390hp 350 crate using oil

[8door]

This is a general inquiry about a new engine using oil.
I bought the new crate engine from a GM dealer several years ago and stored
it pending rebuilding my 68 C10. A year ago finally got it ( the truck)
put back together and installed the 350 with a Holley and an Edlbrook intake
stock dual pipe exhaust and fired by MDS electrics.
Did the breakin at 2000 rpm for 1/2 hour drained out the Lucus breakin oil
filled up with regular Valvoline 10-30 and hit the road. Runs great nice smooth power
through out easy rpm watching oil pressure and temps.
After about 100 miles stated driving at higher speeds, checked the oil level uhmmm down 1/2 quart so now that seems to be it's thing, 100 miles add 1/2 qt
Plugs are clean, but noticed blue smoke at restarts while engine is warm.
My first suspect is Valves ???? As of today I only have run it about 1800 miles.
I have read several other forums and comments that GM valve stem seals are a problem.
Any body else experienced this with new crates ?????

[Longhorn 70]

Valve stem seals dried out from sitting?.....

[mechanicalman]

Originally Posted by 8door

This is a general inquiry about a new engine using oil.
I bought the new crate engine from a GM dealer several years ago and stored
it pending rebuilding my 68 C10. A year ago finally got it ( the truck)
put back together and installed the 350 with a Holley and an Edlbrook intake
stock dual pipe exhaust and fired by MDS electrics.
Did the breakin at 2000 rpm for 1/2 hour drained out the Lucus breakin oil
filled up with regular Valvoline 10-30 and hit the road. Runs great nice smooth power
through out easy rpm watching oil pressure and temps.
After about 100 miles stated driving at higher speeds, checked the oil level uhmmm down 1/2 quart so now that seems to be it's thing, 100 miles add 1/2 qt
Plugs are clean, but noticed blue smoke at restarts while engine is warm.
My first suspect is Valves ???? As of today I only have run it about 1800 miles.
I have read several other forums and comments that GM valve stem seals are a problem.
Any body else experienced this with new crates ?????

No, but never knew anyone who let it sit that long; I agree valve stem seals likely the problem.

If that's a 350-290HP these are valve-seals listed on this link from GM. Not sure how old the crate engine is if the parts match.

10212810 8 Seal, Int Vlv Stem Oil
12564852 8 Seal, Exh Vlv Stem Oil
http://www.chevrolet.com/content/dam...e-12499529.pdf

You might try some "high miler" oil, it has seal softener in it. I put in in my 350-330HP and it stopped the oil cooler hose leak.

[8door]

It is the 290hp 350 I typed it incorrectly on original posting.
I'm going to talk with GM folks and see if there is a record of failed seals.
I can't believe the seal would be dried on a brand new engine.

[mechanicalman]

Originally Posted by 8door

It is the 290hp 350 I typed it incorrectly on original posting.
I'm going to talk with GM folks and see if there is a record of failed seals.
I can't believe the seal would be dried on a brand new engine.

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.

[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.

[hamjet]

Check to see if your pcv is working correctly also...

[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.