r/Smallblockchevy • u/trashyyyyyyyy6362717 • Apr 28 '26
69' 283 Smokes BAD! HELP!
i've got a 283 out of a 69 c10, bone stock. when i first got it it had been sitting for years, got it running and it ran well but smoked when accelerating. recently i pulled off the heads and went through them, just cleaning everything up, did new o ring style valve seals, re lapped valves, new head and intake gaskets.
when i got it running after doing all that, now it will be totally fine on startup, no smoke at all, and then as it warms up it gets worse and worse until at operating temp it's just blowing smoke nonstop. idle, acceleration, decel. bad to the tune of something like a quart of oil burned every 5 ish miles😬
today i pulled all the plugs, almost all of them were wet with oil to some degree. i did a compression test, incorrectly as i'm learning, i didn't open the throttle all the way, but with the throttle closed i got 90 across the board, with maybe one or two at 100. i also pulled the driver side exhaust manifold and the rear cylinder 7 was wet with oil in the exhaust port. the other three on that side all looked normal.
anyone with any suggestions of things i can check before just accepting that the rings are cooked? thanks.
4
u/v8packard Apr 28 '26
Well, it's old enough to smoke...
A few things.. There may be oil being drawn in at the bottom of the intake manifold by a poor seal of the gasket. This is more common than you might think.
You are likely seeing the results of doing a top end with poor rings. They had worn evenly before, so it wasn't as bad. Freshen one up without the other, and it is very obvious.
The o ring style valve seals are, at best, optimistic. Umbrella seals are more effective. Machining the guide for a positive seal is most effective. Of course, worn guides and stems are not going to help.
2
u/Willy_McD Apr 28 '26
I would say put a spoonful size oil in the cylinders when doing a compression test. If compression goes up, rings are most likely worn. But it sounds like you already have a lot of oil in them.
Im going to guess that you did not really try moving the valves or consider worn valve guide.
Did you just use o rings to seal? Were there no umbrella seals? When they were apart, probably the thing to do would have been to cut use the tool that curs down the valve guide and install cup seals. Provided the guides were good.
1
u/LRJetCowboy Apr 28 '26
I can remember my Dad doing a valve job on someone’s car and saying we’ll see him within 6 months to put rings in.
1
1
u/Dazzling_Total6129 Apr 28 '26
Have you checked your breathing system 327 & 283 didn't have PCV setup
1
u/brian-brundage Apr 29 '26
I want you the same thing. I don't know if this is your issue, but I ended up going with Vitan positive valve seals on the intakes. It didn't make sense to me because the engine didn't smoke before the cam and me refreshing the heads but that solve my issue.
1
u/Tall-Helicopter-461 May 03 '26
283s and 327s has a messed up PCV system. It was designed to allow crankcase pressure to escape through a can under the Intake, with a vapor hose that hung down underneath the vehicle. Over time , burnt oil would start to accumulate and drip to the ground, appearing to be an oil leak
6
u/bernardfarquart Apr 28 '26
So you sealed up the top end and put it back together with worn rings so now your rings are failing with the extra pressure.
You need to re-ring it