The Stovebolt Site Forums The Shop Area Engine Shop 235 head milled - how much?

I have a 235 head that has been surfaced and maybe more than once. Is there any way to measure to tell how much has been removed? Like a datum dimension from rocker arm pad to head surface?

I know that I could set up a CC plate and fill the chambers to measure but would rather find a quicker, simpler method.

I doubt that any "blueprint" dimension exists for this. There were at least 3 different 235 heads from 54-62, all with different combustion volumes and other minor differances. The production tolerances during machining were probably fairly wide, as the 235 was never a close-tolerance performance engine.

As a machinist once said to me "heck, you could cut down this head with a hacksaw and you still wouldn't have valve-to-piston contact."

I've never even been able to find a listing for what the stock chamber volume is supposed to be, for any head casting #. Supposedly every .005" off the head removes about one CC from the volume. I'm having my '54 head CC'd, and its been shaved at least .040". I'll post the results here.

chip

Just learned this tip at Calif Inliners picnic, from 261 Guru Mike Smith. Flip the head over so you're looking at the surface, look at front left corner, will be below the front stud where exhaust manifold bolts on, but at the deck surface. There is a very small slightly slanted number pad, maybe 1/4" x 1/8" for a 'cast' code, my 53 powerglide head on the work bench has the code 'A21'. What does the number mean, who cares, just use this as a clue for estimating how much has been milled off. If the little numbers are virgin perfect, the head has not been milled. Compare this area on an milled head to a untouched head to estimate how much has been removed. Please post what you find. Mike says he found this area on 235 and 261 heads. Happy hunting.