Where is my smoke from?

[AMXguy]

I have 700 or 800 miles on my 440 now since a full overhaul with no expense spared and it's burning oil. I get a little smoke at idle and a puff when I start it, no noticable smoke at operation speed, little or no smoke on hard acceleration and no smoke on compression , but a quart will only last about 300 miles. 

 the engine builder who is a very respected race builder says it's from my valve seals and he wants to replace them with viton ones, he says the ones on there now ( positive seals ) have 3 pin holes each and he wanted that to break in the new valves and guides. he told me this would probably happen when I picked it up so it isn't like he just cooked up an excuse when it smoked. but then the machinist who did the work says there is no way that much oil could get past new giudes even if they had no seals, he says it's coming around the intake but wouldn't it smoke on hard compression if that were the case? I do know after when I pulled the intake and put the six pack set up on I could see a little oil in most of the intakes ports on the valve base, and changing the intake didn't change the smoke situation at all so I question the intake as the problem. I also ran it with no PCV to rule that out.

 I would just let him put the new seals on and see if it fixed it but if the machinist is right and that's not the problem I don't want to take a chance on scratching up my fenders if it's going to do no good, if it could be just the seals then I'll help him swap them out but I'd like to be pretty sure that's the problem. any advice?

[71chally416]

I've never heard of "breaking in" valve guides and I've been working on heads for 25 years  There's vacuum in the Intake track and it will definately suck oil by the guides without good seals.

I'd tell him to change the seals and if he screws up your paint job he can repaint the car too. Can't explain why a reputable engine builder would put a motor together "probably knowing" it would smoke. 

[AMXguy]

He says he'd rather change out the seals than stick a valve, maybe he's just over cautious but the guy has a great reputation for trouble free performance builds. if the machinist didn't have a different opinion I wouldn't question him, that's my hang up.  it has the white teflon seals on it now, do you know if those come with pin holes like he says?

 So you are saying it is posible for that much oil to get past new guides if the seals were allowing the oil to them? I remember when we pulled the headers off at the dyno shop there was a film of oil on the exhaust valve stems,  when I pointed it out he said it was the seals don't worry. it's not a real big deal to change them if that's what I need to do I just wanted a second or third opinion.

[Chryco Psycho]

something is wrong , no engine should be smoking after a rebuild if it is done properly , even if the seals are the problem you shouldn`t be using a qt every 300 miles
 I just pulled apart an engine this spring built at very high cost by a "reputable" company , it was using a qt every 100 miles & nothing was done properly internally , they even wrecked the block

[71chally416]

 

If you assemble the heads with the proper valve guide clearance and lube on the guides when they any assembled you shouldn't have any problems "breaking them in".  You're going to go easy on a new motor anyway unless you're some kind of animal, and if that's the case you'll probably screw something else up anyway.

I myself don't care for the teflon type seals unless you really have to use them because of the springs you have. Sometimes that's all that'll fit with triple springs.
I've heard of people PUTTING oiling holes in them because they have a reputation of killing guides because they work TOO good, but I've never seen holes in them the way they come. Why would a seal have holes?? It's just a pain changing all the seals with the motor in the car leaning over the fenders, but knock yerself out if you don't mind doing it. There's probably a better chance of injecting dirt into the motor with the compressed air you  shoot in the cylinders (rust from the air tank, crap from the hose..) to change the seals than sticking a valve, and you introduce all that oil into the combustion chambers and ports and piston tops to gum everything up. 

[Aussie Challenger]

  I put a peformance motor together (aussie hemi 6) and it drank the sump dry in around 200miles, I woundered what i had done wrong as I have built 100's of motors. Checked a little further and found that the motor had very good vac. and sucked passed the PVC, I put a restrictor in the PVC line and stopped the oil consumption, that motor did over 80,000 miles before it started to use a small amount of oil.     I know you said you did something with the PVC.

[AMXguy]

thanks for all the input, I know for sure the oil is coming from the top end because I could see it on top of the intakes when the manifold was off, not just damp but actual oil. I guess I am just going to have to change the seals and if that doesn't do it then I know it is leaking around the intake gasket. I suppose I should restrict the PCV and drive it more before I rule that out 100%, maybe I didn't drive it long enough to clean it out before I decided that wasn't the problem, though with the cam and six pack my vacuum isn't that great anyway so it shouldn't pull as much oil as a stock engine.

[MEK-Dangerfield]

I suppose I should restrict the PCV and drive it more before I rule that out 100%, maybe I didn't drive it long enough to clean it out before I decided that wasn't the problem, though with the cam and six pack my vacuum isn't that great anyway so it shouldn't pull as much oil as a stock engine.

Don't restrict the PCV. That isn't the problem. There is a check-valve in there to prevent this kind of thing.


  Mike

[Robb]

It it smokes on startup, its usually the valve seals.