Thanks but no thanks chris, theres a long ways beffor I mount my head with lots of work to be done.

I've just had a look at the block and as it turns out the smaller holes are simply sized from the water galleys on the block rather than the ones on the head, so it doesn't really matter if the gasket ones are smaller or bigger. I'll keep them as wide as they are, referencing the galley sizes from the head rather than block.

Thanks for that Dave, better to be safe than sorry.

the difference in gasket to actual coolant passage size may be deliberate, to create a restriction to flow, keeping the coolant in contact with the galleries longer to aid heat transfer.

Cheers
Dave

29cc? Mine is 19........ it's as flat as a pancake, you could just about have a shave with the lip that has been left over from all the milling.

Connor,

Do you want a gasket? I'm getting mine machined up as soon as I hear back from the cheapest laser cutter- GX custom gaskets mate, good opportunity to drop your comp ratio.

GX and H89 are both 29cc stock

My oath it's a rip off.

I need a 3mm gasket though so I'm doing it all the long way. Just did a bit of checking, I reckon stock gaskets are shyte as a reference so I scanned the head and drew my own. Finally put the Uni A3 scanner to some real use!





EDIT: The biggest inconsistency in the off the shelf gaskets were the openings for the coolant circulation....I mean the holes in the gasket were about 50% of the size of the actual vessels in the head. I wonder how many heads got hot because of this?

The H89 chamber isn't as good as the GX one. It's a bit less heart shaped, and a bit deeper.

Also, $104 is a rip off! I got mine for between 50 and 70 (Can't remember exactly) AND it had to come from Aussie too!

I've finally drawn up the gasket to suit the head, the original one I had drawn up using a off the shelf gasket [as a reference] was surprisingly inadequate in terms of clearing the vessels of the head.




Basically rustling all the quote-requests together now.

Dazza thats the H75 head more commen on the "econamy" a14's. most a15's came with the H89 witch has the same chambers but larger valves then the GX head. The advantage of a GX head is the aproach angle and lack of a water galery over the intake ports.

I think in a street going 1000 this motor will still move it along quite nicely!

If I change the head I'll have to spend a mint getting it ported and match ported to the manifolds. Cost is pretty significant here.