Intake/Exhaust Manifold lug thickness

TommyCoupe

TommyCoupe

Senior Member
I just bought a new Exhaust manifold and am ready to install it. Because the intake and exhaust manifold share the same studs/nuts, I expected that the thickness of the lugs on both parts would be the same.

If I measure the thicknesses of both, the intake is (at worst case) .012 thinner than the exhaust manifold.

Is .012 "close enough" or can it be shimmed on the nut side to make up for the offset ?

Tommy-
 
the cup shaped special washers go under the nuts and against the mainfolds. the washers will make up for that distance... put the washer on with the dome facing the nut

since you only purchased one new manifold make sure you get them surfaced
 
Mitch, don't you mean the curved side faces the manifold lugs? That is the way the Snyders drawing shows it that came with my exhaust manifold.

I used my old intake but it had rust build up on the flat mating surface that goes against the exhaust manifold. Be sure all that is cleaned off. I wire brushed it, then carefully flat filed the bumps off.

THEN you make sure the surfaces that face the block are in the same plane...and if not then bolt them together and get them faced off at a machine shop as a unit.

This time BTW, I used the two individual gaskets rather than the long one piece gasket and it seems to be working pretty well.

JackD
 
This is what Snyder's shows: (I think you are both saying the same thing, just using different words.)
 

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Seems to me that if the surfaces on both manifolds are flat and smooth on the side that matches up to block, and you torqued the manifolds down using the cupped washers and nuts, that they would seal tightly against the block. Then bolt the 2 manifolds together.

Does that make sense, or am I missing something ?

Tommy-
 
TommyCoupe said:
Seems to me that if the surfaces on both manifolds are flat and smooth on the side that matches up to block, and you torqued the manifolds down using the cupped washers and nuts, that they would seal tightly against the block. Then bolt the 2 manifolds together.

Does that make sense, or am I missing something ?

Tommy-
Click to expand...

Sounds good as long as the manifolds fit nice where the 2 bolts clamp them together.
 
Judgement on the tightness, but check for a few heat cycles to snug the nuts down.
You are correct that the last bolts tightened are the 2 that bolt the 2 manifolds together.
Careful not to strip, or snap those small bolts. Probably would not hurt to chase the threads first on the exhaust manifold.
Bob
 
For PO' folks that can't afford both NEW manifolds: IF, the "lugs" on one of the manifolds are CONSIDERABLY higher than on the other manifold, just carefully grind a "cut out" on the concave edge of the washer, mark it on the outside of the washer with a marking pen. THEN, carefully position the cut out over the HIGHEST mounting lug. CAREFULLY position the cut out, as you run the nuts down with your fingers, so the cut out remains in the correct place. THEN, tighten them down NORMALLY.
Bill W.
 
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