12G940 1275 head had a combustion chamber size of 21.4cc. Your limiting factor
might be when you have valve interference with the pistons or when you run into
an oil delivery gallery. CR was a factor of how much dish was in the piston
top,
not a variable combustion chamber size.
Paul A
Glen Byrns wrote:
> I'm not sure about the minimum or original head thickness, but I believe
> that the high compression head had a combustion chamber volume of 19cc and
> the standard head is something like 23cc. I think its covered in the Clymer
> manual.
> A real perfectionist will check the volume of each chamber carefully and
> ensure that the volume is identical for all four.
> With the valves in place and plastic modelling clay filling in the spark
> plug hole in a way that follows the curves of the combustion chamber, I
> smeared grease around the perimeter of the combustion chamber and placed a
> piece of plexiglass over the chamber. I then injected water from a
> syringe into a small hole in the plexi and determined exactly how many cc's
> each chamber held. The PO was obviously anal-retentive, as they were
> identical to a VERY tiny fraction of a cc. He said that is how you get
> equal power from each cylinder and improve the smoothness of the motor.
>
> Regards,
> Glen Byrns
> '59 bugeye
> '59 Morris Traveller (Winifred)
>
> > List
> >
> > How much can you safely skim off a stock 1275 cylinder head?
> > And does anyone know what the original thickness is supposed to be?
> > Mine currently mics out at 2.745" (almost 2 3/4)
> > My machinist also asked what the head CCs were. I guess 1275 was not the
> > answer he was looking for.
> > This is a ported head (thanks chuck) and I don't want to have to search
> > for special gas to make the car run.
> > Any input ot BTDT welcome.
> > --
> > Frank Clarici
> > Toms River, NJ
> > 2 Sprites, 2 Midgets
> > http://www.exit109.com/~spritenut
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