After three tries, I still have not been able to seat the intake on my sbc so that it won't leak along the back rail. The first time, I used RTV, without the rubber gasket. It didn't stick to the metal and was blow out on both sides. The second time, I used "The Right Stuff." It was nice and dry on the passenger side, but leaked badly on the driver's side. It's not like I didn't use enough. In fact, it was hard to get the intake off for the next try. On the third and most recent try, I used the rubber seals and put a thin coating of "The Right Stuff" on both sides of the rubber seal. That sealant is sticky. So, there is no way the rubber seal slipped off. In fact, I can see the tabs on the rubber seal, right where they are supposed to be. Now, it leaks on the passenger side, but is dry on the driver's side.

I'm thinking maybe the intake is warped. It's an Edelbrock Performer I bought used a few years ago. I crushed the ear on the back passenger side corner a few years ago before I figured out that my 20+ year old torque wrench was out of calibration. But, it still worked okay with my old 283. When I first started the new engine (new crate motor), it overheated and the radiator boiled over. Maybe, that did it. If it is warped, it figures it would leak on one side and then the other.

I'm a hack mechanic, but not so bad that I can't seat an intake manifold after three tries. This is really ****ing me off, especially because this is the only thing standing between me and being able to drive the car after a whole summer of dinking around with it.

Do you have a PCV system hooked up and running? Sounds like you may have an internal pressure problem thats blowing by the seal.

Alternatively did you THOROUGHLY clean all mating surfaces of any residuall oil before you laind the manifold in place. Silicone usually doesn't like to stick well to oily surfaces. I always shoot a bit of CRC Brakeleen on mating surfaces before I lay an silicone. The stuff carry's away oil and dries (evaporates) very quickly.

Finally then next time you go thru the R&R procedure make ABSOLUTELY SURE that the back of the block directly below the horizonatal gasket surface is also spotlessly clean. then, when the intake manifold is in place, take some silicone sealer and apply it by hand across the the gap between the intake manifold and the block. Allow it to set up overnite before you fire the engine.

Best of luck to ya! :)

Thanks for your reply. You always give good advice. I'll try everything you suggested.

The PCV is hooked up to the carb and appears to be working. In addition, there are breathers on the driver's side valve cover and oil fill tube.

I cleaned all of the mating surfaces with a scraper, carb cleaner sprayed on a rag and with clean, dry rag. I made some very small dimples in the rails to give the sealant something to grip. I did not check to see if the mounting holes are blind holes or if they go all the way through to the lifter gallery. If they go all the way through, oil could be weeping through the bolts. So, I'll put some sealant on the bolts, just in case. The block is plenty wet with oil at the corners of the intake. So, maybe that's it. But, it's wet in a few other places, too.

I still think that there is something up with the intake. I'm replacing it with a new Performer EPS. Maybe, that's not the problem. But, at this point, I would rather spend a $100 to get the car on the road than to keep on doing and redoing.

Sometimes, the simple things (or things that look simple but aren't) are the things that drive me nuts. The good news is that the engine runs very well. So, it's going to be really cool to get the car on the road and drive it.