Sealing aluminum instake to aluminum heads

I rebuilt a 302 and have had a ton of small problems. I still thing I have a vacuum leak, so I pulled the instake manfold back off. Before I put it back on I was hoping someone would have some advice form me on using a sealer on the gasket between the aluminum intake and the aluminum heads?
After this thread I'm sure there'll be more questions I'll have about carbs, but one thing at a time.  

has the block or heads been shaved, if so the intake may bottoming out on the block, before the gasket is tight enough, also check the intake with a streight edge to make sure it flat.  

I like to use a thing layer of non-hardening sealer on intake gaskets. Something like Permatex #2 or Hylomar Blue Racing Formula, etc.

Do not use Fel-Pro performance gaskets. They are designed for short term use (drag racers pull their stuff apart every few races). Use the Fel-Pro standard line gaskets or your other favorite brand.

I also put a thin later of silicone around the water ports at each end of the heads.

As for the end rails, some swear by a large bead of silicone, some use cork or rubber end seals, and some use a combination.

However, Packman is right, if your block has been decked or the heads cut/shaved, you might be bottoming the intake against the block before it seals against the heads. Dry fit the manifold with no gaskets and check for acceptable clearances you know will seal with the gasket in place.

HTH...
Mark
.  
Mark Houlahan
Technical Editor for:
-Modified Mustangs & Fords Magazine
-Mustang Monthly Magazine

1965 FFR Roadster 427W/TKO-600 5-speed
1966 Mustang 289-4V/C4 Auto
1968 Mustang 4.6L Three-Valve/5R55S Auto
1990 Mustang 306/AOD
2002 Explorer Sport Trac 4.0L V-6/5R55 Auto

The heads and manifold are new, so they should be in good shape. I’ll pick up the sealer tomorrow and put it back together, keep your fingers crossed.
Thanks for the info, that’s what I was looking for.