390hp 350 crate using oil

[8door]

Originally Posted by mechanicalman

How many years did it sit? Did you pull the plugs and read them, is it all the cylinders or less? Maybe one, or three seals were not installed correctly or maybe they left them off altogether.

If it's only on start-up that would, IMO, eliminate intake gasket leak (oil sucking into the ports).

Another thing to consider, there was another 290HP SB crate engine before the most recent one, it had centerbolt valve covers. It was a 1 pc seal, a much better engine than the recent one. Which one do you have?

The older version of the 290HP was identical to the 300HP. It had a dish piston shortblock with small chamber Z28/formula 350 style heads, flat tappet cam similar to the later 290 but less intake duration and 112 lobe centers.

It is the later version has the four bolt rim secured valve covers. I had it
about 5 years still plastic wrapped in factory shipping cradle.
I only pulled a few random plugs which are clean ,no oil build up, but I will pull all
there may be one or two seals out or pintched. I think the intake manifold
might be worth redoing as there is a very light blue exhaust mist at idle.

[mechanicalman]

Originally Posted by 8door

It is the later version has the four bolt rim secured valve covers. I had it
about 5 years still plastic wrapped in factory shipping cradle.
I only pulled a few random plugs which are clean ,no oil build up, but I will pull all
there may be one or two seals out or pintched. I think the intake manifold
might be worth redoing as there is a very light blue exhaust mist at idle.

Not saying this if for sure your problem, but I had an 88 formula 350, when I rebuilt it I used fel-pro blue intake gaskets and it started using oil immediately. Those gaskets let oil suck in under vacuum, maybe because of the aluminum intake manifold not sure. Ruined my new cat converter, I think, at least it did fail and I had to replace it when I went through emissions the following year after I had already replaced the intake gaskets.

I put factory GM gaskets on it and the problem was 100% solved.

[8door]

Originally Posted by mechanicalman

Not saying this if for sure your problem, but I had an 88 formula 350, when I rebuilt it I used fel-pro blue intake gaskets and it started using oil immediately. Those gaskets let oil suck in under vacuum, maybe because of the aluminum intake manifold not sure. Ruined my new cat converter, I think, at least it did fail and I had to replace it when I went through emissions the following year after I had already replaced the intake gaskets.

I put factory GM gaskets on it and the problem was 100% solved.

That is the same gaskets I used. Aluminum and steel move differenty as heat
changes .
When I pull the manifold off, I'll look closely for any leak area.
Thanks for the tip.