How much can you plane 2.8 heads?

[Arns85GT]

I have a Fiero 2.8 and I'd like to raise the compression. The heads were redone and the faces lightly re-milled last year, however, I need more compression.

How much can be taken off the heads without valves hitting, and what compression ratio will result when you are talking about a stock 2.8 set of heads?

Arn

[Syn]

time for pistons bro, do it the right way

the iron heads increase compression from what i've read. how much idk and if u have aluminum heads i am not sure what else would needed to be changed

but i'm maken plenty of power with a c/r of 8.8:1

[sil]

i think the most you ever want to plane heads is .020, but my machinnist said .012, this is due to the angle changes at the intake to head surface

[prophiseer]

GM's tech info states no more than .010" - prob for the same reason as stated above.

The machine shop we deal with has claimed they can go to about .020", but will also require the base of the LIM to be decked a similar amount

[Syn]

u didn't say if ur heads were iron, but u can try useing the iron head 3.1 head gaskets because they r thinner

[Ortie666]

Or use 3.1L heads with the 3.1 gasket on those 2.8L flat top pistons for a good 12.5:1 compression.. then i dont think you will be complaining about wanting more comp. rather more money for racefuel so u can drive to get grocreys

[Superdave]

I agree with Ortie666.. switch to the aluminium heads... Gen3 FTW!

[Arns85GT]

Switching to aluminum heads means a whole lot of dough and a whole lot of inconvenience on the engine. I have the Edelbrock Torker II intake and a Holley 390 carb. The exhaust manifolds for a Fiero have to be special do to space limitations. No room for S10 style headers.

I am trying to avoid the expense of pulling the pistons and doing new pistons and rings. Does anybody know what compression you end up with at .020 shaved off?

As for the gaskets, I've been wondering about them too. Would copper gaskets be thinner? And would they bump the compression?

Arn

[bszopi]

60V6 CR Calculator

You'd just have to try to determine how much the volume of the head will change with a.020" taken off. It shouldn't be too hard to guesstimate if you can determine the area of the chamber at the surface of the head. Take that number times .020, convert to cc's, then subract from the stock volume.