Thread: FE BIG BLOCK -- Oil Leak

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427 Shelby Motor- all aluminum recently rebuilt. Since rebuild
have oil leak on right front lower pan, frame rail, and about half way up
( right side) of the timing cover.

The motor is vented as typical in a Cobra - at the rear of the intake manifold
into a vented puke tank. Although, uncertain how to determine if the ventilation
system for this particular motor is adequate?

Thank you.

Originally Posted by virgil

427 Shelby Motor- all aluminum recently rebuilt. Since rebuild
have oil leak on right front lower pan, frame rail, and about half way up
( right side) of the timing cover.

The motor is vented as typical in a Cobra - at the rear of the intake manifold
into a vented puke tank. Although, uncertain how to determine if the ventilation
system for this particular motor is adequate?

Thank you.

First, welcome aboard! You mention a recent rebuild. Have you shown the leaks to the rebuilder or is this a job you did? If you had a shop do the rebuild, take it back and give them a chance to fix it or ask them to give you some ideas of what's going on.

If you did the rebuilt, are you sure you didn't "nick" or cause some local damage to the mating surfaces? And I'm curious if the venting system changed from before?

Lastly, if the rings haven't yet taken a set, they aren't yet sealing the full compression load and "blowby" will be a little heavier than once the engine is "broken in".

Hope it helps.