Pinto Head cc question

[Enea]

Hi, If anyone has any experience on this....

I have milled a pinto grp1 spec head 0,15mm (6 thou), It was 43cc before... is too much to assume a full CC of volume taken away? maybe half? or too little to have any effect?

I'm just curious, it won't really change the final build spec.

[Miniliteman]

From memory that would take the CR up 1/10 of a point. So if it was 9.2 it now will be 9.3 . Graham will know best.

[Graham]

6 thou wil have little effect

[Miniliteman]

If the head now is 43cc then taking (another) 0.15mm off does increase the CR a bit more than 1 decimal point.

According to Graham a 43cc chamber equates to a CR of 10.9:1 .

[Graham]

If the head now is 43cc then taking (another) 0.15mm off does increase the CR a bit more than 1 decimal point.

According to Graham a 43cc chamber equates to a CR of 10.9:1 .

that depends on many factors, i have an engine with a 42cc chamber on that engine its 11.3

[snapper1]

How for the piston is down the bore and gasket thickness also has a big affect on the final compression ratio

[Miniliteman]

You would have to measure everything to get a definite CR number but the point is that skimming "just a bit" on a standard head has little effect, doing the same on a head with a 43cc chamber means going up .4 of a ratio.

[Enea]

thanks for all the replies, I asked about the CC's of the chamber, not the CR

CR it will be between 11.2 and 11.4, have to check valve clearence.

[Miniliteman]

thanks for all the replies, I asked about the CC's of the chamber, not the CR

Yes I know, but I don't have an answer to that question so said what I did know.

[Forest_rallying]

thanks for all the replies, I asked about the CC's of the chamber, not the CR

CR it will be between 11.2 and 11.4, have to check valve clearence.

Either way I shouldn’t worry about it to much.