intake manifold gasket fit

[studiog]

Hi everyone,
I am rebuilding my motor and everything is going fairly well with some minor setbacks. Well today I ran into another minor setback. I am trying to install an aluminium 2x4 intake and when I lay it into place there seems to be a big gap between the gasket and the manifold so great that it would take just about another thickness of gasket to get a proper seal. The gap in fairly even top to bottom and side to side. I am using a generic gasket set ( Mr Gasket ) suppose to be for 265-350 motors. Does the aluminium manifold use a heavy gasket for some reason? :confused
Thanks for any help guys.
Gary S.
My Vette is a 61 w/283-270Hp

 

[WayneC]

I'm having difficulty envisioning the problem from your description.

The manifold mounting surface is slanted on both sides (where it mates to the heads), flat on the ends (where it mates to the block). Are you saying the flat ends don't allow the manifold to sit low enough for the side surfaces to contact the gaskets on the heads? If so, then something is keeping it up too high.

Will it sit low enough if the rubber end gaskets are completely omitted? If so, and there is a small gap at the ends when the ports surfaces are mated (with the side gaskets in place), you might be able to use a bead of blue silicone in place of the rubber gaskets to get it to fit.

It's also possible you don't have the rubber front and rear gaskets seated firmly/properly, especially at their ends, so they overlap the side port gaskets too much (maybe you stretched them while placing them? maybe you need to shave a bit off?)... pay attention to how the end gaskets mate with the side port gaskets. The end gaskets are a bit tricky to fit, so many people use the silicone bead I mentioned in lieu of those end gaskets just to avoid the issue. I generally wipe a very thin coating of silicone sealer on the bottom of the end gaskets to glue them in place on the block before lowering the manifold into place.

Or, I suppose it's possible that someone shaved the side port-sealing surfaces of your manifold, but that seems very unlikely. You could check to see if your old manifold fits properly when the aluminum one doesn't.

Chevy's parts book shows the normal 63-68 small block gasket set is used for the older 2x4 manifold.

If I've misunderstood your description of the problem, set us straight.

 

[71zman]

A couple of observations:
1) I recently put a Edelbrock Al manifold on my C1 and the installation instructions warned in bold print to use a gasket set that was made for a Al manifold.
2) Sometimes with older engines where the heads have been resurfaced many times, the fit is a problem. A trick to use is to throw away the rubber front and rear gaskets that came with your kit and use a bead of silicon sealer (blue RTV) between the heads. Make sure to lay a big enough bead that it excess sealant comes out when you bolt the manifold down. Also run the bead all the way to the manifold gaskets. This was also the recommendation of the Edelbrock Manifold installation guidelines.

hope this helps....

 

[studiog]

I see a recurring theme here so I removed the front & rear rubber gaskets and now I have an excellent fit. You were both right about that. The heads were resurfaced and the block was decked. Do they make the silicone sealer in black? That would look almost stock if they did. Anyway thanks for the help and full speed ahead till the next obstacle. Your help is greatly appreciated.

 

[pauk]

The best silicone sealer to use on the ends of the manifold is Permatex "Ultra Black". When it dries, you can trim it flush with the edge of the intake with a single edge razor blade and it looks almost like the stock gasket (except for the 'tabs', which you can glue on if you wish). Make sure you use the 'Ultra' Black and it will not leak!

 

[studiog]

Thanks everyone for the very helpful info!