Well, I’ve been away from forums for while after a few (massive) life changes but thought I’d give an update. The car was built, mapped and driven all of last year and is now undergoing a big strip down and rebuild 😂

All of the old alloy work has completely gone and is currently being re-designed. And we also have a new engine to build.

A lot of people have been messaging me since they found out what head I’m using on the build, most of them asking how much to sell it. So, a little more info as it seems to be scarce. I can’t even tell you if this head is standard as Ford used them or has been ported by a third party as no one has the information and finding another to compare it to would be difficult.
Firstly, this head is rare. Only a handful seem to be in circulation. I know of only two in the UK, one being mine. One in France and one in Hungary. There are also, I’m told, a handful in the USA. Ian Howell of Area Six has only ever seen one in his career some years ago and he’s one of the top Zetec Turbo engine builders out there. Some tuners I’ve spoken to didn’t even know it existed.
This head goes by a few names. The “Initial Development” “First Casting” and “Zeta Prototype”. One thing’s for sure, it’s no normal Zetec Head. It should also have a different cam cover, unique to this head, but unfortunately I don’t have it. That’s also why although a regular Zetec cam cover fits, the central mounting holes between the spark plugs are drilled in different locations.
It’s also been referred to as a “Motorsport Head” as Cosworth did recast a batch of heads with more material around the spark plug recess as a few early heads cracked on the works cars. However, as far as I’m aware, this head was never used for motorsport by Ford, although it is sort after by American drag racers.

Inlet Side- the Inlet ports are huge in comparison to a standard Zetec Silver Top head. The ports measure 66x34mm compared to the normal heads 46.5x30.5mm. The bolt pattern is also different as a different inlet manifold was used with these heads and a standard manifold won’t bolt up. This includes my genuine WRC inlet manifold, confirmation that this head would not have been for WRC. It’s a good manifold...if you can find them. They are just as rare as the heads themselves.
The head also features a threaded port below the main port which jets directly into the combustion bowl.

Exhaust Side - exhaust ports are also larger, but not quite so significantly, which is strange as at high power levels it’s the exhaust side which struggles rather than the inlet. Ports are 41.8x34.5mm compared to 39.8x33mm. Exhaust manifold stud spacing is the same on both heads.

Casting - the head has no Ford casting logo or date stamp anywhere and it’s a much “cleaner” looking casting. The Zetec code “958M 6099” is cast on the inside rather than the outside and a hand stamped number 28 along side a cast “B” is between 2-3 spark plugs. The casting it’s of is thicker in places, sometimes by as much as 4mm, although, the material around the cam followers is the same on both heads. It uses standard Silver Top sized cam followers, camshafts, cam caps etc. The casting has less rough cast marks but unsure if these were removed at a later date. There is more material around the spark plug seats and this area in general. Valve seats are also larger on both inlet and exhaust for bigger valves, 33.5mm inlet and 30mm exhaust on this head.
The combustion chambers on the heads are also slightly different shapes. They are perfectly round and measure 84.7mm across on the “prototype” head and being squared off 81.8mm on the standard head meaning the compression ratio will be different.
It’s also hard to tell in the pics but looking into the head through the thermostat housing hole there is more meat on the casting around the valves on the “prototype” head.
The water jackets openings are also different. Larger on the outsides but smaller through the centre and feature and additional cut out for a jacket on the bottom left as view on the picture.

Both heads share an identical thickness of 133.36mm.
I’m going to remove the valves and springs from the standard head and compare the bare weights at some point.

some pics

There’s a lot of bad/mis information about the Mountune CGI Zetec blocks. One of which is their weight with some claims of them being 20% lighter than a standard road block. Here are the two weighed (crudely on a bathroom scales) back to back. The Compacted Graphite Iron Block coming in at 31.6kg and the standard Silver Top block 34.5kg, that’s 8.4% lighter. Although, the CGi block does have extra cast material at the rear in the form of the oil filter take off, whereas the silver top does not have this. I suspect a standard Black Top would be slightly heavier again putting weight more around 10% lighter. Still, 3kg is a lot in real terms when the block is destined for WRC and the fact the CGI block is significantly harder/stronger than a standard block...or is that just another myth.



I’ve had a spare engine for about 8 years now and always planned to use it as a base for a Zetec Turbo in the future. It was apparently from a 20k mileage auto (aren’t they all...) but the original block paint and overall condition got my attention and I bought it. Turns out, he may not have been lying. Utterly spotless engine and still all original dimensions.

Although I now have a much better CGI block and only needed the end plate and oil squirters for my build, the crank is far better than the one supplied with my other engine and it’s a handy spare block on its original 84.8mm bore.








Also stripped down my dry sump pump and gave it a good clean. Good job, too. It was full of grit!

Glad you’re back on with this pal. Typically detailed write up. What’s your plan with the head? With inlets that size it’s going to need opening up on the exhaust side surely? Do you know anywhere that can x-ray it for you? It’ll give you exact dimensions for porting? Could Rick Wood guide you?

I used a Mondeo Rev counter and Cosworth Speedo. Both work like a dream.

i have contacted someone about re-casting the head. Just waiting to hear back, so see what happens. I think I’m going to use Pectel T6/2000 management so trying to find original YC sensors at the moment.