I am pretty baffled by my current situation with this motor. I have a new 383 that is using oil at the rate of about 1 qt every 100 miles. And it struggles to idle. It is pretty mild with a Lingenfelter 213/219 duration camshaft on a 214 centerline and brand new vortec heads with about 9 to 1 compression, so I am thinking it should idle almost like a stocker.
1. It only pulls about 15 lbs of vacum at idle. I thought perhaps it had an internal intake leak but if I pull the PVC and idle it there is no air being sucked into the valve cover filler. I used a strip of paper by the hole to test it. Yes I have checked everywhere for an external vacum leak and cannot find one.
2. You never see it smoking which is puzzling, you would think it would look like a mosquito fogger using that much oil.
3. After about 1000 miles The plugs were nasty oil fouled and in every cylinder not just one. in addition they were all fouled only on one side of the electrode, the other side looked pretty clean. I figured valve seals or valves loose in the guides so today I replaced the valve seals on one side of the motor but I honestly didnt see anything wrong with the ones I took off so I will be surprised if it makes a difference. The valves did not seem loose in the guides.
4. I have made sure the PVC is working properly, and I see no oil in the PVC hose or the manifold. I am running stock GM valve covers with baffles.
5. Leakdown test only shows about 6% leakdown in the two cylinders I tested, and they were two with the nastiest looking plugs.
6. It has 180lbs of compression dead on after 3 pumps in every cylinder.
Suggestions anyone?
Thanks
Roy

 

Intake gaskets

 

That was one of my original thoughts but every time I have ever seen that it was pretty easy to find the air being sucked in the valve cover filler hole, and that isn't happening, if anything there is blowby coming out of it at idle. Also wouldn't it be more prevalent in one cylinder rather than spread evenly over all of them? It is being fed by a performer air gap, I would think if an intake gasket was leaking that the cylinder where it was broken would be by far the worst. Am I incorrect?

 

is your intake vortec specific?

 

Joe they are the enginequest heads with the standard style intake pattern and the vortec style port and chamber. I portmatched the gasket to both the intake and heads when I put it together and I am pretty particular about assembly. I guess it could be misaligned off the bottom but I would be really surprised if I hadn't noticed that. Although it would be one of the easiest things to fix if it was the problem.

 

I'd say theres a good possibility that the gasket is leaking at the bottom port slightly.
i wonder if theres a simple test?

 

smoke test, and see if it comes out of the valvecover?

 

Hey Joe, I havent ever smoked a cigar, not sure how that would go. LOL

 

LMAO!

i used to live over there in port orange and holly hill about 15-20 years ago. used to be a lot of smokers around there. got any buddies that smoke?