Cylinder Head Developments
Cylinder Head Developments
56 Sherwood Road
Aston Fields Industrial Estate
Bromsgrove, Worcs. B60 3DR
Tel: 01527 870472
Andy Weston

Frequently Asked Questions

If you have a question you'd like to ask about engines and/or performance, then feel free to e-mail Andy at the address below and we'll post our response on the website as soon as possible.


After seeing plenty of MkII Escorts with Cossie engines in Classic Ford I want to do the same thing. I don't want to run it with a turbo though, I want to run it on twin Webers. Is it simply a case of removing the turbo and fitting new manifolds for the carbs, or will I have to do work to the internals of the Cossie engine?

Yes, if you want to run the Cossie as a naturally-aspirated engine, there's quite a lot of work to be done. The compression ratio is governed by the crown height of the pistons so they'll need to be replaced to bring the compression ratio up to the right level. These are available off the shelf and any good engine builder could supply them for you.

Next on the list, the cams will have to be replaced. People fit Cossie engines, fit carbs and then they're surprised that it's as flat as a fart. Turbo cams have a very short duration and low lift - the standard Cossie cam has a duration of approximately 240 degrees, the naturally-aspirated cam for the same engine gives 278 degrees duration. You won't get enough fuel/air into the combustion chamber if you leave the turbo cams in and the engine will never give its full potential

Finally the head. The inlet ports need to be opened up, as the turbo only needs very narrow ports. That's the basic requirement to get the engine to work well but you can go as far as your pocket will let you. There's loads available to tune the Cosworth engine now and the parts don't have to come from Cosworth - which is good as they can be very expensive and hard work to get hold of.

You can spend anything from 400 to get the basic head work done up to a full race Group A-spec, for at least 4,000. Then you're looking at the rull race monster head.

One last thing to bear in mind when tracking down an engine for the transplant is that many of them will have already been modified and subsequently used hard by now. The Cosworth head like all aluminium heads is very vulnerable to mistreatment. Over heating in particular can cause problems with warping

Cossie heads can only be skimmed two or three times - you take 0.005 inch to 0.010 inch off them at a time. If it's been skimmed three times, you can't take any more off. Be careful of what you're buying.

More FAQs ...

Need help? Contact Andy Weston:

Tel: 01527 870472 (National)
Tel: +44 1527 870472 (International)
E-mail: cylinderheaddevelopments@gmail.com
On-line: Contact Form