intake manifold leak
Thread Starter
Racer
Joined: Feb 2009
Posts: 265
Likes: 0
intake manifold leak
Got the 427 sb running, but the gasket between the intake and heads seems to be leaking a little again. In the middle, both sides, by the 2 middle intake bolts. Oil (don't see how it could be coolant) seems to be wicking/seeping past the gasket. Even used sealer on the gasket this time when I built the engine. Tried everything to get a torque wrench on the middle bolts- doesn't look possible. I tighten them with the 3/8" wrench and even put a cheater bar on the wrench. Saw a little oil get squeezed out like it went tighter, but I think it's still doing it on one side- afraid to go tighter without stripping the bolt out.
Thought about trying to seal it with gasket maker on the outside. Had the problem on the old 350 with the same intake and heads- all were new parts to start and shouldn't be off. Machine shop redid it once on the old engine, but the problem didn't go away. Trying to get the new engine perfect. Thanks
Thought about trying to seal it with gasket maker on the outside. Had the problem on the old 350 with the same intake and heads- all were new parts to start and shouldn't be off. Machine shop redid it once on the old engine, but the problem didn't go away. Trying to get the new engine perfect. Thanks
Drifting
Joined: Nov 2003
Posts: 1,874
Likes: 7
From: l In
What heads and intake are you using ?
Mr. Gasket makes a thicker gasket that might help. If you are using overseas parts that could be your problem. I just removed a set of Pro Comp alum heads and a crosswind intake to eliminate a similar problem.
Mr. Gasket makes a thicker gasket that might help. If you are using overseas parts that could be your problem. I just removed a set of Pro Comp alum heads and a crosswind intake to eliminate a similar problem.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,113
From: Crossville TN
Chances are that your heads have been re-machined a bit to flatten up the cylinder head face. When that is done, the heads sit just a bit lower and the intake manifold 'spread' distance becomes enlarged. That makes it difficult for the intake to properly mesh with the heads and can leave leak paths at the gasket faces. Remove the intake and the intake-to-cylinder head gaskets. Then, place the intake back on the block/heads and use feeler stock to measure the gap where the gaskets will go. That will tell you what thickness gasket you need to properly seal your intake. The gaskets should be .020" [or so] thicker than the largest gap measured during that process. If the gaskets are too thick, then the other intake seals will begin to leak.
Last edited by 7T1vette; Mar 31, 2009 at 10:00 AM.
Thread Starter
Racer
Joined: Feb 2009
Posts: 265
Likes: 0
Heads are Brodix 8Pro and a Performer RPM intake.
Thread Starter
Racer
Joined: Feb 2009
Posts: 265
Likes: 0
Chances are that your heads have been re-machined a bit to flatten up the cylinder head face. When that is done, the heads sit just a bit lower and the intake manifold 'spread' distance becomes enlarged. That makes it difficult for the intake to properly mesh with the heads and can leave leak paths at the gasket faces. Remove the intake and the intake-to-cylinder head gaskets. Then, place the intake back on the block/heads and use feeler stock to measure the gap where the gaskets will go. That will tell you what thickness gasket you need to properly seal your intake. The gaskets should be .020" [or so] thicker than the largest gap measured during that process. If the gaskets are too thick, then the other intake seals will begin to leak.
