9 replies to this topic

[samt88]

Hi guys,

I bought a 12g295 head for my 998cc A-series. To cost me about £80. I've given it to a machine shop to sort and they gave me a quote of around about £600 for porting/polishing etc and getting it all fixed up. This was a tad more than I was looking to spend.

I was therefore wondering a couple of things. Firstly, would it be possible to port and polish myself, as this was the main cost, given I have limited experience or is it not worth bothering? Also, are there any lower cost alternatives that would be almost as good? (Someone on here said they got a ported refurb head for £220)

Cheers,

Sam

[Cooperman]

Rob Walker Engineering in Witney, Oxon, would do the complete head for c.£400. That would include gas=flowing, re-valving and skimming to get the CR correct. You need to do the measuring to determine what size the combustion chambers need to be to get the CR you want.

Alternatively just clean it up and get it skimmed to whatever you measure it to need to be.

In all honesty, for a classic car the main thing is that it should simply run nicely in a 'classic performance' way. It won't be like a modern car whatever you do to it.

[samt88]

Oh cheers, Cooperman. Yeah I know, but I'd like that little bit of oomph to get past a lorry on the A303!

[jaydee]

Mr Walker makes excellent cylinder heads

Alternatively you can ask AC Dodd or Turbo phil for a quote, thy're both on here

[Cooperman]

The 998 Cooper in standard form gave 55 bhp.

You can replicate a 998 by fitting the 12g295 head, a better cam, the correct compression ratio and a Cooper exhaust and induction system.

Now 55 bhp is fine for a classic car used on the road.

[ejs-1995]

The 12g295 is definitely worth it! I have just fitted a stage 3 12g295 and the car is transformed! The car pulls so well now, it keeps up easily with my friends 1.25 fiesta and 1.4 polo! It's definitely worth the £400. Once rolling roaded I found the fuel economy was also better

[samt88]

So if the head is gas flowed and a new cam etc fitted surely a bit better than 55hp should be achieved?
Oh and what does a stage 3 head mean? Mine had stage 2 stamped on it...

[ejs-1995]

From what I understand stage 3 is that the head was ported and oversized valves were fitted and also skimmed. I'm unsure about stage 2 though



Oh and 55bhp may not sound that much, but it is pretty sweet in a road car

Edited by ejs-1995, 01 November 2013 - 10:57 PM.

[Cooperman]

All the 'Stage xx' business has little meaning and is really a marketing term used by different people to mean different things.

To improve a 12G295 head is quite simple. You can fit slightly larger inlet valves, improve the combustion chambers by de-shrouding the valves a bit more, removing most of the valve guide boss in each inlet & exhaust tract, re-shape the inlet tracts slightly, remove all the sharp edges and roughness in the inlet and exhaust ports, match the ports to the inlet manifold and, most important, get the compression ratio to a figure which will work best - around 10:1 seems most popular.

A better cam such as an MG Metro or Kent 266 will improve it and allow the re-worked head to release the potential and decent inlet manifold & carburation like a pair of HS2 carbs on a cleaned up manifold together with a 3-into-1 ex. manifold and original size Cooper 998 exhaust will release probably 60 bhp. A new distributor will be needed to cope with the different engine spec.

[F1L8EY]

ive just had my 1098 head skimmed de coked and valves re cut for £75 paul inch in plymouth, he specialises in a series and races them too. might be worth a call, even with postage he sounds cheaper