The engine is a 406 small block, 750 CFM Holley vacuum secondary carb with Supercomp hooker headers, 3inch dual exhaust with an H pipe, in an 84 corvette.

Anyway the thing is, the passanger side exhaust outlet is considerably dumping more blue smoke then the right side and its not a whole lot of blue smoke, but in park it is really really noticable.

I also did a compression check on the cylinders and heres what I came up with:

Passanger side:
2 = 180PSI, 4 = 173PSI, 6 = 175PSI, 8 = 177PSI
Drivers side:
1 = 180PSI, 3 = 185PSI, 5 = 185PSI, 7 = 180PSI

Plus some other info, the engine was rebuilt last about 9 months ago and I have about 5000miles on it total. Then I swapped the heads for some ported Sportsman 2 heads and only have about 50 miles on them.
Could it be a leak on the cylinder gasket? Please help me out, the car pulls really hard at about 35mph and at 1/2 throttle it basically pins me into the seat. Other then that I have just been cruising in it since the new heads and not really hammering it.

 

Don't know the cam spec, but the PSI are all equal for the cyls.......could be a gasket or valve seals. What valve seals are in it?
Guide material?
How much oil is it burning off the dipstick

 

There is no pressurized oil at the head gasket. There are really only two ways for oil to enter the cylinder. Past the rings and past the guides. Your compression test shows that the compression rings and the valve seal is great. The oil rings could be at fault as well as the valve guides and/or valve stem seals. A third possibility. If your PCV isn't baffled inside of the valve cover, manifold vacuum can suck oil into the intake.

RACE ON!!!

PS. I just thought of a 4th way. A poor intake to head gasket seal could suck oil from the valley.

 

Oh man thats alot of ways the oil can get into the combustion chamber.
How can I find out where the oil is coming from without taking the heads off the engine? Im just throwing out some ideas, but If I pressurize the intake manifold, would I be able to find a leak? Or hear it somehow?

I'll have to run the engine for a little bit maybe 10mins or so and then see how much oil the engine ate from the 10mins. ANyway thanks for the info.

 

Another way oil can be sucked into the chamber, although much slower, is past the rocker arm studs if they aren't sealed well.

 

check and improve the little things first , are the plugs reading alot
different from side to side

 

That is 4 ways, plus the rocker arm studs. Not all heads have the stud hole drilled through to the intake port. A good assembler should have sealed the studs in through drilled heads. A little logic and history can help here. First, I would suspect the oil rings, last. Next is the heads. Were they fresh? Were the guides and seals attended to? The PCV is a simple test. Just disconnect it and see if the problem continues. None of the afore mentioned conditions "automatically" attack only one bank. An intake manifold gasket, easily can.

If *I* were trouble shooting this problem, the first thing I would do is eliminate the PCV as the cause, by disconnecting it. I really don't think this is the problem, because it should affect both banks equally. But the test is painless. Next, I would pull the intake, because that is the most likely cause for smoke from a single bank. Look for a sign of a lack of sealing, especially in the lower 1/4 of the ports. Also look for signs of oil migrating past the gasket. Due to other machine work the angle between the manifold and the head, may be off. The manifold may sit too high in the valley between the heads. Or may be that it simply need to be more carefully assembled. Good luck, and...

RACE ON!!!

 

I know this is a stupid question, but where is the Positive Crankcase ventilation at?

I really think it might be the intake not align'd correctly b/c with the old heads it never had this problem.

 

The positive crankcase ventilation, valve, was in the front of the drivers side valve cover, on your Crossfire. Are you using the old valve covers and retaining the original hoses?

RACE ON!!!

 

Oh yeah, then I did try it, it doesnt help the engine still burns oil. Im using different Valve covers but I still have the old lines hooked up hopefully where they need to be.

I think I'll just have to pull the manifold and see if the oil is going into the intake.

 

Today I started to take off the intake manifold bolts after moving everything else out of the way. When I started taking off the bolts from the passanger bank, which is the one that has more blue smoke out the tail pipes, the bolts where a little loose. The ones that gave a slight drag throughout the entire bolt where clean, the others had oil deposits on it. Same on the drivers side aswell.

Then when I removed the valve covers, I shot some light down the intake runners, and sure enough theirs about a tablespoon of oil ontop of each valve, some a little less then a tablespoon size some a little more. Afterwards I inspected the intake manifold and the flange that mounts to the heads was slick, it had oil residure over it, plus the intake gaskets has slight deposits of oil inbetween the two sets of runners, very small amount though.

So now Im thinking that the oil pressure is probably pushing the oil through the gasket and the head/intake and is getting sucked into the intake runners. How can I fix this? If I could, how can I make sure the cylinder heads are straight and true without taking them off the engine? Or when I install the manifold over again, would I have to retorque the intake manifold after 20-30mins of run time or something? Use Or do I have to use something on the intake bolts before I put them in to snug down the intake manifold?

Thanks CFI-EFI for all the help.

 

The same as between the heads and the block, there is no pressurized oil between the heads and intake manifold. Oil can enter the intake runners because of a gasket leak, which is a vacuum leak, between the heads and intake. The leaking vacuum sucks the available drain back oil in the valley into the ports. This can be aggravated by high crankcase pressure caused by blow by and/or a defective PCV system. The flatness and straightness of the manifold flange of the heads can be checked with a straightedge while on the engine. Be thorough. Check every possible way you can think of. Across the bottom of the ports, across the middle, and again the tops. Also check diagonally, both ways. Do the same with the intake manifold. All gasket surfaces have to be absolutely clean of ALL old gasket material, and dry of any oil residue. IF all the surfaces are flat and straight, dry fit the manifold without gaskets, to check for any differences in the clearances, especially, top to bottom. Dry fit again with the gaskets. recheck everything again. And this time, look at the bolt hole alignment. Since the manifold is the newest item in the equation, you should dry fit the old manifold both with and without gaskets, for comparison purposes.
With the block, heads, and manifold all coming from different engines, you have no way of knowing what has been, decked, milled, or angle cut, to match what. My guess, is that the intake may have to be surfaced, but a good conscientious sealing job, and a careful installation may cure the problem. *I* have never applied any sealant to intake manifold bolts, but if it is a concern, I'd use Permatex No. 2.

RACE ON!!!

 

Several years ago I got some sportsman 2 heads and forgot to seal the intake rocker studs and had a similar problem. Also if the heads had been sitting for any time and you didn't lube up the seals real well that could also be a problem. If it has vacuum at idle that is lower than before that would also be an indicator of a leak. Mine ran real good under throttle also.
bob