1.2 head on to a 1.6 MKII astra bottom info....

[robb]

As the title, anyone know or have any experiences with 1.2 heads to the 1.6 MKII Astra block?

Need to know about valve clearance and head gasket info. Also I am not sure wether the 1.2 head has big enough valves to allow enought flow.

Cheers

[Stuart]

it will require bigger valves to make any proper difference

[robb]

I thought it would, it's for a bloke who is a bit of an airhead and doesn't really have much of a grip on life, I'll tell him to just fit the 1.6 complete then.

Thanks

[Snowface]

what about compression ratio's?

12/13:1 or something?

[johnny27]

I take it the 1600 is carb fuelled? If so it may be worthwhile thinking of fitting larger valves, as the 1.6 head has a very restrictive flow, little square useless ports like the SPi heads, 1.2 head a good flowing head with larger ports and straighter flow to the valves seats. Combine that with greater compression and 1600 MPi valves you might get a reasonable difference nothing major though. Not 100% sure if it would be worth it but no harm thinking about it. BTW you'd have to use the 1.3SR inlet manifold to match the ports and to use the astra pierburg twin choke carb, which i think most of them had.

[Stuart]

umm what you gain in compression ratio you lose in the pissy valve sizes.


and i was under the impression that the 1.6 carb head was the same as the gte head (non egr) but hey

[robb]

It seems that it is not going to be any different. So instead of him splitting the engine I'll tell him to leave the head on. And we are using the 1.4 manifold and a Webber 32/34.

It's an Astra MKII block and head, is the head different to the GSi? I know that is supposed to flow better than other heads.

[johnny27]

I used to have a 1600 carb astra, the ports are defenitely the same as the spi ports which i think is also the same as the 1400sr ports, poor flow.

[Snowface]

camb, the other day you said that a 1.2 head on a 1.6 gte block would be too high compression.

But a GTE block is same as a standard carb block.

so how can you put a 1.2 head on a 1.6 carb block and not GTE?

[gaz_master]

ive got a 1991 astra block with a 1.3 sr head on seems 2 go fine but dats got similar ports on

[_JH_]

aren't the gte pistons different to those found in the carb 1.6, causing higher compression?

[Stuart]

the compression "could" be too high unless you know what your doing.