Burning excessive oil!! Need advice.

[76-77-78]

So let’s start with the engine specs. It’s a 383 stroker bored 040 with roughly 10,000 miles on it. The cam is a lunati with .443/.465 lift. it has an edelbrock EPS manifold, edelbrock 1406 carb, on top of it. It has dart iron eagle heads, with 72cc combustion chambers. It has headers with true dual exhaust. Now to explain what’s going on. The engine has always used some oil, but about 1500 miles ago is when I swapped heads. I swapped from gm 882 heads, to the dart heads. The power difference between the two is night and day. But ever since the swap I have been burning a quart every 100 miles. Which is expensive, and it fouls my plugs rather quickly. So I did what any wise mechanic would do and went and googled it, Lol. Any ways, I learned of a couple options to look into. Which were an oil leak at the bottom of the intake gasket, and a leak past the threads of the rocker studs. So I went to work on the truck and I pulled the intake, and I can’t really find any signs of a leak at the bottom of the manifold. So I pulled a valve cover, pulled the rocker off, and the stud out, but my heads aren’t bossed all the way into the intake or exhaust port so that can’t be it either. There is a bit of oil and soot build up on top of the intake valves though. So anyways I’m pretty stumped, and could use a little help. Oh and also I assembled the heads myself. They have z28 springs, new Elgin valves, and umbrella seals. If you guys have any ideas I’d sure like to hear them.

 

[Bextreme04]

That's a LOT of oil to be burning up in a pretty fresh build. Have you run a compression test? Sometimes the edelbrock manifolds have been known to warp a bit and have really bad sealing. You would need to have a really big intake leak to have that much burning, and it would probably run like garbage from the vacuum leak if that were the case. Are you running a PCV system?

 

[Bextreme04]

How many plugs are getting fouled?

 

[76-77-78]

Yes I am running a PCV system on stock gm baffled valve covers. And the plugs that are getting fouled are 5-7 on drivers side and 2-4 on passenger side. The other 4 plugs have a darker color to them, but definitely are not fouled.

 

[76-77-78]

I will get a compression test done as soon as possible here. and I’ll try and upload pictures of the plugs too.

 

[QBuff02]

Couple of different things to look at. Did the head specs say that you could use umbrella seals? Some are cut for umbrella seals and some are cut for positive lock/viton type seals. A quick and dirty way to rule out the seals is do you notice any blue smoke upon deceleration? This is a sure fire way to pinpoint if it is valve seals/guides or not. When you pulled the intake off, did you notice any oil in any of the intake ports? Or oil residue in the ports? Because as you googled and found out, it very possibly could be leaking past the gaskets and drawing oil into the ports, or the intake could be warped or mismatched to the head mating surfaces. Which could require having the intake milled so the clamping force is equal across the gasket. What oil do you use? And it's very possible that if you use a synthetic and switched to it before the rings fully sealed, you could be blowing oil right by the rings and burning it up as part of the combustion process. I am not a fan of synthetic oil in our old dinosaur engines, especially ones of any performance variety. If the oil past the rings is the case, which is entirely possible, i'd say you probably never had the rings fully seated, and strictly speculating that you went from a bigger chamber/lower compression cylinder head to a smaller chamber/higher compression set, you now have more cylinder pressure thanks to the bump in compression ratio making the problem even worse. What rod/piston combo are you running? I've seen guys run a "383" with 6" rods and it only puts the wristpin that much farther into the oil rings due to the shorter piston height compounding an already problematic area. One other area to check is the pcv system and to make sure it is plumbed and operating correctly. But back to that comment you made about the oil and soot build up on top of the intake valves.. That leads me right back to valve seals or an issue with the guides or valves themselves or a combination of the before mentioned. When you decelerate, or close the throttle or however you want to call it, the engine is in a high vacuum state, which is exactly when the engine draw will suck the oil right past the valve seals through the guides into the intake ports to the cylinder and burn it off and/or foul plugs.

 

[76-77-78]

Ok so the short block is a 010 70s gm block, and the rotating assembly is an eagle specialty products stroker kit. that came with pistons, piston rings, 5.7 rods, crankshaft, balancer, and flexplate.

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These are the compression numbers dry and cold. But something must be wrong for split numbers like that.

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these are the plugs. I know they aren’t great pictures but it’s the best my camera would do.

 

[76-77-78]

Oh also I never did notice any smoke at any time. Which seems strange considering how much oil is being burnt up. And I’ve been keeping a close eye on it recently. Also the cylinders with the highest compression, are the ones with the worst looking plugs

 

[75Monza]

Don't mind my simple questions, first when you check compression, do you have the choke open and the throttle wide open?
Next thing is you said that 5,7, 2 and 4 get fouled the worst...noticed that at least 5,7 and 2 are the higher compression cylinders.
Next, did you or someone else fit the rings to the cylinders...wondering what they were gapped to, loose or tight?
Also, just noticed your carb. Could just be my opinion, but I've had the 1406's cause no end of crap just like this for fouling plugs on an engine that didn't foul with a quadrajet. Never did get to the bottom of why, but when I tore motor down I did have slight leakage past past the valve stem o rings, no umbrellas on a set of summit 2.02's.

 

[76-77-78]

The rings were all gapped by myself to .017-019 in accordance with the manufacturer’s specs. Not saying I didn’t manage to miss something, or put one in upside down or something.

and when the engine was broke in I was using a qjet carb, with stock cast manifold. I switched to the EPS at around 4000 miles I think. As far as the 1406 carb goes, I’ve been thinking of switching back to the qjet and I might still. But the 1406 seems to be running just fine, just not quite as good of gas mileage.

 

[DoubleDingo]

My thought is valve seals, or rings. If it were leaking oil, I'd suspect valve covers, the back of the intake at the china wall, no gasket on the distributor, or possibly the oil sending unit.

 

[76-77-78]

There are no oil leaks to the outside of the engine. The more I dig in the more I’m thinking it’s a combination of rings and valve seals.

 

[75Monza]

Just curious again, what happens when you add oil to a cylinder after taking a compression check then check it again? If it's rings, the number should go up from what I've observed before.

 

[76-77-78]

I will probably check into that tomorrow. It’s dark now and getting kinda chilly out. I think I might just have to put it together, and try and hold out till spring. Or till I win the lottery, and can build a huge heated shop, so I don’t have to work on a cold open sloped driveway. Lol

 

[Ricko1966]

Are these new pistons? Did you install top ring with the bevel up and secondcring with the bevel down.A trick for working outside in the cold throw a tarp over the car and put a forced air kerosene heater behind the car blowing under, you will be in a constant warm draft. I changed a 2 piece rear seal in 10 below weather this way.