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How-To Section: Tuning Small Ford Engines (Circa 1977)


The Ford range of engines exceeds even the Leyland one for availability of likely power producing units. Like the Leyland A Series, you can work on the assumption that given little or more effort all the four cylinder units are inter-changeable, even down to the later single overhead cam engines first used in the Mk Ill Cortina but usually known as the Pinto' engine because it was originally designed for the US Ford of that name.

Pre Cross Flow

997-1340: It's fairly easy to group the engines by design and tuning methods. The 997, 1198 and 1340cc units all belong to the first family, having three bearing cranks and like all the pushrod engines a bore of 80.97mm. You can in fact turn a 997 block into an 1198 or 1340 by simply fitting the appropriate crankshaft and connecting rods but while the 1200 conversion is well worthwhile steering clear of the 1340's, the crankshaft used at this capacity is hollow and is most definitely the weakest of them all. Don't use a 1340 over 10 to 1 compression ratio or 6000 rpm, although the others will stand a lot more. Heads are also interchangeable with effect a 997 head on a 1200 will raise the CR to about 10 to 1 and 85 mm bore Hepolite pistons in a 997 block will give 1098cc and in the 1200, 1320cc which is better than using the 1340cc engine.

All these engines can be tuned in the same basic way. The 28/36 DCD Weber twin choke, down draught, carb used on the 1500GT engine works well along with a modified cylinder head and a GT camshaft which is a simple and cheap mod. In fact, the GT camshaft alone will probably make more difference to the engine than the other, complementary, modifications. However, to fit a cam you have to remove the engine from the car and turn the block upside down to allow the mushroom shaped cam followers to drop clear of the cam lobes. A decent four branch exhaust manifold from a specialist such as Janspeed is also a good idea.

Once you've gone beyond this stage (and at this point ignore the 1340cc unit) you are faced with the need to improve the head further (Stage 111 say) with the addition of dual 40 DCOE sidedraught Webers. At this stage the power and rpm will have risen to a point where a complete engine strip and preparation job (lightening, balancing, etc) is necessary. The Ford oil pump needs uprating fairly early on and the non-synchro first gear gearbox on the 997 and 1340 engine is getting near the limit. However, with anything near 80 bhp from the smaller Ford engines you are reaching the point where you might as well consider swapping the power unit and gearbox for one of the larger engines in the range.

1300-1500 non crossflow: These units are five bearing crankshaft developments of the three earlier engines and can follow exactly the same tuning sequence as above, with the addition that the 1300 and 1500 can easily be converted to 15OOGT specification by bolting on the carb, exhaust manifold and camshaft from this engine. Then it's a modified head and twin Webers along with a suitable higher tune cam. If the GT carb is used in the non GT engines then the GT distributor must also be used. The 1300 and the two 1500 non cross flow engines all use inlet valves of 1.43 in diameter compared with the 1.27 in valves of the 997 to 1 340 cc units and these larger valves can be fitted to the smaller capacity heads with good effect as long as the rest of the head is gas flowed and the carburation and cam is also changed.

The 15OOGT uses the larger valves but in fact has a slightly smaller diameter valve throat than the other engines to speed gas flow.

The tubular exhaust manifold fitted to the 15OOGT is an improvement over the cast iron type but if you are making the swap anyway you can gain more power by going to a specialist product rather than the Ford one.

Beyond the GT stage of tune the 1500 (and 1300) needs twin Webers, a hotter cam such as the old Cosworth A2 profile which is offered by some tuners and a modified version of the Ford Twin Cam distributor which has no vacuum advance mechanism. A capacity increase (just as long as you're not trying to remain within a capacity class for some branch of motor sport) will take the unit to 1650cc with the aid of 85 mm pistons. This bore is about the limit for the 1500 block and, ideally, liners should be fitted to prevent the cylinder walls going porous and the coolant leaking through. With A2 cam, dual Webers, well modified head, good exhaust and 1650 cc the 1500 base unit is capable of around 125 bhp. But, again, you've got to consider that a swap to an even larger four cylinder Ford unit would be simpler, more reliable and (possibly) cheaper in the long run.

Cross flow:

There are basically two complete ranges of 1100, 1300, 13OOGT, 1600 and 16OOGT cross flow Ford engines. Those made between 1967 and Oct 1970 have varied head/ combustion chamber arrangement like this: 1098/1298 - completely flat head, combustion chamber in piston crown. 1298GT/1600/1600 GT-valves recessed into head, main combustion chamber in piston crown.

The later model ('uprated') cross flow units all use a completely flat head design and in fact have larger diameter inlet valves on all except the 13OOGT version which, along with better porting, means the later type cylinder heads are most definitely superior to the earlier ones. If you are planning in increasing power output of a pre1970 cross flow unit appreciably you are well advised to get hold of a later head. It's not good enough just to fit the larger inlet valves as the porting changes are important and, anyway, the valves are of a different length which will mean careful undercutting of the spring seats on earlier heads if they are to fit. The early cross flow units used camshafts similar to the previous Ford fours but the uprated engines have different profile cams except for the 16OOGT which retains the shaft originally used in the 1500GT and still and good first stage for almost all the other engines.

