I have installed the correct Felpro gasket set twice and the end pieces have leaked. Now I am doing it for a third time and would like it to work this time. These end pieces fit perfectly and have three tabs on the bottom that go into holes in the block where they mount. Felpro says to put a small dab of RTV on the ends of these where they meet the intake gaskets. They say do not use RTV anywhere else on these end pieces. I have made sure they did not shift or move when installing the intake, but they are still leaking. There are no intake bolts in the middle of the intake that would press down on these. There are two bolts on the end of the intake where the end gasket meets the intake gasket. Actually they are studs on the ends that hold the intake gasket and use a nut to torque along with the other bolts along the intake. The studs and nuts are on each side and front and back. My leaks are in the front.

I know some have said they use a 3/8" bead of RTV instead of the gasket. Others swear by the cork gaskets that some manufactures use. I would like to avoid having to do this again so I am looking for a method that works either with the Felpro (which I have a new set of) or some other way to prevent leaks. Thanks for suggestions. Sandy

Also can anyone with a 87-91 460 motor tell me what vacuum lines go to the vac tree in the back of the intake. There are three connections on the tree.

Bottom side with three tabs

Top side of gasket

 

Whenever I did this job, I believe we used a thick bead of the RTV on those curvy ends. However the second time I think we had a thin layer on top of the provided curvy gaskets but both ended up working fine.

 

you could try a gasket sealer... sort of a contact cement.. to hold it in place.

Or just use rtv instead of the supplied gasket. That is what I have done on the small blocks. Just give it the appropriate time to cure before start up.

 

When I installed a new intake, instructions said to NOT use the supplied rubber gaskets, and only use a 1/4" bead of RTV.
I have done so, and no leaks. I was hesitant at first, but followed instructions and works perfectly.

 

I installed new intake, and instructions said not to use the rubber end seals, due to possible distortion of mating surfaces.

Might be intake specific.

 

I’ve had great luck discarding the supplied rubber pieces and using a thick bead of RTV black on the front and rear china walls and the ends where it meets the intake gaskets. “The Right Stuff” made by Permatex is what I use and has a quick cure time.

 

I prefer the mega grey rtv. If you want to spend a little more, go to a gm dealership parts department and see if they still sell GMS rtv. It's the generals go to for leaky pan seals that they cant solve. And it freaking works.
We used it to seal the intake ends on our turbo 460 race engine, and when the waste gate failed and the boost went into kills mode it didn't leak. The pan gasket blew along with 4 pistons, the valve cover gaskets and rear and front crank seals. The GMS didnt budge.

 

I second this.

 

And I third it.

When my father and I went through a motor together, we used gaskets. They leaked. When I built my own engine, I used rtv like described, not a drop of oil gas leaked. I used ultra black.

 

I'm with the others on this. I used the rubber gaskets and they leaked. I used the "Right Stuff" and zero leaks. And it will take a lot to separate it when done.

 

I have only had success 1 time with cork gaskets. I now only use beads of ultra black RTV on china walls. No leaks ever with this method.

 

I make 4 studs for each corner. Hang the manifold gaskets, then set the manifold down & eyeball the actual space at the china wall.

Then lay a bead of appropriate thickness just touching the manifold gaskets, LET SET/SKIN for at least 10 minuets.

Then set manifold down square & ever so lightly press down (don't squash) so that the everything touches evenly. Let set again for another 10 minuets.

Then tighten with correct torque sequence.

It's worked for me multiple times.

 

Many thanks to everyone that replied. The general consensus is to discard the rubber gaskets which I am going to do. Hopefully the third time will be the charm. I'll let you great folks know how it turns out. Thanks again for your time and help. Sandy

 

Used the RIGHT STUFF on the front and back gasket area and no leaks so far. Just wanted to thank everyone for advice and help on this. Sandy

 

@sandymane I used Felpro gaskets for the parts that go into the heads- those use zero RTV.
For the front and back of the intake I used cork gaskets and slathered RTV like crazy, and it works great and has zero problems.