Time for Overhaul???

[porschedude996]

I’ve the engine out of my 911SC (3.0), primarily for transmission overhaul. And planned to cleanup the engine and install tensioners.

I borescoped the engine and I really don’t like the amount of wet carbon buildup. Looks heavy on the exhaust side and think there’s a fair amount of ring ridge.

With over 149,000 indicated, and came to me with a worn out speedometer (odometer didn’t advance while test drive), i’m thinking it’s time to start an overhaul.

Thoughts anyone???

[porschedude996]

Also, if the cylinders are beyond limits, and I need to keep the CIS, is it feasible to raise displacement (3.0 to 3.3) and 9.8:1 using pelican Part#: LN-PS100-011N? Maybe 964 grind on the cams? Since the CIS RUNS on mass airflow, would more air entering affect the fuel mixture, and drivability?

[PeteKz]

To go larger than 3.2 typically requires boring the case for larger diameter cylinder skirts. Also look at the M1 cams William Knight sells. They work well with CIS and use all available duration and lift without piston/valve interference. If you choose a different piston top shape, you can use a more aggressive cam, but that probably will cause CIS drivability to suffer.

The CIS matches fuel flow to air flow, especially a lambda system like is in your 1983 SC. No need to change anything, although you can do some fiddling to make it run a bit richer at full throttle.

[dannobee]

A couple of bottles of Techron in the tank will clear up the carbon.

Do a leakdown on it and see exactly if there's anything wrong with it.

Did it run good? How was the oil consumption?