serious tuning especially if the components are second-hand and of an unknown source. Apart from conforming to original equipment tolerances they should be free from any marks or blemishes that could cause stress raisers which, in turn could propagate into a crack at some later stage. Pay particular attention to the fillet radii on the crankshaft journals and have these polished and rolled if necessary. Check the outside faces of the con rod beams and polish out any flaws. The con rod cap should also be inspected around the fixing points – these areas should also be smoothed and radiused. Certain types of crankshafts and rods can have additional heat or surface treatment to enhance their durability. Nitro-carburising of some crankshafts and shot peening con rods can be beneficial if carried out under strictly controlled conditions. Wherever possible fit heavy duty shell bearings – preferably lead indium or lead copper if available.



With the exception of turbo-charged engines most production engines are fitted with cast alloy pistons which are quite adequate for most of the moderate stages of tune. The problem arises when compression ratios are raised to a point where detonation becomes unavoidable and forged pistons must be fitted. Since many other factors are involved, this critical ratio is not the same for every engine. Assuming the fuelling and ignition are set correctly, then 10.5:1 is generally acknowledged as the very maximum for a good quality cast piston, and even then, you must accept a substantial reduction in its service life. Due to the complex shape of the pistons and their very fine machined tolerances, any additional machining should be carried out by a specialist. Pistons should always be replaced in matched sets but if you are replacing only one or two then do make sure they are match balanced before assembly.



Apart from being a handy place to fit a clutch and starter ring gear, the flywheel’s primary function is to smooth out the transmission of power from the crankshaft and for this you require mass (weight). The problem here is that this weight acts as a resistance to, as well as a store for, the energy produced by the engine. Lightening the flywheel will improve the engine?s response to throttle openings but not the actual power output. Unless the flywheel is abnormally heavy we do not recommend flywheel lightening for road stages of tune. The slight loss of low speed torque and flexibility resulting from the tuning modifications carried out, can be greatly exacerbated by a lightweight flywheel. However, for all serious tuning a lightweight flywheel is essential. Standard cast iron flywheels can be lightened but there is always a risk of them exploding if too much material is removed from critical areas. The rule here is not to be over-ambitious when machining weight from a standard flywheel – it isn’t worth the risk! The safe answer is to buy a steel flywheel which are available for most popular engine / clutch formats. The final point on flywheels is to make sure it is firmly secured to the crankshaft. Always fit new HT bolts and always double check that they have been torqued correctly. If engine speeds in excess of 7500rpm are anticipated then, wherever possible, the flywheel and crankshaft should also be double dowelled for extra security.



Original equipment clutches should cope with moderate power increases (15-20%) but if the standard clutch needs replacing then it would make sense to fit an uprated item. For road car conversions it should be noted that clutch pedal pressures will increase when fitting a stronger clutch. For competition applications a wide range of single, twin and triple plate clutches are available together with the special flywheels required to mount them.
Once all these components have been sorted they should be balanced. This will provide for a smoother more reliable engine, especially at high revs, by eliminating any vibration caused by unequal balance. We can provide a full balancing service for all engine types, including Vs.


Lubrication Systems

All production engines employ a wet sump system where the oil lies in a reservoir or sump below the crankshaft. This system works fine for most applications but the following points should be observed. High pressure pumps (typically 25-30% higher than standard) will ensure an adequate supply of oil to the engine, especially during heavy load condition.
High capacity pumps (which are also high pressure) are designed to cope with the higher flow demands of engines fitted with ancillary equipment such as oil coolers. For mild stages of tune the standard pump is quite adequate providing it is functioning efficiently. One of the most important areas to watch is the condition of the oil pump drive gear or shaft (sometimes referred to as the quill). These components (especially the quills) should always be replaced with an original equipment new part.


Engine Rebuild

The following bullet points highlight important procedures during the re-assembly of a modified engine:

