*INFO* 1.2 8v Tuning Guide

[Ste L]

Before commencing any engine modifications, it is advisable to ensure that all of the basic components are working well. This will save time and money. The engine itself should be in sound condition with no unusual knocking noises and no smoke. Theres no point spending money on an engine that is going to fail. Also check that the ignition system is in good working order. If in doubt use new plugs, leads and distributor cap, nothing fancy, as long as they work, there fine.

This guide is based at getting power on a strict budget. Even this will cost money, so if your only driving this particular car for a short while until you can afford something faster, dont bother, save your money. If however you see it as a project to get a quick little engine car and have fun, then these tips should be helpful. The only way you can really save money on any modification, is to do it yourself. If you are paying someone else, then change your pay details so that the money goes direct to the garage!

One last thing, if you have limited power, dont fit big body kits and wheels, I guarantee they will slow you down. I lied, another note, lose weight, drop the huge stereo system, and if you can bear it, strip some interior, it will make more difference than spending ?500!

Ok, on to tuning the 1.2:

You need to start hunting around the scrap yards.

Exhaust
You need to get a system from a GTE/GSI ideally. The SR models will still be an improvement, although I believe diameter will be bigger on the 1.6`s. Get the manifold, down pipes, and full system. The design is better with the twin down pipes, and this will flow the gasses out quicker. You will probably have to shell out around ?50 for the lot, but it will be far better than buying a performance back box.

Head
Stick with the one you have. It flows well, and will start costing to much money to play around with. If you really want to help, match the manifolds to the head by cutting the gaskets to the size of the manifolds and then taking metal out of the head to match the gasket. Personally for a beginner Id say not to bother. Its quite involved and you could do more damage than good. Cost ?0

Camshaft
Once gain the GTE/GSI is the best source. The camshafts are interchangeable, so the SR one will fit too. This will give increased duration and lift, but beware, try to use the followers that are with the new cam, and in the correct place. Also look at the amount of wear. There is no point picking a cam coz it is suppose to have 2mm higher lift over a longer duration if there is 4mm of wear on the followers. Try buying new ones if you can stretch to it, and come to mention it, buying new ones for the standard cam will probably bring back a few missing ponies. Costs: Cam: ?25

Inlet
The simplest and cheapest way forward is to find yourself a 1.3sr. It must be a 1.3 and not the 1.4 as they are very different. Youll need to take the carb and its manifold. The manifold will fit on the 1.2 head, and hey presto, you have a twin choke. This isnt the ultimate solution, but it is a vast improvement. Cost is gonna be ?50 plus from a scrappy.

Now this should get you SR (ish) performance. Not a rocket ship, but it will be more fun to drive. There is a lot more to do, but realisticly, its not worth the extra expense. Dont overlook the brakes and suspension!

Insurance is a consideration. Youll need to declare the carb and exhaust, both of which will have minimal effect on your premiums, if any at all. The camshaft however will never be noticed. Id bet money on that.

This all adds up to around ?125 (not bad for a 15+ bhp increase), you might be able to get bits cheaper or even for free, some scrappies might charge more, so expect to shell out between ?50 and ?150. Dont forget about consumables such as head bolts and gaskets, coolant and most importantly youll need a haynes manual!


---------------------------------
Guide written by Mc

[freeman88]

whats the difference between a 1e carb and a 2e ? and mine is mk 1.2ilux+ with spi (nochoke) do you have to have a choke with the sr carb and inlet ? or is it just bolt on and off and attach normal cables etc? because ive seen a 1e carb and manifold ? help appriciated

[Steve]

The 1e is the early sr single choke and the 2e is the later twin choke, much better.

[burgo]

if you are going to change the cam then the best standard cam is the 1.4sr cam. although being as these are hard to find the next best thing is a gte/gsi cam

[Adam]

Just to add a bit of info, the cam change part needs changing/removing.
As a 1400Sr, GTE/GSi cam WONT fit a 1.2 carb dizzy drive.

Only a 1300 cam is a straight swap.

So if you want to run a 1.4,1.6 cam you will need switch to a 1400 dizzy/ignition setup.

whats the difference between a 1e carb and a 2e ? and mine is mk 1.2ilux+ with spi (nochoke) do you have to have a choke with the sr carb and inlet ? or is it just bolt on and off and attach normal cables etc? because ive seen a 1e carb and manifold ? help appriciated

This guide does not refer to your engine, yours is a spi, this guide is to 1200 8v carb engines.
Theres another guide kicking about somewhere for 1.2i's

[meritlover]

you should mention skimming 40thou off the 1.2 head to increase compressrion ratio. this makes a nice engine. also cut back the valve guides and remove the dangle berries from behind the valve seats. even a beginner can go this with a rotary burr and emery paper.
Adam, you can modify the distributor drive if you want to swap cams and keep electronic ignition. it is an easy thing to change.

[Stuart]

you should mention skimming 40thou off the 1.2 head to increase compressrion ratio.

I'd only do that if the head hadnt been skimmed already.... its ALWAYS wise to measure the CR when you start stripping/rebuilding the engine etc.

[OllieKing]

;

[matt_vaughan]

Right, been offered a 1.3 SR cam and followers for the 1.2 in mine.

I'm assuming there's some difference in lift, however, is it enough to justify doing the job?

[Stuart]

many years ago when Velos were running they swapped a 1.2 cam for a 1.3 cam and found 5bhp.... imho thats decent going for a little effort and £8 in a draper cam tool (saves head off antics)