C2 Intake Manifold Gasket

[67ragtop]

Does anyone have a good method for installing intake manifold gaskets on a 67 327/350? On my first attempt I installed the gaskets dry. The front rubber gasket popped out after I tightened down the intake. The second try I used some high temp sealer/tack to glue the rubber down to the block. This lasted until the engine got warm and then the front gasket popped out again. My third try I tossed the rubber gaskets in the trash and used black high temp RTV in their place. This lasted for 60 miles then developed a nasty oil lead at the rear by the distributor (I did confirm that it was leaking between the block and manifold). Each time I cleaned the block, heads and manifold and used new gaskets. I’m not sure what to try next.

 

[JohnZ]

The best place for the rubber end gaskets is in the trash. I've used a bead of Permatex "Ultra-Copper" high-temp RTV at each end instead on countless engines over the years (after thoroughly cleaning the mating surfaces on the block rail and on the front and rear of the intake), and have never had any leakage at all. It's also close to the engine paint color so you don't notice it.

 

[67ragtop]

Thanks John, I'll give the Permatex Ultra-Copper a try.

 

[Radar]

Make sure you give it time to cure. I saw a post somewhere on this site that gave the instructions. Try a search.


Regards,
Radar

 

[IH2LOSE]

The best place for the rubber end gaskets is in the trash. I've used a bead of Permatex "Ultra-Copper" high-temp RTV at each end instead on countless engines over the years (after thoroughly cleaning the mating surfaces on the block rail and on the front and rear of the intake), and have never had any leakage at all. It's also close to the engine paint color so you don't notice it.

Wasnt there an article on this is last months corvette enthusis ?

 

[JohnZ]

Yup - I wrote an article on intake swaps in the May issue that covered it in detail

 

[studiog]

I've been there a few times myself with the black rubber gaskets popping out. Seems to be worse if the head and block have been decked. I did as John recommended and replaced the gaskets with the Copper (orange color) RTV silicone. I cleaned the surfaces of the block and the manifold throughly and applied about a 1/4" bead in place of the rubber gaskets. I let it cure for a couple of days before starting the motor. You might also want to make sure your crankcase ventilation is in proper order.

 

[bradfordsvettes]

check the crankcase vent for sure you will get all kinds of leaks if it is not working right steve