  1. THOROUGHLY clean and check ALL parts – your engine’s worst enemy is dirt, and even new parts may need cleaning. This includes the head and block and all oil galleries.
  2. ALWAYS fit new high quality gaskets and seals and ensure all shafts and mating surfaces are free from burrs and defects. Use correct sealants or lubricants where necessary.
  3. LIBERALLY oil all internal parts during assembly. Use the special assembly lube or gear oil on cam lobes and tappet faces.
  4. ALWAYS replace cam followers when fitting a new camshaft.
  5. ALWAYS replace con rod, flywheel and cylinder head stretch bolts. All other fastenings should be checked for wear or damage and replaced as necessary. For high spec. engines, race quality fastenings are available for most applications.
  6. CLEAN all threads and fastenings prior to fitment and use a good quality torque wrench on all critical components. Apply an anti-seize lubricant to all cylinder head fixings.
  7. IF you are fitting high lift cams, special pistons, or large valve heads, always carry out a dummy engine build and check valve to piston/block clearances. Machine piston crowns/valve pockets or block face as necessary.
  8. INCORRECT cam timing can severely reduce the power output so do not overlook this important area during assembly. Use adjustable cam pulleys or sprockets where available.
  9. CHOOSE compatible parts for your specific conversion. A full race spec. head will be next to useless if fitted to a mild road stage engine. Modified camshafts and cylinder heads in particular should be chosen with care.
  10. UNLESS you know what you are doing, avoid over-lightening components. Reducing the weight of some parts may also reduce their strength to a critical level.
  11. ALWAYS have the engine assembly balanced – it will make a lot of difference to the smoothness and help maintain optimum reliability.
  12. DON’T forget the clutch – depending on the power increase, a suitable heavy duty or competition clutch assembly will be required.
  13. OIL and FILTER – the importance of using the correct specification of oil cannot be overstated.

Most engine modifications should be followed up with a professional engine tune. Apart from emissions, the correct ignition timing and fuelling is paramount if you want the best return for all the expense and effort you have put in. Get these important settings wrong and you may loose more than just a bit of power. Over-fuelling (rich mixture) can result in excessive piston, ring and bore wear. Under fuelling (weak mixture) or retarded ignition can cause overheating problems. An ignition set with too much advance is likely to induce detonation or “pinking” which, if left uncorrected, can shatter pistons and place excessive loads on the bottom end. You have been warned!
Lastly, please check that your suspension and braking systems are adequate for the power increase you have achieved.

Camshaft Fitting & Timing

Camshaft Fitting – Burton Power

Due to the high number of phone calls we receive concerning the fitment and timing of camshafts, we have decided to include camshaft fitting instructions on this website. The first section describes what to look out for when fitting a camshaft to avoid premature failure. The second section describes a typical method for timing a performance camshaft.

Camshaft Fitting Instructions

Burtons do not recommend installing a performance camshaft in a vehicle fitted with an automatic gearbox. The installation and first few moments of running are critical factors in the life of the camshaft. Failure to install the camshaft correctly will have a drastic effect on the life of the camshaft and in the worst cases can result in immediate failure. The following instructions must be adhered to in order to obtain maximum performance from the engine and to ensure a long and trouble free life from both camshaft and associated components. These instructions are also provided in addition to the original manufacturers installation procedure. Where a camshaft is being replaced due to excessive wear, it would be highly recommended to strip the engine and fully clean the internals.

Metal particles present in the sump, oil pump, bearings and oil galleries will soon play havoc with the new cam. It would also be wise to check the oil feed system. Low oil pressure due to a worn pump, blocked pick-up pipe or blocked oil galleries will quickly wear the new cam to the same state as the one being replaced. In other words, before replacing a failed camshaft, make sure you find out the reasons for the failure and correct it! Before fitting the camshaft, check that it is identical in every aspect (with the exception of the lobe profiles) to the one being replaced. Special attention should be given to the oil feed positions and journal diameters as variations may occur during the manufacture of the engine. Also check that any gallery bungs present on the old cam are also in place on the new cam. Do not remove the black phosphate coating from the new cam lobes. Liberally coat both the camshaft and cam followers with a proprietary cam lube or engine assembly compound.

At Burtons, we recommend and use Graphogen, a colloidal graphite paste. Failure to do this can cause scuffing between the surfaces of the cam and followers, which will result in premature wear. Ensure that followers are free to rotate in their bores where applicable. It is essential that new followers are always fitted, regardless of the condition or limited use of the old followers. Failure to do so may cause premature components failure and consequently will invalidate any warranty claim. Upon installation, the valve springs must be checked to ensure that:

i) the fitted length (installed height) of the valve springs match the figure provided by the manufacturer (see fig. 1). If too small, then the valve seat areas in the head will require machining. If too large, shims can be added to the spring seat. Due to varying manufacturing tolerances of cylinder heads, all springs should be checked and measured for clearance.

ii) coil binding does not exist at full valve lift. This is the condition where the spring is fully compressed (see fig. 2). As a guide, at full cam lift the spring should be able to compress a further 0.060″ (1.5mm) before the coil bound condition is reached. This can be checked by inserting feeler gauges between each coil of the spring and adding the results together to get a total clearance figure. Due to varying manufacturing tolerances of cylinder heads, all springs should be checked and measured for clearance.

