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964 piston
Posted: Mon Dec 06, 2021 7:42 am
by Bob
Are these 100mm pistons standard 964 if so does any one know what compression ratio I should have .heads are 3.2 so is case with solex cams and pmo cards.
Re: 964 piston
Posted: Mon Dec 06, 2021 9:57 am
by MBEngineering
HI Bob
I take it you are trying to fit 964 pistons and cylinder to a 3.2, with the 3.2 heads, the 964 runs 11to1 CR with knock sensors, the CC of the 3.2 head is larger, I would have to check the CC of both heads to see the drop in CR
if you are using the 964 cylinders, I take it you know the stud spacing is smaller on the 3.2 and you will have to mod the cylinder in a mill to make them fit the 3.2 studs
the job is do-able with some work, you will have to check the hight of the piston pin, un-less you are fitting the 964 crank in the 3.2 cases
regards mike
Re: 964 piston
Posted: Mon Dec 06, 2021 4:04 pm
by Bob
Sorry I'm try to upload some pictures engine has been converted but awhile ago and I'm rebuilding it and want to check what's been done etc
Re: 964 piston
Posted: Tue Dec 07, 2021 3:39 pm
by Bob
MBEngineering wrote:HI Bob
I take it you are trying to fit 964 pistons and cylinder to a 3.2, with the 3.2 heads, the 964 runs 11to1 CR with knock sensors, the CC of the 3.2 head is larger, I would have to check the CC of both heads to see the drop in CR
if you are using the 964 cylinders, I take it you know the stud spacing is smaller on the 3.2 and you will have to mod the cylinder in a mill to make them fit the 3.2 studs
the job is do-able with some work, you will have to check the hight of the piston pin, un-less you are fitting the 964 crank in the 3.2 cases
regards mike
Re: 964 piston
Posted: Tue Dec 07, 2021 3:41 pm
by Bob
Managed to get picture on are these standard pistons?
Re: 964 piston
Posted: Tue Dec 07, 2021 5:31 pm
by MBEngineering
HI Bob
looks like a Std 964 piston,
I would clean the top off and check to see if there is some machining for valve pockets on the piston, to get the C.R. up,
did you check the valve timing before you striped it?
regards mike
Re: 964 piston
Posted: Tue Dec 07, 2021 5:50 pm
by Bob
Not checked it yet 1 side is stripped. There was a electric fire over 1 side carbs were sent back to pmo to be rebuilt. So some was stripped by others but I want to go right though it
Re: 964 piston
Posted: Sat Jan 01, 2022 4:58 pm
by Bob
Cam timing is coming out at 4.2 and solex cams are 4.2 to.4 .6 do engine builders always stick to porsche set over laps ?
Re: 964 piston
Posted: Wed Jan 05, 2022 7:53 pm
by Bob
ive cleaned up pistons and barrels on the top of the piston is E on bottom 100p 36 + w6 +
on the cylinder there is a 1 then a 2 then a 5 in a triangle could any one tell me what the wear limits are on these