Thread: Recent FE390 rebuild. Getting blow back smoke out of exhaust and engine. Pleas help

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What oil are you running?

Some folk claim that synthetic doesn't allow rings to seat, and break in should be done with dino oil.

There has also been a lot of discussion on this board regarding zinc for the cam break-in. (Just search the threads for zinc, you'll find it - if you're interested)

Ford FE's are infamous for leaking oil into the intake ports if the intake is not installed correctly or if the mating surfaces are not machined to mate exactly. This is also an issue if Print - O - Seal intake gaskets are used. It can also happen if the cork china wall gaskets are used, which can result in the intake standing proud of the head mating surface and not sealing correctly.

If it doesn't clear up, you might want to consider removing the intake manifold, and cleaning all gasket surfaces on the head, intake and block perfectly. Use a feeler gauge with the intake sitting on the engine with no gaskets to check that all surfaces are parallel and true. Then reinstall using good solid intake gaskets, and using "The Right Stuff" on the ends for the block china wall seal.

As you know this is not a easy job due to the FE's unique architecture with the intake actually making up half of what is traditionally the cylinder head, and subsequently the pushrods passing through the intake. It's not terribly difficult, though. Just take your time, then re-adjust your valves when done. Best of luck.

Originally Posted by DennyW

Do you have an automatic trans ? It could also be the vacuum modulator allowing trans fluid to enter the vacuum line.

As Denny says above, remove and plug the vacuum line from the carb that is going to the automatic tranny and see if the problem disappears.