Small block chevy smoking problem

[348tripower]

Ok fellas I'm open for suggestions here. I have a 350 +.030 4bolt main 1979 vintage with a pair of truck heads. The heads have been rebuilt along with the motor. It now has 1700 miles on it. It smokes on idle out the left bank. Is using about a quart of oil per 300 miles. I have checked the pcv for proper baffleing. I have checked the trans modulator. I can't get to the bottom of this smoking thing. It does not smoke on start up, but let it sit and run a few minutes and watch the smoke continually come out the pipe. It has a Edelbrock aluminum intake and a 600 edelbrock carb. I pulled the plugs on the left bank and they are a nice light brown. The coolant is full, so it's not water. My brother and my pal Red say it's oil smoke. I can't seem to figure this out, so any suggestions would be greatly appreciated.
Thanks,
Don

[Ohio Blue Tip]

Could be the rings haven't sealed yet?  Broken ring on installation?  Cylinders not honed round?  I would run a compression check or better still a leak down test.  Sounds like definitely a ring sealing problem.

[Dusty]

Don,

I'm thinkin maybe valve guide seals on the left bank...Maybe one didn't get installed right.  Intake manifold gasket on the left side.  Anything causing a leak on the intake side would be worse at idle with full manifold vacume...I had this happen years ago.  One of the heads had been surfaced on the intake side, and it wasn't square with the Manifold surface.....And it was worse at idle...  I hope this gives you some more ammo...

[alchevy]

What color is the smoke? I had white smoke coming out of my '40 Chevy after 12,000 miles. Did the same type things as you mentioned (modulator, checked the spark plugs). I replaced the spark plugs on my 350 and it ran worse at idle. Then found out that I had put different part number of plugs, so went back to AC/Delce 45 (hotter plug than the 42, 45 is what I had before). Inexpensive fix. We also cleaned the carb. I had gotten some bad gas that lead to my problems. I did swap out the transmission also, but the smoke cleared when I got the correct plugs.

See the post: '40 Chevy Update

[rooster]

1 qt of oil every 300 miles is alot!  I think compression test also.

[348tripower]

Dusty,
 After doing a search on the subject I found on Hastings Piston Ring site a statement about intakes. They claim even a minute leak at the bottom side of the intake will cause poor performance and oil will be lost. Also, to everone else posting and reading this post, the smoke starts after the motor is running for a bit. After it gets some heat in it. I would tend to lean towards the intake as it is aluminum will distort with heat more rapidly than the head or the block. Also keep in mind it dosen't smoke on start up. If ya stand there with a cold one in yer hand you can watch start. I wam going to do a leak down test and I will post my results.
Don

Don,

I'm thinkin maybe valve guide seals on the left bank...Maybe one didn't get installed right.  Intake manifold gasket on the left side.  Anything causing a leak on the intake side would be worse at idle with full manifold vacume...I had this happen years ago.  One of the heads had been surfaced on the intake side, and it wasn't square with the Manifold surface.....And it was worse at idle...  I hope this gives you some more ammo...

[1FATGMC]

Don,

I'm thinkin maybe valve guide seals on the left bank...Maybe one didn't get installed right.  Intake manifold gasket on the left side.  Anything causing a leak on the intake side would be worse at idle with full manifold vacume...I had this happen years ago.  One of the heads had been surfaced on the intake side, and it wasn't square with the Manifold surface.....And it was worse at idle...  I hope this gives you some more ammo...

Benny I've had a couple sbc's (got one now) that smokes on start up from bad valve guides, but it goes away pretty quick after the motor runs and doesn't burn much oil.  Since his doesn't smoke on startup I would concentrate more on the intake or rings.

c ya, Sum

[Crosley.In.AZ]

I'd look at the intake as mentioned..

were the heads machined on the block / head gasket surface?  Cut straight?


Cracks in the intake?  New intake?  Old ?

[enjenjo]

you have the rubber end gaskets in there? That is a no no on aluminum intakes, it can cause such a problem with oil in the rear, and coolant in the front

[Dave]

Dusty,
 After doing a search on the subject I found on Hastings Piston Ring site a statement about intakes. They claim even a minute leak at the bottom side of the intake will cause poor performance and oil will be lost. Also, to everone else posting and reading this post, the smoke starts after the motor is running for a bit. After it gets some heat in it. I would tend to lean towards the intake as it is aluminum will distort with heat more rapidly than the head or the block. Also keep in mind it dosen't smoke on start up. If ya stand there with a cold one in yer hand you can watch start. I wam going to do a leak down test and I will post my results.
Don

I think its just junk and maybe a 502 Crate motor is the answer.. Ya id go injection too............ That thing is way slow going down the road or maybe its just your driving style.
Dave

Don,

I'm thinkin maybe valve guide seals on the left bank...Maybe one didn't get installed right.  Intake manifold gasket on the left side.  Anything causing a leak on the intake side would be worse at idle with full manifold vacume...I had this happen years ago.  One of the heads had been surfaced on the intake side, and it wasn't square with the Manifold surface.....And it was worse at idle...  I hope this gives you some more ammo...

[Land Yacht]

Compression test maybe to to isolate a bad cylinder, do all 8. You'd hope to see it on a plug, though. Would it work to pull plug wires with it running, see if the smoke stops with certain cylinders out of the loop.

[348tripower]

I pulled the motor out of the F1 and put in another 355 I had in stock. I started it to break in the cam. It  ran about 15 minutes and developed a knock? I was in the process of trying to locate the problem and she stopped!  :cry: So, I pulled it back out, only to find a rod nut in the bottom of the pan, the rod bolt misssing from the rod and no damage to the crank.   The bolt had gotten wedged between the counter balance on the crank and a wrist pin boss of another piston. So, I took apart the smoking motor, re ringed and bearinged it and put it back in. This baby rattles right from the get go.  :cry: I left for beer.   The next morning {5am} I started pulling plugs. I have em all out except number 7. I pull number seven and find a piece of porcelin missing. I roll this thing over with all the plugs out and I think I still hear something. I put the piston on top and fish with a magnet for parts. Nothing. So I put in seven of the plugs and start it up. It only ran for a mniute or two and I hear something hit the inner fender. So I put the last plug in, fire it up, it runs lake a baby?   Off to the 4th of July parade the next day. Now everything is cool for a week. Saturday I run an errand and park the truk. I look out a few minutes later and see oil under it. I move it back and find trans fluid.  :cry: Yup, you guessed it, out comes the trans. The front pump bushing is loose, pushing against the seal and making it leak. Monday, new bushing, new front pump and tailshaft seal. Tuesday , new torque converter (the first one didn't fit good in the crank) all better now. Thats the story and a really long one.
Don

[Ohio Blue Tip]

If it wasn't for bad luck, you'd have no luck at all!  
Hope it's all well now.

[shine]

i would retork the intake with it up to temp and put some serious hwy miles on it  i've had a lot of smokers that finally stopped. especially crate motors with big carbs washing down the cyclinders. good luck.