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Piston/Cylinder & Camshaft Questions


Vehicle Information: Model: 911 SC; Year: 1978; Body Type: Coupe; Total Mileage: 145,000 miles;

I have a '78 SC, the motor (~145,000 miles) of which is currently lying disassembled because of 2 broken head studs. Today I met with the technician doing the rebuild to talk about pistons/cylinders and camshafts. From this discussion, I came away with the understanding that the technician's intention is to reinstall the Mahle pistons as they were removed, without re-ringing them. I stated my interest in JE pistons to the technician. My car's compression ratio is 8.5:1, and the possibility of using JE's 9.8:1 set intrigues me.We also discussed the camshafts today. I expressed a desire to explore a 964 or SC sport grind. With this background, here are my questions:1. Generally speaking, is it folly to reinstall Mahle pistons with 145,000 mi. on the clock without re-ringing them, given that a set of rings are only about $100.00?2. If I use the JE 9.8:1 pistons, do I need to make any subsequent alterations? (I'm aware that the higher compression ratio might necessitate stronger valve springs, and I'm hoping that the higher compression ratio will not require twin-plugging to avoid detonation.)3. If I use the JE 9.8:1 pistons, do I have to be concerned about valve clearance?4. Regarding the cam grind, and assuming the JE piston install, what would be an appropriate specification. (I am leaning in the direction of the 964 grind.)Any other pertinent thoughts and suggestions are greatly appreciated.Thanks, Gary S.

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