The Rodding Roundtable
Motorhead Message Central => Rodder's Roundtable => Topic started by: Harry on May 03, 2015, 06:39:36 PM
I'm about to install an aluminum intake on a 350 Chev. It was on there before. The ends of the intake had a lot of grey silicone type stuff.
I have cleaned everything back to new. Now the question is, what is the procedure for putting that silicone on and what brand should I use?
Thank you for any help.
There are proper gaskets for the ends of the manifold.
I'm still using the stock black rubber (or whatever it is) gasket on the ends without leaks or other catastrophic results. I've never been fond of the bead of silicone process. I put a small dab of black silicone at the junction of the side gasket and end gasket.
Charlie
Most of the instructions for aftermarket aluminum intakes say to put a 1/4 inch diameter bead of silicone at each end. The rubber gaskets could hold the intake up if the heads have had a lot of machining on them. Or the tolerances from the factory on the manifolds could cause the same condition. I have one on a 340 Mopar that is not sealing. This will require thicker intake to head gaskets.. I use the Permatex black.
Don
Permatex Ultra Black. No end gaskets with aluminum manifolds.
QuoteI have one on a 340 Mopar that is not sealing.
Don .. I remember back when I had my racecar, we constantly had trouble sealing intake manifolds .. ( Big Block Mopars) At that time , Fel-Pro Gasket company made a very thin paper type "shim" gasket that we were able to move the intake up or down by about .030 or so... They would be used with the normal "pie-pan" metal gasket that sealed the top of the engine ..I don't know if they have any thing for the small blocks ...
I too use Permatex Ultra Black to seal the end rails on all aluminum manifolds ... The latest GM service instructions show the same thing ...
""Install RTV to the front and the rear sealing surfaces on the block. Apply a 5 mm (3/16 in) bead of RTV GM P/N 1052366 or equivalent to the front and the rear of the block. Extend the bead 13 mm (1/2 in) up each cylinder head to seal and retain the gaskets. "" ....
Hope this helps .....
Bob ... :wink:
I had heard different opinions on using stock rubber gaskets. Not sealing, blowing out, etc. I'm going to stake the block and intake with a centre punch and use rtv goo.
Thanks for your input.
Hooley's 974, when it had small block power, had sealing problems at the rear of the intake. Taking his intake off to reseal was a pain due to the supercharger. His block was staked but that wasn't enough to hold it. It was suspected the motor was pressurizing the block and pushing it out. An oil fire at 200+ is a bad thing so we never considered making another run until after the repair.
Sealing the rear of the intake is a common problem on the hot rodded SBC. I wonder why the front side doesn't leak as often?