CC'ing Mac cylinder heads

[mcbob]

In the 90 series and the super series of Kart engines whats the variation as regards cc capacity of there cylinder head chambers .

[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

[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.

[mcbob]

Thanks fellas

McBob