911 Blow by

[jmpearson]

Good Morning. Just finished an upper end rebuild on my '75-911s. Upon starting, the idle surges and the exhaust emits whitish smoke . Sometime the smoke goes away not to return until the next startup. Other times the smoke stays for 5-10 minutes. the bottom end looked good with the original cross hatching in the cylinders intact and not worn down. Also, the vent in the air cleaner does not show excessive blow-by. The bearings were replaced and the case was line bored. Cam gear was replaced.

The car runs very strong except for these issues. Any ideas. such as 02 sensor, heat temp sensor or idle control valve? Fuel regulator and fuel distributor were both replaced. pressure regulator springs were replaced although spring sizes were different than the stock parts. Could the big oil tank on the right be draining back into the motor and overfilling it?

H E L P!

[Reiver]

New rings?

[timmy2]

Search "Italian tune up"
Fairly normal for the white smoke when freshly rebuilt.


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[dfhtrhjn]

Your new rings need time to seat in the cylinder. My top end rebuild took about 400 miles of gentle driving (less than 4k RPM). It happens to every new ring+cylinder combo. If you aligned the ring gaps incorrectly then the smoke never goes away and you have to pull the cylinders.

[zippy_gg]

Originally Posted by jmpearson

Could the big oil tank on the right be draining back into the motor and overfilling it?

H E L P!

So... how much oil did you put in the engine?