I have a 396 shortblock with ported LT1 castings that have been milled. I am consuming a lot of oil...2 - 3 litres a week. There is a light coating of oil on the inside of my LT1 intake. My plugs are fine.

I had the exact same problem with my first set up which was heads/cam on a stock shortblock.

Do I need to mill my intake? Is it the PCV?

 

Depends on how much was taken of your heads. If you can provide a number for how much your heads are milled someone could make a suggestion. From what you've said so far, you may need to shave off some material on your intake.

 

Apparently they were only milled 0.010. That alone shouldn't be enough to cause so much oil loss.

The intake bolts did not line up exactly but we were able to get it down good and tight. I think I may be sucking oil through my PCV?

Anyone have this problem?

 

if the bolts lined up poorly, is it possible the heads had been milled before?

 

You know, I never really thought about that. I assumed they were new LT1 casting when they were originally ported and milled, but maybe they were milled before.

I think I will take a little off the intake each time until I get it right. Hopefully it will not cost me too much.

 

Make sure your intake is angle milled. I also had this problem, but was not consuming as much as you. When I reinstalled my new intake I also used rtv around the ports on both the intake and heads. Just a small amount, like a skin pretty much to help the gasket seal so I wasn't sucking oil.

 

I've had the heads on my 5.0 milled several times with at least .010 taken off every time. I never milled the intake and never had a problem. I understand you have a different engine, but I don't think .010 matters.

 

I just had to have .060 off each side of my intake to match the ported Trickflows on my 383. The way we determined it, whas that the bolt holes lined up good without the intake gaskets so we simply removed metal equal to the thickness of the gaskets and now it lines up perfect.

 

You would think .010 would not matter. But my bolt holes do not line up exactly and my engine is eating oil somewhere.

 

I find it hard to believe your bolt holes don't line up with only .010 taken off. Are you sure about the .010? Any chance that more was needed and they just didn't tell you?

 

Maybe the heads were surfaced before like someone stated. Who knows. Best thing to do is to determine where the oil loss is coming from, then go from there.

 

What do you mean by "angle mill". I would imagine the machine shop would just mill .010 or so of each side.

Should I give the shop any special instructions?

 

Jody, I know your heads were not angle milled at TEA or Meaux. The angle of the intake manifold where it mounts to the head might be off or warped.

Bret