Silicone on intake end rails

[R.Brown]

I have always used a bead of silicone on the end rails of the block to seal the intake (chev, ford, dodge v8 stuff). We just finished up some intake manifold tests on the dyno and were switching between 3 different intakes. I was using Permatex "The Right Stuff" (Item #33694) and found that when we pulled the intake manifold, the bead had not set up yet (this one had 16 hours of cure time, with a 1/4" bead). It could be a heat related deal, as we pulled the intake off before running it to change something, so maybe it needed the heat in the motor to cure it...??? The parts were free of any oil, and very clean at assembly time. We switched to the Permatex #26C (red high temp) and the rest of the testing went fine. Any ideas, or is there a better silicone to use?

Thanks,
Ryan

[BigPurp]

Thats odd, I've always used the "right stuff" and found it seals better than anything i've ever used. It could be a heat issue, but kinda doubtful. I've used it for everything from diff covers, intake manifolds etc. If it didn't leak I wouldn't worry about it too much.

[learner]

I don't remember who makes it or what other name it's available under but i prefer the gray silicone or sealer you get from the Ford dealers made for the diesel engines when it comes to laying a bead.

[Shaffy]

I'd say it might be heat related... IMO, It usually takes 24 hours or better to fully cure silicone.. Warmth, will usually cure anything faster... Humidity may also play a role, but im not a chemist.. LOL