How to seal up the rear of my intake manifold

[Jason R]

Hey all, looking for some pointers or a better method to stop oil leaks at the back of my intake manifold. I just installed some ED heads and a home ported streetmaster. First time together had a little pushrod to intake contact so I pulled it apart again and put the die grinder to it for clearance. real noisy valve train on startup. 2nd time together fired up and sounded great but it started leaking at the drivers rear intake onto the exhaust and ruined the show. Currently I'm using the cork gaskets glued down with gasgacinch and ultra Grey on top of them. Struck out or did it wrong cause it's leaking now. So I'm pulling it apart again and thinking of ditching the cork and using just black aresol " right stuff" sealer at both ends and hoping for the best. What are you guys running to seal these things or what else might help. I also am running a  vacuum pump on the crankcase pulling about 13" at higher rpms.
Thanks
Jason

[blykins]

I'm not a cork fan.  Silicone, Right Stuff, whatever your choice of poison is.  Make sure you start the bead higher up on the side gasket so that you have sealant around the oil drain holes. 

As for the vacuum, I would turn it down some.  When you're using a wet sump pan with higher vacuum levels (over 10"), you can actually start pulling oil off the wrist pins and other items that need to see oil.  If it's a street engine, I would regulate it down to around 8" to err on the side of safety.

[jayb]

I've had good luck with Ford TA-31 silicone sealer on the end rails.  I also do not like to use the cork on the ends; a bead of silicone sealer by itself works fine.

I've run up to 15" vacuum with a vacuum pump on the track, but I always disconnect the vacuum pump for street use to make sure there is proper splash oiling to all the internal components, as Brent noted. 

[Lenz]

Ford TA-31 is what was recommended to me when I built, went without the cork, worked perfectly.

[cjshaker]

Plus one on the Ford TA-31. Great stuff that was designed for the harsh environment of diesels. If you've got a big gap you may not have a choice but to use the cork gasket because no sealer will hold up under that circumstance. Or you could mill the intake to get it lower, provided you don't throw off the port matching. I'd still use the TA-31 in either of those scenarios.

[KMcCullah]

Heavy beads of Right Stuff out of the can will have air bubbles in it and will let oil migrate straight through the bead. This happened on my 504. I use the caulking tube Right Stuff now.

[afret]

If the leak isn't too bad, take a look at the rear china wall/intake junction with a mirror to see what kind of sealer defect you have.  If it's just a small area that is missing sealer, it might be worth a try to just clean the area well with carb cleaner to get the oil off and dab some new silicone over that area. 

[Jason R]

Thanks for the input guys I will give the TA-31 a shot
Jason

[My427stang]

I am a cork fan, and year in, year out, I am amazed others do not like it.

What I do is 3M yellow on cork and china wall, let it dry then stick glue to glue.  In 15 minutes it is rock solid and the cork is going nowhere.

Then I assemble with RTV on top, still wet.  It slides over the top as the manifold settles in. 

Let me tell you a wild secret, more often than not, I can REUSE the corks, because they lock in tight and are generally undamaged during disassembly.  You change the intake gasket, give them another light swipe of RTV for lubrication and they are still good.

That being said, you need to have room for them, if you don't they hold the manifold up. 

[mike7570]

X2 - what he said ^
I have had good success with all my intakes. Now valve covers, that's another story.

[blykins]

I guess I've just seen too many instances where cork would not work....aftermarket combinations where the ports lined up perfectly but there was a 1/4" gap between the intake and china wall....or you cut the intake to make the ports line up and cork would hold the intake up off the heads.  To me there is no advantage to cork so it's just much easier to lay down a bead in 15-20 seconds and set the manifold down.  Doesn't matter how much clearance you have on the ends, .020" or .200",  a sealant will span it.