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CC'ing Mac cylinder heads

Posted: Mon Mar 07, 2011 8:49 pm
by mcbob
In the 90 series and the super series of Kart engines whats the variation as regards cc capacity of there cylinder head chambers .

Re: CC'ing Mac cylinder heads

Posted: Mon Mar 07, 2011 10:42 pm
by Scott Kneisel
The only time I cc'd a 91 head was when I shaved it to make the hemisphere smaller for increased compression. The stock 91 head started at 7cc and I kept shaving until I reached 5cc. Had to take a lot off too, the sealing surface was pretty close to the fin base. I didn't measure exactly how much, somewhere around 0.075" I would guess.

This raised the TCR a couple points.

Never measured a 101, some 101's had larger hemispheres but I don't have one of those to measure.
The Mc49 and similar fixed head saws have a hemisphere volume of a little over 8cc.

Maybe someone else has cc'd a 101 head, how about it??
Scott

Re: CC'ing Mac cylinder heads

Posted: Tue Mar 08, 2011 12:29 am
by Tom Smith
The factory high compression Mc-101 head is 6.4cc. I've never cc'ed a stock 101 head. One nice feature about the factory heads is the top fin and the two bottom fins are machined shorter so the head shroud and the fins don't contact each other. They used the double rib casting for the high compression heads.

Re: CC'ing Mac cylinder heads

Posted: Tue Mar 08, 2011 4:25 pm
by mcbob
Thanks fellas

McBob