If I have a 56CC chamber and I have the head shaved 0.100 I should have a 41CC chamber, correct?

What I am looking at.

56CC chamber milled to a 41CC chamber.
3.5" diameter head gasket.
0.40 compressed head gasket thickness.
Piston 0.185 below deck.
3.40 stock bore.
9.20 : 1 compression.

Will 9.2 run on 87 octane pump swill? This is a stock cammed (66 I think) 225 with a bbd super six.

TopHat

The Hpak duster does it without pinging, but you'll have to find a 'suitable timing curve for it (modify, drive, test, repeat)


-D.Idiot

At 39cc's I have to run 89 octain but mine is 30 over.

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Tophat,

My gasket is 039, milled .100, 42cc and I think is the .060 over engine. Cammed too of course with large valves, etc. Pinged all the time on regular to start. but runs fine on a dizzy recurved, as DI says, for my block, weight, rear end and so on.

I think it was DI recently who suggested a stock dizzy with a spring added from Mr. Gasket 928G as a starting point. My experience is that WAS a good place to start recurving. I am now up to 28 degrees mech and intial plus 22 with vac, total 50 with 10 BTDC to start. I had to braze slots to get a 9.1 slot length, running pretty good now but I need to work on the timing of the vac coming in. On regular now.

rock
64d100

Well it sounds like it will work ok. I just got back from dropping the head off for it's 0.100 shave.
Good info on a starting point. That Mr. Gasket 928G spring, how does it compare to the stock spring? Is it longer or shorter? Heavier or lighter? Just trying to get an idea of which way I need to go. I have a bunch of springs laying around but I'm not sure what they all came from.

TopHat