UPDATE Intake sucking oil ??

[Timothy B.]

Re: UPDATE Intake sucking oil ??

In my thinking if you mill the flats the side has to be milled also because that angle will change. There is a spec in the how to hot rod small block chevy book that gives the amount to mill off both the flats and sides of the intake manifold if the heads have been cut.

It's something I never paid much attention to in the past but you can bet I will in the future. Al, remember you bought a SWAP meet intake so one never knows it's previous life.

[Ken A.]

Re: UPDATE Intake sucking oil ??

In my thinking if you mill the flats the side has to be milled also because that angle will change. There is a spec in the how to hot rod small block chevy book that gives the amount to mill off both the flats and sides of the intake manifold if the heads have been cut.

It's something I never paid much attention to in the past but you can bet I will in the future. Al, remember you bought a SWAP meet intake so one never knows it's previous life.

If you mill the sides the gap will get bigger, simple geometry........Only cut the bottom.

[Timothy B.]

Re: UPDATE Intake sucking oil ??

If you mill the flats to lower the manifold to the head, the side may also need to be cut so it sits flat (top/bottom) down the sides correct?

I have never done it so you may know better, maybe the side gasket will take that up.

[Timothy B.]

Re: UPDATE Intake sucking oil ??

Ken,

I read in my book the head mating surface of the intake should be milled 125% of the amount taken off the heads and the ends of the intake 175% of the amount taken off the heads.

I would think head gasket selection would matter here also so it may end up just as you say to make sure both are flush with the head area and block area.

[Ken A.]

Re: UPDATE Intake sucking oil ??

Your book differs from GM specs. They have a chart that allows for proper geometry based upon how much the block has been decked. To correct Al's problem I suggest milling the flats.

[Joe L.]

Re: UPDATE Intake sucking oil ??

All------


In my case, I had a brand new GM short block, several brand new manifolds, and, ultimately, brand new GM heads.

[Paul Y.]

Re: UPDATE Intake sucking oil ??

Your book differs from GM specs. They have a chart that allows for proper geometry based upon how much the block has been decked. To correct Al's problem I suggest milling the flats.

Ken, I had the same problem a few years back and I had a machine shop mill the ends or flats of my intake and it solved my problem. I think the heads were milled and nothing was done to the intake. I put it on the block with no gaskets to see where everything sat and the ends held up the intake from touching the heads. I think that I also used thick gaskets and doubled up gaskets etc. and it only kept the problem going. I was glad to finally make it go away. I wish I could remember how much the machine shop cut off but he had a suggestion and we made a decision knowing that if it wasn't enough we could always do more.

[Dick W.]

Re: UPDATE Intake sucking oil ??

Sho' make me wonder how I got by on so many engine that I had the block decked or the heads cut and with the exception of one, never touched the intake or had a problem. The one I knew would be a problem if I did not have thanks cut, .045 off the deck, .020 on the heads

[John H.]

Re: UPDATE Intake sucking oil ??

Your book differs from GM specs. They have a chart that allows for proper geometry based upon how much the block has been decked. To correct Al's problem I suggest milling the flats.

Here's the GM chart for head-vs.-intake machining.


IntakeMachining.jpg

[Timothy B.]

Re: UPDATE Intake sucking oil ??

John,

Your chart shows exactly what's in the how to hot rod small block chevys's book quoted in post #19.

I am not quite sure about this but if you install a thicker head gasket things change again so it may be like Ken say's, mill the bottom to get it to sit flat on both surfaces. The important thing is to check this relationship when any milling is done.