Cutting heads

[67racing]

Trying to find out how much I would need to cut off a set of stock 2.5 heads, to make them 34cc heads. They are 39cc now. Thanks

[rock]

It probably depends on the head as in c1, c3, c5, etc.

Rock

[67racing]

I will check when I get home.

[rock]

I was just saying it depends on the head. I don't have the answer however there was a thread a while back where someone posted the info you want. I will try to look tonight to see if I can find it.

Rock

[67racing]

They are C3 heads. Let me know if you find the other thread. Thanks

[Umassot50]

If you know the bore size some simple math will calculate the volume of pi(r squared)h. This will calculate the volume of the cylinder(disc) of volume you are removing from the combustion chamber. You know the volume and "r" the radius of the bore. h will be the height of material to be removed ie how much to remove from the head. Solve for h. Use correct units. Radius in centimeters if you want volume in cc ( cubic centimeters).

[67racing]

Bore size is 3.50"

[smythe302]

Is the head chamber the same diameter as the bore?

[David - WI]

https://www.screamandfly.com/showthread.php?90388-18789-C3-Heads&p=730979#post730979

[HStream1]

Those heads should be 38cc not 39cc. How did you cc them? If you didnt use a burett and a plexi glass plate greased to the squish band with a hole for filling you are most likely off in your measurements. BUT!! Basic rule of thumb is for every .010 ths removed the CC diminishes by .7cc. So there is never going to be a exact amount of removal because the Chamber walls aren't perpendicularly straight vertically to the bowl and face. The only way to do them correctly is to use a Burett and a plexiglass plate to measure the chambers volume. I use a surface gap plug with the ceramic broke off and epoxy applied to prevent leakage. I also use rubbing alcohol with food coloring that makes it easier to read the burett.

[67racing]

Thank you

[TEXAS20225]

merc heads had two ways of numbering late c3 had smaller dia chambers then the earlier c3 and more cc, it was the same on all numbered head c2,c3,c4,c5 early and late were different dia chambers late heads smooth early head had the horizontal bars cast in the heads across the top 9 on each side of plug holes i got a killer set of 34 cc head un run since cut Jame perry did the work after jay smith cut all the marks in the the be bling heads go a squish cut in them they are un painted promax head (gray) 250 plus mail