My 390 has been burning a little oil ever since I got the truck in 2012. As soon as the oil gets up to operating temperature, the engine blows out a grey puff every time I start moving from a stop... It doesn't seem to blow smoke once moving regardless of engine or vehicle speed; it doesn't blow smoke if its just sitting there idling either.

Since there are a few different possibilities here, I thought I would do a compression check; although not absolute, I believe the results suggest the issue not being the rings. I checked these by disconnecting the coil, pulling one plug at a time, and having my 8 year old daughter (she got a real kick out of this) crank the engine over for about 5 seconds; I released the pressure and checked each cylinder 2x. Here are the results:

1-118
2-118
3-116
4-119
5-118
6-115
7-115
8-115

- From what I have read these are good numbers since the psi is so close together.

- A few of the plugs were wetter/oilier than I think they would be if it were not getting an excessive amount of oil in the combustion chamber.

The truck was originally equipped with a 360... I personally verified its got the 390 stroke. Coincidentally the block is painted blue where as the heads are bare. I think its likely the block is relatively fresh but only taking the heads off, checking the cross hatching as well as ensuring the top of the cylinder wall isn't flared will completely eliminate any remaining threads of doubt.

When I first got the truck, I replaced the valve cover gaskets since the engine was so oily; it still is and I am pretty certain its actually the front and rear of the intake manifold. When I had the covers off, I believe I noticed it having the old style slip-on valve seals; some of which were not in the greatest condition. I think this is how the oil is getting into the combustion chamber.

Right now, my Plan A is to pull the intake to replace the gasket... While its apart, I figure I can replace the valve seals. This seems to be the most economical approach although I hope messing with the valve springs and such doesn't become too big of a headache. The downside to this is leaving relatively worn heads in service but then again I would end up squeezing a bit more life out of them before a complete overhaul. I would also be re-installing the stock 2bbl intake; eventually I would wind up going through the entire top-end with a 4bbl upgrade. Right now I am really just trying to stop the bleed on a budget. I understand I would wind up eventually re-doing a lot of this. I think I can do all this for about $50 - $60 bucks (costs of the new gaskets & seals) plus my time and it would be good for at least a few years.

Plan B is pretty much to continue to let it drool/burn oil until I am ready to just do the upgrades. It otherwise seems to run fine with lots of power. This truck offers plenty of projects with a few other things taking precedence over all these upgrades.

So while I think I have done sound diagnostics and have thought this through, I was hoping for some feedback or if there is anything else I should consider. Thanks!

 

From your description it definitely could be valve guides and/or seals.

 

I am concerned it could be the guides along with the seals. Only a valve job would take care of this if it is... Definitely potential for them to be worn the heck out. I don't really want to halfway fix so this makes me lean towards holding off; as does reinstalling the busted/heavy 2bbl intake.