I know.....not a buick....but...my son and I built a SBC 350. Complete build, machine work, boring 30 over blah blah. We broke in the motor on my engine test run stand. Fired up immediately, broke in the cam, no issues. The motor has probably about 3 hours run time on the stand. I noticed that it started to smoke out of the exhaust. The Q-jet I built and was using has major nozzle drip and was just dumping raw fuel into the intake. Swapped it with a known good running Holley. It still smokes.....a lot! Burning oil. At idle not really, but when you hit the throttle it smokes out the entire neighborhood....literally. Pulled all 8 plugs, all 8 were saturated wet with oil. I am sure the rings are not fully seated yet.....but I figured let me start with a leak down test. Ran the psi in each cylinder to 100psi. Cylinder 5 had zero drop. Cylinder 1 and 4 has a 2psi drop. Cylinder 3, 6, and 7 had 1psi drop and finally cylinder 2 had 5psi drop. Feeling these numbers are all good, no? There is just so much oil getting into the cylinders Then decided a compression test. Cylinder 3, 4, 5, 6, 7, and 8 came in consistent at 170psi. Cylinder 1 was 180psi and lastly cylinder 2 was low at 150psi. Perhaps the rings are still seating? What should I look for? Cylinder 7 and 8 without the spark plugs just keep leaking out out of the spark plug hole, I don't get it? not sure where it is coming from?? I would think if the head gasket or rings were bad, the leak down would have showed. How is all this oil getting into the cylinders? Any guidance would help. I really don't feel like pulling the heads. I did pull the intake to fix a real leaks at the end rail, all looks good inside the intake. Chevy motors suppose to have a oil baffle like our buicks? Any direction or help would be appreciated! Jay
Possibly valve seals stuck to the valve stems? I don't think I have ever had a fresh one smoke like that.
hmm....valve seals. That I will check. One other question. With the intake off, I noticed that 17 lifters remain pumped up hard. One, I can easily depress. Should It be replaced? Or they pump up one it runs again?
Without a load, you cannot get the rings to seat correctly just varying the RPM. You need to put resistance to get the toque for the pistons to work against, and that results in cylinder pressure against the rings and allows them to "knock the sharp peaks" of the hatching on cylinder walls. You cannot get that on a stand (unless it's on a dyno, or you have a disc/drum brake on the back of the transmission. Most unlikely.) Your numbers are not bad, and the oiling., smoke and plugs, along with some leak down, is normal until you seat the rings. Running the engine without doing that, it is possible to get some glazing/varnishing from the oil and lessen good seating later. How long before you can get it the car and on the road? Getting the car warmed up and about 10 miles, then half dozen pulls, like getting on the freeway or passing on a two lane, 20-80 MPH, WOT) and keeping an ear out for pinging, should do it.
Thanks Michael.....I'll bet you are spot on. We built the motor as a father son project. It still sits on the stand. The goal........was to yank the 305 in his 87 Camaro and swap this 350 in. But that 305 just runs so darn good (it's a carb 305 we yanked the computer and fuel injection) so not really sure how long it will sit. We just like to run it and rev it lol. The particular heads, have new factory springs with the inner damper spring, so I do not believe they would use the umbrella type seals, only the little oring seals. Just boggles me, that when I remove the plugs, the oil just dribbles out.
I think Mr.. TrunkMonkey nailed it. I didn't think about the motor not having a load to seat the rings properly...
I agree with trunkmonkey. Needs a load to pressurize the cylinders to push the rings out against the cylinder walls.Plus add to that if you’re breaking in with synthetic oil.
Yes, all that is correct, but mostly that relates to cylinder sealing compression and firing pulses...oil rings are a bit of a different thing... They should be scraping nearly all the oil off the cylinder. the steel rails really don't break in like the thicker cast/ductile Iron compression rings do. What is really happening with the iron rings is they are wearing into more complete contact with the cylinder wall, whereas the steel expander rails already will conform well to the cylinder, and any irregularities or out of round that exists. If an engine I built and put on the run stand was smoking and spitting oil out the spark plug hole, I would be looking for issues. There is a way you can tell.. where the oil is coming from.. get a bore scope.. look in the plug hole at the piston top.. if it has carbon on it, but a shiny ring around the very outside, then oil is passing thru that ring set. Might be too new to see this evidence though.. Make sure the valve covers are baffled where the pcv valve is located. Look for oil in the hose if you suspect an issue there. Take the bore scope and look down the intake manifold, to see if you can see how wet it is. Although if it has a decent size cam in it, then it will be normal for oil coming up past the rings to make the intake tract wet.. JW
Different rings require different cylinder finishes. Did you follow the mfg recommended procedure and finish for the rings used? I'm no expert, just a hack that puts junk together on the cheap. But if I had a skeeter fogger like that I'd be looking to do something different . Let us know how this progresses. I'm always up for learning.
