Smoke and Fouled Plug

[Diogenes]

I've been living with a smoking 390 for a while, but have begun to dig into it more after new developments. I purchased my 66 Galaxie back in 2014 with a smoke issue; I got a good deal on it because of the issue. I got it home and did some research. I put restrictors in the oil passage for the rockers (64 jet), replaced the umbrella seals on the intake valves (my dumbass didn't do the exhaust), and replaced the intake gaskets using ultra black sealant on the gaskets and in place of the end corks. It cleared up most of the smoke for quite a while, but it began to develop again. The plugs always looked good, but recently I pulled plugs after noticing it pretty much constantly smokes out the passenger bank--#3 was oil fouled. I replaced the plug and drove it no more than 10 miles, brought it home and rechecked the plug, it was already oil soaked. Leakdown on the cylinder was about 17-18% and leaking out valve cover filler cap. I didn't do a compression check.

I pulled the intake tonight thinkinking it is sucking oil, but I don't see any clear evidence. Could worn valve guides cause a plug to foul this quickly? Could it be a broken ring with that leakdown result? It didn't seem an excessive leakdown, given what I've read.

I'm not certain how to proceed. Thoughts and opinions please....

[GerryP]

A very worn guide and a sufficient oil supply could lead to a constant smoker.  But the smart money is on it going past the rings.  That leakdown in the high teens isn't all that unusual.  Way too much for a Pro Stock engine, but not outrageous for an old streeter.  The problem with a leakdown is that it's not a great test for diagnosing an oil burner since you could have acceptable leakdown but oil still going past the rings since there's not a direct, sympathetic relationship between the two.

The problem could be a clogged oil control ring and sticky rings, worn oil control ring (and 2nd compression ring), worn bore.  And, back to the valve guides.  Or, anywhere else it could be putting oil into the combustion chamber, like a poorly installed PCV retrofit.

You bought it as a smoker, so maybe it's time to give it some TLC and do an overhaul. 

[turbohunter]

Drainbacks clear I assume?

[My427stang]

I agree with Gerry, but knowing you used a marginal seal on the intake and didn't do the exhaust, you could make a last attempt and use a Viton positively located seal on intake and exhaust.  If you pull one spring off, you can get measurements and places like Alex's Parts and Ebay sell deals cheap enough that it may be worth a shot

One question, when does it smoke, acceleration after decel?  startup?  constant under throttle?

[Diogenes]

Yes, drains are clear and now it smokes pretty much all the time, but more so at start up and deceleration. Its not extreme smoking while idling, but enough to annoy. It smokes quite a bit at high idle after start up. Once it warms up and oil pressure comes down its not as bad. The pcv is dry and not pulling in oil. I've got a set of Comp Cams 514-16 viton seals, which is what I put on the intake side back in 2014. I guess I'll put new seals on and button it back up and hope for the best. I had considered a set of heads that were gone through, figuring bad guides and perhaps excessive milling not allowing intake to seal, but that is just an assumption; no point in throwing money at it without better information. I'm hoping not to need a rebuild, its not something I've got time for right now. I'll give Risolene a try as well, if it ends up being coked up rings for the oil burning. A few people here recommended it.

[machoneman]

This the Rislone you want: https://www.napaonline.com/en/p/NCB100QR?cid=paidsearch_shopping_dcoe_google&gclid=EAIaIQobChMIluGho7_U6AIVr__jBx30-wVBEAQYASABEgKmUPD_BwE

[gdaddy01]

what kind of intake manifold on it ?

[Diogenes]

Edelbrock Performer.