Intake manifold gasket tips

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evilunclegrimace

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The only Iron intake that I have seen on a 5.7 TBI engine was in a G 30 van. Every C/K truck with a 4.3 or 5.7 came with a aluminum intake. And it is China rail.
 

packer0440

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My '88 original 4.3 was aluminum.
The 5.0 I swapped in from an '88 2500 was aluminum.
My '89 1500 original 5.7 intake, under the Whipple, is aluminum.
My '95 5.7 is aluminum.
The lower halves of the 5.7 Vortecs on the 5.7s on my '98 Suburban 2500, and my "00 Yukon are aluminum.

I never seen a smallblock iron TBI intake. Carb intake yes, not EFI.

As for the big block, do you have an actual TBI intake or a 2bbl carb intake with a TBI adaptor?


O.P.: ditch the rubber, use RTV.
The 1990 has the 4 barrel one (mark IV). The 92 has the actual TBI intake but it’s still iron.
 

someotherguy

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OP has a small block TBI, factory intake is aluminum. So much back-and-forth from an incorrect comment by someone saying it has to be aftermarket because OEM are cast iron. They're not. :)

Rebuild the TBI unit? Maybe.. if it's behaving, leave it alone. You can easily rebuild it later if you need to. Change too many things at once and you might wind up scratching your head trying to figure out why it won't start/run correctly after re-assembly.

Do be sure you get new o-rings for where the fuel lines attach to the TBI, though. A leak here may go unnoticed until it's an engine fire.

Sealant on all the bolts won't hurt; the outer ones are in the coolant but the inner ones aren't. However, the inner ones go through into the lifter valley and oil can creep up them if they're not sealed, and pool in the intake - something you've probably seen before.

I did a whole write-up on TBI small block intake gasket replacement but thanks to Godaddy holding my domain hostage, it's currently defunct, as far as pictures go. Let me see if I can revive it in a post here with the pics added.

EDIT - just did it. Merry Christmas or something, LOL: https://www.gmt400.com/threads/tbi-small-block-intake-gasket-replacement-pic-heavy.60383/

Richard
 
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Schurkey

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One tip I have for RTV is follow the manufacturer instructions. Most will call for allowing the rtv to “skin over” before assembly.
Permatex recommends NOT letting the RTV Silicone "skin over".
For example, the instructions for The Right Stuff Black (or Grey) 1-minute Gasket Maker say to "Assemble parts within five minutes, tightening bolts to recommended torque levels."
(Click on "Instructions")

Other products say to "Assemble parts immediately while silicone is still wet. Finger tighten until material begins to squeeze out around flange. Allow to dry for one hour, then retighten 1/4 to 1/2 turn."
(Click on "Instructions")

Different RTV Silicone products, different instructions.

When I replaced the TBI intake gaskets on my K1500, I used The Right Stuff (Black, aerosol, 1-Minute) on the China rails (so named because the ends of the block rise up from the lifter valley, and curve back and forth like the Great Wall of China) but NO RTV on the gaskets except where they meet the China Rail--I use gasket sealer to stick 'em to the head.

Fel-Pro says their gaskets don't need sealer. Hard habit to break, though. And I don't like having them flop out-of-position while I drop the manifold in place. So Gasgacinch (or High Tack, or Copper Coat, or any one of a dozen NON-RTV SILICONE products can be used.)
 
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eran tomer

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when applying rtv on the china rail and extending 0.5 inch more onto the cylinder heads as per the books- does the 0.5 inch go under the gasket or over the gasket? and why do you need to do so?
 

PlayingWithTBI

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does the 0.5 inch go under the gasket or over the gasket? and why do you need to do so?
Here's what we do, run a light ring of "The Right Stuff" around the water ports too, then set the gasket in place. The tabs on the gaskets will go into the end of your china rail line so, you just squeeze a little dab over it to ensure it's sealed when you drop the manifold over it.

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