OMC head(s) question

[Lockjaw]

Is there anyway to tell how much a head has been milled. I found a 325638 head, but it looks like it has been decked, anyway to tell how much?

What would be a safe amount for pump gas? IS there a thicker head gasket that could be used?

Thankfully I can get the other side new, can I just mic the new one and compare to the old?

Thanks

[the witchdoctor]

Cc a good head, then do the math, and you will be able to tell pretty close how much was taken off of it.......

[B.Leonard]

If you lay an uncut head next to one that's been cut you may be able to see the diff. Just CC it to make sure, they can vary up tp 3-5cc or more since they're cast.

105cc is about the limit on 93 street gas
100cc for "spiked" street gas
93-95cc is a nice 155-160psi (50/50 race gas mix min)
91-92 Typical CCC opened up for a big bore
less than 90 needed to get to 180psi but it will SCREAM :)

Remember, any piston top mods will increase your CC vol rapidly.

-BL

On the gaskets... the new ones (Sierra) are .057 thick, I run those and cut the heads accordingly. No time to look for antique NOS stuff. The Pro Marine gaskets were .050 but even those are getting rare. Factory was .035-.050 I think.

[Lockjaw]

Ok well here is a tough one for me, how do you account for the spark plug? Do I put a plug in it to CC it, or what?


Also, what about the squish area, is that something I need to worry with on these? Its going on an 89 GT175.