Hello...

Is there a limit on how much surfacing that can be done on a cylinder head and how do you measure that distance?

Thanks!
Al

No, think you can go up to .100" flat if you want to really cut to the max. AND then cut everything else, plus new shorter P/R's!!

A 100 cc closed chambered large oval port head should go to 90 cc's at this much cut so would make a dandy flat-top piston motor compression ratio-wise, imho...

What's everybody think??

pdq67

I guess this is a pretty bad question. I was just wondering this because I was thinkin' of buying a spare cylinder head and wanted to make sure it wasn't over any limits. Just in case I needed to use it some day in the future.

Thanks pdq67 for your input. graemlins/thumbsup.gif

Regards,
Al

What are the datum or reference points for measuring to see if and how much a head has been milled?

You can see the thickness of the decks around the water holes, but not being a big time head buyer, I don't know what stock thickness would be.

Exactly Ron. Thanks for the help with the question. smile.gif

Al

You really can't unless you have alotta experience here b/c of being the Machinist that mills them.

The rough castings get spot-faced for the lower/outer head bolts by the exhaust manifolds but I am not sure anybody has a good handle on what the spec. was for this thickness, top to deck???

Anybody got an idea???????

pdq67

Glad to help Al.. smile.gif

I expected?? that the machinist must turn the head up sidedown, and mount it to the bed of the milling machine/grinder or whatever is used to surface the head. There must be a location on the casting for mounting reference, or so I would have thought....

Is there a machinist who can speak up here?

I have never heard of a Datum measurement for SBC or BBC's. I have seen people measure the thickness of the head across the short head bolt holes, but that is only to give a comparitive thickness before and after. The only way I know is to look at the surface of the head to see if it looks like it has been cut, and also the thickness of the head in the water jacket area. None of these are good ways the check for the thickness. Sorry no good answers from me. It is however easier to notice on SBC, because of the small water passage on the outside of the cylinder that is very shallow and it is easier to visually compare.

Sorry that is all this 'has been' machinist can offer. ;)
Good Luck.

Thanks all. I would have thought there to be some kind of max you should mill like there is on a brake rotor. Maybe there isn't and it's all dependent on the block, head gasket, and valve travel...? I don't know. I've gathered though that it is very hard to determine without having a machinist inspect it.

Regards,
Al

:cool: