Intake manifold 390

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Dec 16, 2012 | 06:39 PM

jetrinka

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Intake manifold 390

I hail from the world of inline 4-bangers (have an 88 Merkur XR4Ti as my go fast project) and this cam-in-block V8 world is a bit new to me.

Been re-sealing the 390 in my 75 F250 and it came time to put the intake manifold back on (jeez its heavy...). I put silicone in the 4 corners of the valley where the cork meets the composite gaskets (both on top of and under the cork in that corner) and then put the manifold on and torque things down. I noticed the cork towards the middle of the front and back of the engine squeezing out a bit far. Loosened the bolts up enough to tuck it back under and torqued things down again. Seemed to stay in place this time so I just left it. Is this typical or is my installation procedure flawed in some way?

Dec 16, 2012 | 06:49 PM

nine inch rear

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From: Dublin CA

Let it cure up and you should be fine. Lots of times we just use a thick bead of silicon because of that very same problem

Dec 16, 2012 | 06:49 PM

jetrinka

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Cool. Thanks for the quick response!

Dec 16, 2012 | 06:54 PM

turbohunter

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From: Northern and Southern Cal

You did nothing wrong.
It's a normal problem.
Let me put it to you this way.
My brother is a gasket manufacturer and he uses silicone instead of cork 'cause the cork is a PITA.
There are however folks that will only use cork and Permatex and swear by it.

Dec 16, 2012 | 07:01 PM

1972RedNeck

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From: Townsend, MT

The only gaskets I used on my 416 were the head gaskets and the side intake gaskets. Everything else was grey silicone. It is bone dry.

Dec 16, 2012 | 07:03 PM

jetrinka

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ha! It seems if the cork begins to leak it will be getting ripped out and replaced with silicone.

Dec 18, 2012 | 09:05 PM

f100cary

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The way that has worked best for me is to glue the end gaskets down and let them set for an hour or so. Then do the rest. Nothing moves and you have a real gasket at each end.

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Dec 18, 2012 | 09:30 PM

HIO Silver

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From: NorCal

Quote:

Originally Posted by jetrinka

ha! It seems if the cork begins to leak it will be getting ripped out and replaced with silicone.

Most engine builders will throw away the 'china wall' gaskets and use RTV. MCE Engines will take a punch and dimple the mating surface of the wall so the RTV has some bite. When laying it on - dab, backtrack, dab, backtrack. It should look like nice TIG welds but with RTV.

Quote:

Originally Posted by f100cary

The way that has worked best for me is to glue the end gaskets down and let them set for an hour or so. Then do the rest. Nothing moves and you have a real gasket at each end.

That works too... letting the RTV outgas for a bit lets it become firm and less prone to squirm out. Still, repeat heat cycles and age tends to dry out the cork making it brittle and more prone to leaking.