7:1 or 8:1 cylinder head?

[flow]

I have a S3 904xxxxxxx engine which from what I can gather should have a 7:1 compression head on it. It has been reconditioned and has extractors, so I'm wondering if who ever did that put an 8:1 head on it. The only numbers I can find on it are 568750 and 12G.

Is this a 7:1 or 8:1 head?

[TerryS]

My 88 is put away in the barn for the winter so I can't go and check, but I bought a reconditioned 8:1 head from Rovers North awhile back and I distinctly remember it being stamped with either just an 8, or maybe it said 8:1. it was up toward the front if I recall. It may have started life as a standard 7:1 head, but RN has hardened valve seats installed and new guides, and planes them to give 8:1
As you have extractors, do you have a Pierce intake with the 2bbl webber?

[flow]

Hi Terry.

Heres a photo of the manifold. Not sure what it is. But I am sure that that is a leaky Solex on it.

Is there any way to tell from that part number 568750 what sort of head it was. I've looked all over the head and there is nothing that looks remotely like an 8 or 7 on it.

Cheers
Jas.

[bamarover]

Based on what I could find when we were trying to figure out what our 2.25 petrol was is this: There is a flat spot in the middle of the head (front to back) at the base of the valve cover, about 1" square. I can see this area directly across from the carb in the pic you posted. If it is smooth and no number stamped on it, it is a 7:1 head. If it has the number 8 stamped on it as in the pic below (sorry the pic is a little blurry - hard to hold light and cmera still!), it is an 8:1. That is assuming someone has not rebuilt it already and upgraded it and not stamped it!. HTH

[pickuprover]

That flat spot is assuming that when it was replaned to an 8:1 that they actually knew to stamp it. The head numbers would give you a clue, but if the head has been replaned (like mine has from 7:1 to 8:1) you would never know. There is a way of figuring it out by taking the head off and measuring it, but why one would go to all the trouble just to figure that out is beyond me... there really is no difference in parts/ setup other than timing, and I always do timing by ear (if you do not already do it this way, check out this site... http://www.bayourovers.com/trick19.html) it is the only way as far as I am concerned to get proper timing on these old engines. Any mathematical way does not take into acount worn/stretched timing chains, and other things....

[flow]

Thanks bamarover. I cleaned the gunk off it and found the illusive 7. So all I know now is that it is either a 7 or an 8. I'll do a compression test on it tomorrow. If is was an 8 then I'd leave it alone. If it is still a 7 then I'll get it planed.

Can you get any more than 8:1 from a 7:1 head? 100 thou off is it?

Originally Posted by pickuprover

but why one would go to all the trouble just to figure that out is beyond me...

This is no trouble really. As you can see I'm trying to sus out weather to pull the head or not.

P.S. Is that the standard intake manifold?

Cheers guys.

[pickuprover]

Looks like the standard intake to me.... and a leaky carb as well (although you mentioned that it was leaking earlier...)

Do your compresion test, if you get good numbers then I would just leave it, unless you think that there might be other issues...