Flat Milling a GM 76 cc Head

[Verdoorn Racing]

I'm wondering how many cc's can be removed from a 76 cc head by flat milling before the intake won't seal? Rules state that the intake side of the head can not be machined and can not helicoil the bolt holes on the head changing them from 3/8” down to 5/16” so you can move the intake around. Just exploring the new optional IMCA stock car engine rule.

Thanks
Jeff Verdoorn

[hpontap]

How about machining the intake itself to match the heads?

[Verdoorn Racing]

Can't touch the intake either.

[parrot69777]

I have chased this idea around myself. The most you can flat cut a virgin head is around .030 and still get the bolts in the intake. Even if you do this, put in a shim head gasket, two valve relief piston, 0 deck height.....you might get to 10.5:1 if your lucky.

Even with a 500 cfm carb....I don't see how this engine is going to be a big time winner unless your on a 1/4 or short 3/8 and it is black slick. I mean there are guys running 388-430's with 14.5:1 compression with full ported heads and most of those 350 carbs flow as much if not more than a 500 already. It's basically putting an open late model engine on a 390 carb vs an IMCA late model with 10.5:1 ompression.

[stockcar5]

i agree it will be hard to keep up with the 350 motor. on our dyno the best b-mod motor made 360tq and 370hp. best stockcar motor was 390hp and 490tq. gonna be hard to make that up even with another point of compression.