Check the clearance between the bottom face of each retainer and the top of the guide or stem seal at full lift (see fig. 2).

This should be a minimum of 0.080″ (2mm). If this clearance cannot be achieved, the top of the guides must be machined. When double valve springs are being installed in place of singles, ensure that the inner spring is correctly located and the correct retainers and platforms are used where applicable.

When modifying engines that utilise finger followers i.e. SOHC Pinto, it is imperative that you ensure the followers remain in the original attitude relative to the cylinder head. Failure to do so will alter the rocker geometry, increasing or decreasing valve lift and can result in failure of both cam and followers or excessive valve stem/guide wear.

For OHV engines, attention should be paid to rocker arm geometry for the same reasons.

Camshaft Timing

Determining True Crank TDC Position: Head off Block

Although the crank pulley will have a mark to show TDC position, this point may not be accurate due to manufacturing tolerances. It is always recommended to calculate the actual position of TDC rather than rely on the mark on the crank pulley. Fit the timing disc to the front of the crankshaft. A pointer for the timing disc can be made from a piece of bent wire secured under a suitable front cover bolt. Position a dial gauge to measure the travel of No 1 piston (see right). Turn the crank until the piston is at its maximum height and zero the gauge. You will find that there is a dwell period of approx. 10 degrees where the piston is at its maximum height. True TDC position is at the centre of this dwell period. To accurately measure the position of TDC, rotate the crankshaft and stop at a figure just before TDC, for example 0.020″ on the dial gauge. Record the figure on the timing disc from the pointer. Now rotate the crankshaft and stop at the same figure (0.020″) after TDC. Record the figure on the timing disc again. True TDC is positioned in the middle of these two figures. The TDC position can be calculated by adding the two figures together and dividing by two. Adjust the timing disc so that it reads zero on the pointer at true TDC.

Determining True Crank TDC Position: Head on Block

If the head has not been removed when changing the cam, it is still possible to measure the true TDC position. The procedure is the same as before but the movement of the piston is recorded by using an extension resting on the piston crown (such as a socket extension or our special tool on page 114). Access to the piston crown is made through the spark plug hole.

Timing in the Camshaft

Rotate the crankshaft clockwise to 90 degrees after TDC. This will make sure all the pistons are half way down the bore. Now position the dial gauge so that it can read the lift of the inlet valve of number 1 cylinder from the top of the valve retainer (see left). Rotate the cam until the gauge shows that the valve is at full lift. As with the crankshaft, there will be a dwell period where the valve is at full lift. True full lift is at the centre of this dwell period. Roughly position the cam at true lift position. Now rotate the crankshaft clockwise to the full valve lift position (as specified on the camshaft data sheet – this figure is typically from 100 to 120 degrees after TDC), fit the timing belt or chain and set up the tensioner.

Now rotate the crank clockwise until the inlet valve of number one cylinder is just off full lift position (such as 0.005″ or 0.15mm). Record the figure on the timing disc from the pointer. Then continue to rotate the crank clockwise until the valve has fully opened and then closed by the same distance as previously used (0.005″ or 0.15mm). Read the figure on the timing disc again. The position of full lift is the middle of these two figures. The full lift position can be calculated by adding the two figures together and dividing by two. Adjustments can then be made to the camshaft timing, using an adjustable cam pulley or offset dowels, if this figure does not agree with the one on the data sheet. Check the timing again after adjustments using the same procedure. Having timed the camshaft, check that there is no piston to valve contact. Minimum clearance is 0.060″ (1.5mm). This can only be checked by dummy building the engine with a piece of Plasticine placed on the crown of the piston. As the engine is turned, the valves will indent the Plasticine. The clearance is then measured as the thickness of the Plasticine between the piston crown to the bottom of the valve indent. Before starting the engine, turn the engine over by hand to ensure that it turns freely. Prime the oil system and check that everything is set to ensure that the engine starts straight away. The engine must not be turned over for any length of time on the starter. Once started, do not allow the engine to idle for the first 20 minutes and keep the revs to a minimum of 2500 rpm. This will ensure adequate lubrication of the cam and followers and reduce the contact force between the cam and follower. If any adjustments need to be made within the first 20 minutes, then shut the engine down. Do not allow the engine to idle. Please note that new hydraulic lifters may in some cases operate with excessive noise for a few minutes before they are fully charged with oil.