How much can you skim off a aby head?

[ross25480]

Hey guys quick question. What is the most you can get away with skimming off of a ABY head before the pistions clash with the valves? I have had to have 0.5 of a mm taken off of mine after my water pump gave up the ghost at Castle Combe. The last thing i want to happen is have it all bolted back together for it all to have to come to bits again so i can fit a new head. Come on guys blind me with your tec specs cheers all

[s2_southwest]

as little as possible i would say as you start raising compression which is not really a good thing with a turbocharged engine.

[Ross]

Surely this can be compensated for by fitting a thicker head-gasket, similar to what the big-power boys run?

[Mark Halligan]

Surely this can be compensated for by fitting a thicker head-gasket

You could do that, it works fine.

Here is what the manual says

[spink]

i have also heard of the valves being cut further into the head,but cant remember if that was S2 specific or not.

[s2_southwest]

you could do ross yeah, just saying if you can keep more material there all the more better. i have even seen almost solid metal spacers used on a nissian 200 with good results.

[S2central.net]

Both suggestions of a thicker gasket and valve cutouts are valid. Wasn't it Doug who did the valve pockets in his pistons to good effect - its a nice trick. I think he ended up with a non-interference engine if memory serves correctly... Can't remember what his static CR was for that config.


PAul