Intake manifold won't seal - How do I check it ?

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duster360

duster360

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I have a 6 pack intake for my small block. Everything is brand new. To start with I used the Fel-Pro gaskets in the gasket set. They were roughly .040" thick. They leaked at the bottom of every intake port. I bought a set of Edelbrock .060" thick gaskets. Still leaking ( pulling oil in from the lifter valley ) at the bottom of every port. I need to check the angle of the heads vs. the angle of the intake. I have an degree angle finder like you would use setting up driveline angles. And also an adjustable angle setting tool. What would be the best way to go about doing this?
 
Man, that is a great idea. I would never have thought do that. Thanks for that tip.
 
Those magnetic pendulum style angle finders are no where near accurate enough for this task. 2 tenths of 1 degree discrepancy is enough to cause problems.
 
Unless the heads are warped end - to - end you should be able to set a clean dry manifold down onto a clean dry engine and SEE it, just sight straight "into" the front of the engine. If it's in the car, use a mirror.
 
67Dart273 said:
Unless the heads are warped end - to - end you should be able to set a clean dry manifold down onto a clean dry engine and SEE it, just sight straight "into" the front of the engine. If it's in the car, use a mirror.
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I put a straight edge on the manifold and it looks like the surface is straight from front to back. But it seems like the the angle is off from top to bottom.
 
You can tell the gasket is crushing pretty good along the upper side but not so much towards the botto.
 
If everything is together and running then choose your favorite flammable spray and go around the edges. You will hear the rpm go up very little for a leak. I would use the plastiguage though
 
doogievlg said:
If everything is together and running then choose your favorite flammable spray and go around the edges. You will hear the rpm go up very little for a leak. I would use the plastiguage though
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I have oil pulling into every intake port on the heads. So it is all of them.
 
I've run across a few intakes that were bent when they were sucked down over the locator pins, when there was no reciprocal holes in the manifold, front and back..

They sucked oil as you described,, from the bottom of the gskts... also had pin impressions in the manifold..
 
There are no locating pins in the block. But this intake does have the pin holes in it if I wanted to use them.
 
My machinist came over today and looked the situation over a little. He told me to try a .100" thick gasket if I could find one. If not he would look around for me. He said this would be the first and cheapest step. If this didn't work then he would possibly have do some machining work and that would be a lot more than a set of gaskets, which is what he is trying to help me avoid.
 
I had this problem when I used a 318 manifold on a 340. I was leaking on the top. So I didn't even bother to look at the bottom. Could this be you?
 
Nope. 340 6 pack intake on a 340. Top seals nice and tight. Leaks real bad across the bottom.
 
Which gasket are you using? I always use the pinto seal type. Is that the mopar 6 pack intake?
 
Second set was edelbrock .060" thick gasket with the sealant around the ports. Yes, it is the Mopar six pack intake , not the original edelbrock.
 
How much are your heads milled?
For every .010 off the head you have to take about .012 off the intake to get it to align properly.
How do the bolt holes align?
How is the alignment with no gaskets in place?
 
Sounds like intake and heads milled at different angles, for sure....

How about this....properly torque down the intake with a new set of gaskets(no sealer!)...let it sit a while (overnight?)...then remove the intake, then the gaskets (carefully) and "mic" the top and bottom of the gasket intake ports . The difference in thickness should give you an idea of the angle difference...ballpark figure at least.
 
sireland67 said:
How much are your heads milled?
For every .010 off the head you have to take about .012 off the intake to get it to align properly.
How do the bolt holes align?
How is the alignment with no gaskets in place?
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To my knowledge these heads have never been milled. They have been in the family since 1975 and retired in 1980 until recently when I took them to be reworked. Bolts holes alignment is good. I am going to check the intake on the engine again this evening to see if I can see any alignment issue at the bottom.
 
65Val said:
Sounds like intake and heads milled at different angles, for sure....

How about this....properly torque down the intake with a new set of gaskets(no sealer!)...let it sit a while (overnight?)...then remove the intake, then the gaskets (carefully) and "mic" the top and bottom of the gasket intake ports . The difference in thickness should give you an idea of the angle difference...ballpark figure at least.
Click to expand...

I have a spare set of gaskets, I can try that.
 
Heres a question and its something Ive never read any talk about. When you replaced the heads how thick of a head gasket did you use ? If you went from a stock .028" to a .040" fell pro I would think that would cause the intake to need a gasket around .012" wider then stock also. Ive never heard of this being an issue before oddly enough.
 
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