Hi m8

I tend to take my engine to pieces an awful lot, so have become a bit of an expert on the matter LOL!

I am running a similar level of power to you at the mo, and to be honest, I managed to blow a Group A gasket in record time (10k) but I am pretty hard on the car. If you want a bit of extra security, then you might want to go for a Multilayer gasket. I went for the Cometic one. Not generally considered to be the best, but reasonably priced compared to the Genuine WRC multilayers. I have bascially been very pleased with it, though you need to ensure that both block and head are very flat, as it is not as tolerant as normal gaskets. DONT USE ANY SEALANT WITH THEM. I made this mistake, and cost me a gasket. Lesson learnt.

As far as the job is concerned, I have a 2WD, but all is generally the same.

To take head off the cosworth is generally considered to be an easy job provided you know the best way to go about it. The easiest way is to take off the head complete with the exhaust manifold, inlet manifold, tubro etc complete, and then dis-assemble on the bench. This is how I do it, and it saves a bucket load of time.

The problem is that the head cannot be skimmed with inlet valves left in place, and this makes the job a little more time consuming. As such you will need to use a special tool (valve spring compressor) to remove the valves on the inlet side only. This will mean a bit more of a job than just taking head off.

Once skimmed, it is really a matter of putting it back together in reverse order, making sure everything is as it should be. The rules for cossies is the same as other cars. All surfaces need to be suitably prepared and left in good order before re-assembly. Also, you need to know the tightning torques, order of bolts etc.

In addition to the Gasket, I would suggest the following:

Either new head bolts or pref. ARP Stud and Nut Kit
Inlet Man Gasket
Exh Gasket
EGT Gasket
Thermostat Housing Gasket
Cam cover Gasket
Cambelt

I would also strongly recommend that you replace as a minimum valve stem seals on all 16 valves. This is a job that requires the head to be removed to be carried out, and you will kick yourself if they fail later on. Also check valve guides.

If money is an issue, and you have some experience with engines, then you could consider taking the head off yourself, taking it to a friendly garage, to strip head, do necessary work including skim, then re-fit yourself! (making sure that all torques are correct)

This is by no means a definative guide to changing the head gasket, but should give you an indication of what is involved!

Cheers

JJ