has anyone compared the later and earlier 1.3 mk3 heads (with the early ones having 8mm valve stems, and the later ones having 7mm valve stems).

looking at the valves side by side, I'm thinking that the later valves will flow better and are similar in shape to some early ones that I've modified (apart from having a 30 degree back cut in them).

if the ports are diffrent too, (I dont know as havnt seen a late mk3 head), there may be a performance benefit too, (although I'm guessing that its only likely to be a couple of bhp).

anyone have any ideas on this?

sounds interesting!! shame my gts on a H plate........

bought a L plater GT so what you reckon, have you researched this more mate?

no I was just just mentioning something I'd seen with different heads. although if anyone out there has any technical info, they are keeping quiet.

I had a Early GT head and a 'ported and polished' late head side by side and the only major difference I found was the valve stem thickness, which we talked about on another thread a while back.

I made a thread about asking the differences but I cant find it now

Although I think that me and you are the only people on the entire forum that agree not all n/a 1.3 mk3 heads are the same.

i never knew this sounds interesting.

Learn something new everyday.

Anyone find out more bumf on this . I allways was told that all mk3 heads are the same.

not many heads on other VWs can be used for BHP gains is there?

My ABD head has huge ports. They already match the inlet gasket.

Standard?

Is the ABD head better than the 1.3 head?

Yep, off the shelf. Don't know if it's any better. Might be too big for the 1.3.

Wasn't thinking about for a 1.3. I've managed to get hold of an ABD and was thinking of getting a 1.3 head to go on it, but may as well just use the whole ABD lump, head and all. Dump in a GT cam.

Not too sure about the best choice for an inlet manifold. Apparently GK ones are a straight swap for spi (will be keeping spi for a while) systems.

Optima you are welcome to an M-Reg spi head if its any use to you! (And if you want to help swap engines thats fine with me hehe)

ahh thanks for the offer, but I find it hard enough getting motivated to work on my cars.

with normally aspirated 1.3 mk3's I'm thinking that 1.0L heads fitted with 1.3 inlet Valve seats and valves and ported will probably flow better than 1.3 ported heads for moderately tuned engines, but somehow I dont think anyone is likely to build a head like that to try it.

I'm gonna be building up a head for either an ABD soon. Still haven't decided how far I'm gonna take it...

Although I think that me and you are the only people on the entire forum that agree not all n/a 1.3 mk3 heads are the same.

From what I've seen the port shape and head castings seem to be the same amoungst 1272cc lumps. Been looking at valve guides today, and as Dom says the later n/a engine valve stems are 1mm narrower (7mm instead of 8mm), but use different valve guides to compensate for this. G40s all have the 8mm stems, which is probably a good thing for reliability.

I had a Early GT head and a 'ported and polished' late head side by side and the only major difference I found was the valve stem thickness, which we talked about on another thread a while back.

I made a thread about asking the differences but I cant find it now

Although I think that me and you are the only people on the entire forum that agree not all n/a 1.3 mk3 heads are the same.

that ported head is early spec. came off a J plate car.

So if its not late/early spec then how do you know which size they are?

and I know H-reg (1991) is definately early spec but what counts as 'late spec'