I've seen a mismatch between between a high volume oil pump and composite intake gaskets causing a massive oil burn. Same symptoms you have, a ridiculous amount of oil smoke. Upon tear down the intake gaskets were saturated with oil. We figured the HV oil pump was over oiling the top end and was splashing everywhere. An oil pump swap cured it. This was on a sbc 400.
I wonder if it was more the gasket material than the pump. The only reason that I say that is because on my BBB, the timing cover was leaking like a sieve and when I removed the cover, the gasket was soaked and falling apart after 1000 miles. I had used a Mahle gasket. I replaced it with a Fel Pro gasket and it no longer leaks. Just curious.
I think they were the felpro gaskets with that are grey/black with the raised blue lines. They looked as if they were dipped in oil halfway up. The oil pressure was out of hand. It would idle hot at over 40 psi. Any blip of the throttle was 80 plus. I don't remember if we put the same gaskets back in, but i do remember we only swapped the pump and reinstalled. No more smoke and it eventually went in the 11s.
Thanks everyone. I have the intake off already. I probably have a total of 2 hours run time. I used the bore scope and all piston tops shine like brand new. No staining. Leak down test was great. I did verify that the valve stems do have good seals. The intake runners were saturated with wet gas from the q jet. I did have a hacked pcv set up with hacked valve cover baffles due to crappy valve covers. I now have better covers with real baffles. I am used to Buicks with valley pans. The sbc does not so i run the pcv to the carb. Cam and lifter look great. Cylinder walls look nice from bore scope. Gonna reinstall intake and see whats up. It was just so much smoke ha! Wife was closing all window in the house. Is there a way to simulate load on the test stand?
If you can figure out how to put 1.5-2 tons of weight with the division of mass to simulate a 1/4 to 1/3 of said weight/mass, against the crankshaft with stuff you have lying around your garage and not get yourself wrapped up in a furball doing it (please, video the attempt), then no, I cannot think of a way to do it. But with enough beers, and friends and too much time on the weekend, anything is doable. Once....
Perhaps i have found my issue. Could poor pcv really cause such havoc?? I had these aluminum valve covers on where first, there were no baffles and the opening was directly above a rocker arm. I have since put on better covers with real baffles and the baffles are placed in between the cylinders. Have not ran the motor again since all testing and having to fix leaking intake end rail. Anyhow.... I tested 2 qjets that I personally rebuilt and a holley. Just now I was wiping each down to reinstall. So instead of raw fuel draining out of the bowl etc, it wasl ike yellowed oil. Sticky oil filled all 3 carbs. Is it possible that bad pcv caused TONS of oil sucked into the carb and then obviously burned it and fouled the plugs?
Oh, yeah. Was doing a nice long hard pull on mine shortly after break-in (and well after rings were seated) and up around 95 MPH I saw massive blue smoke screen instantly, like a Thunderbird Solo, "Smoke On!". (Thought maybe I lost rings ) Let off the throttle, and the smoke stopped about 3 seconds later, I got down to 70 MPH, no smoke oil pressure good, temp good, no noise so I eased into it, no pinging, got power. WOT started pulling and hit 95 MPH and "Smoke on!" Thought, "this could be fun in certain situations", then drove on back home, checked modulator, no oil in the line, no oil leaks, so I figured PCV sucking oil that is likely either whipping to a froth at higher RPM for long period or ring blow by. Did compression test (warm and cold) and had 175 PSI on all holes. Easy test was to pull the PCV from rear of intake, plug that hole and put the valve in the valve cover where the breather was. Borrowed (swiped) the Nailhead's twist on breather and stuck it where the oil cap is, and put the PCV in the back of the valve cover, took it back out and went WOT to 110 MPH and no more low level airshow. I have roller lifters, composite intake gaskets and used the small TA Performance lifter splash shield (thier pic below), but not the valley shield, but since it does not do it with the PCV relocated, I am not worried about "why".
Well....update. All is good with the 350 chebby. It totally ended up being the pcv system. I swapped different set of valve covers, that has the correct baffles and placed in between the cylinders and not directly above a rocker. runs nice and clean, no smoke. Thanks for all the valuable input! Thank goodness I am no longer smoking out the entire neighborhood! Now...to figure out what to put this in https://youtube.com/shorts/kqX6LTHOYrA?feature=share https://youtube.com/shorts/FYI3Zpge6TM?feature=share