The five bearing, cross flow, units are good engines that will stand a lot of power (up to 150 bhp is possible) but there are two weak points earlier engines have mains bearing caps that are not as strong as later ones and the pistons, with their combustion chamber in the crown, are not too strong. The better, later, bearing caps are easily recognised by their square design while Hepolite do a forged cross flow piston that is much stronger but unfor- tunately fairly heavy and therefore tends to restrict the possible rpm of a fully modified unit.

Obviously, once again, non GT engines can be easily brought to GT speci- fication although the good old 28/36 Weber is replaced by another design that is not so easy to alter to accept different engine specifications and from then on it's the usual twin Weber sidedraughts, modified head (which does make a difference despite the fact there is no combustion chamber there), road/rally cam and exhaust system. Both 40 DCOE and 45 DCOE Webers can be used on this engine according to the stage of tune required. The standard GT downdraught Weber (DFE or DFM) tends to need replacing earlier than the 28/36 does on the 15OOGT because it is not so adaptable to jet and choke (they are cast - in and not removable) changes. Again, like the other units, the Twin Cam distributor needs to be used just as soon as the engine goes beyond a GT specification camshaft and an uprated oil pump is also a priority once there is likelihood of rpm rising considerably. Again, you can get a worthwhile power (and torque) improvement from boring the 1600 to 85 mm (Hepolite Powermax pis- tons again) and in this case the end result is 1760cc. A nice, tractable road and weekend rally engine for, say an Escort is a 1760 cc bore, twin 4ODCOE Webers, modified cylinder head and Ford's own BCF2 camshaft. This gives around l2Sbhp without any stress and is ultra-reliable as well as being fairly effortless.

With larger (45 DCOE)carbs and a fully modified head and cam the 1600(1760) unit can be taken to about 150 bhp but, yet again, there is little point going to this figure because the Twin Cam and BDA units are fairly easy fittings and have much greater potential.

Single overhead cam units:

Two engines but using a common block and crankshaft with just variations in bore and connecting rod length to achieve the 1.6 or two litre sizes. The cam- shafts are identical and the cylinder heads interchangeable but the 1.6 version (with a '6' stamped on it) has a smaller capacity combustion chamber. The 1.6 litre engine is of course used in the latest Escort Mexico as well as more mundane Cortinas and Capris while the two litre's most exciting home is in the RS 2000. Unless you want to stay at 1600 for a class reason you might as well consider swapping engines or increasing the smaller engine capacity to that of the larger if large power outputs are intended. In any case the tuning sequence is the same.

The engines are quite strong units with good crank and pistons (the combustion chamber is not in the piston) and the weak point is in fact in the cam and valve gear. High wear and possible breakage can occur at sustained high rpm. The only real answer is very careful assembly on high output engines that are likely to be used for competition. An oil cooler is a good idea for high output engines as is an uprated oil pump - although it is not as easy a job to change this as with other Ford units because the pump is in the sump rather than on the side of the block The carburation and exhaust manifold are the first things to change for more power. A good Stage One conversion is to fit the dual choke downdraught carb used on the V6 three litre engine with appropriate jetting this gives an appreciable improvement. Weber themselves have a carb fitting kit for this installation.

Then comes a decent four branch exhaust manifold and system and after that the cylinder head needs to be modified although the two litre seems to work well with twin 4ODCOE Webers, exhaust manifold and standard head and cam. For the reasons mentioned above a cam should be last on the shopping list.

The ultimate conversion for the single overhead cam unit must be Ford's own Group One kit which is available under a number of Rallye Sport part numbers. This comprises a modified head (with raised CR and bigger inlet valves), twin, dual choke, downdraught Weber carbs, high lift camshaft and free flow exhaust manifold. With this fitted the two litre engine gives just over 150bhp if it is all put together properly.

Vee engines:

The V4 units are not really a good basis for any sort of performance modifications. They are not particularly strong and very few specialist parts available. The smaller capacity unit can be brought up to 1996cc by using the crankshaft and connecting rods from the larger unit while the first aim for any lesser engine must be to bring it up to 2000E specification. The 2000E has an improved camshaft, dual choke Weber and a certain amount of alteration to the cylinder heads to give it the greater power output. A Minnow Fish carburettor seems to work well as a next stage on this engine and Piper are one of the few people to offer a hotter camshaft. Around 130bhp should be the maximum for this engine.

The V6 units, or more particularly the 3.0 litre engine, will on the other hand take a lot more power. Several tuning concerns have modified heads, camshafts and exhaust for the unit. Not far off 2OObhp is possible with a lot of work but a nice road modification is a simple carburettor change (Ford's own Group One spec Weber or a Minnow Fish) along with some extractor exhaust piping. Like the RS 2000 Ford have developed the engine quite consid- erably for competition and have a list of parts available through Rallye Sport dealers which include pistons, stronger connecting rods, oversize valves etc. The best engine to work on is the 3.1 litre RS 3100 engine that was produced in late 1973/74 and went into a limited production run on the last of the Mk 1 Capri models.





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