Air Gap Manifold doesn't fit 318

[RockinRachel]

I bought (what I thought was an Edlebrock) aluminum manifold for my 1968 318. I tried to install it today and found it doesn't fit. When it is flush with both heads there is like a 3/8 inch gap between the top of the block and the bottom of the manifold. Am I missing something?

 

[R413]

What do you think the measurement there should be? The SB intake doesn’t fit flush with the block on the ends. There is a foam seal that goes in there, or you can use sealer.

 

[Backrd.Junkyard]

Pictures?

 

[RemCharger]

There's a fat cork gasket for each end that should come in the gasket kit.

 

[BeepBeepRR]

 

[Kern Dog]

Those cork gaskets are meant to be slightly compressed and they measure less than 1/4" right out of the box. IF there really is a 3/8" gap, the heads may have been heavily milled, causing the intake to sit up too high.

 

[JoePole]

Normal assuming with the intake gaskets in place. Most use a good quality oil/temp resistant silicone and don't be shy with it but you don't want it squeezing out into the engine. Don't forget the corners. Also a good idea to put a light coating around the water jacket passages on head and intake.

 

[rumblefish360]

Life long small block guy here.

Routinely, a head of RTV is used to form a wall of that 3/8 height to seal the intake manifold. Run the head of RTV into the four corners and a light coat around the water ports at each end and side of the cylinder heads.

The end seals in the picture above are normally not used. Normally I deck the block for a zero deck height w/the pistons. The intake also gets cut to fit flush. This sits the intake very low. In both cases, the ends seals are thrown out.

 

[451Mopar]

There should be a small gap on each end. Gasket or RTV to seal the gap.
The important thing is how do the bolt holes line up with the cylinder heads?
That will relate to the port alignment.
Without gaskets the cylinder head bolt holes should be at the top of the manifold holes, and when you add the gaskets, the holes should be centered.
If the heads or block has been milled and the head intake surface not milled to account for it, the manifold will sit too high on the heads.
If the manifold sits too high on the heads, you might need to have the intake milled to fit.

 

[WileERobby]

 

[YY1]

Dowel pins?

 

[toolmanmike]

I bought (what I thought was an Edlebrock) aluminum manifold for my 1968 318. I tried to install it today and found it doesn't fit. When it is flush with both heads there is like a 3/8 inch gap between the top of the block and the bottom of the manifold. Am I missing something?

Aftermarket intakes don't usually have holes drilled on the ends for the locating pins. You either have to drill holes or pull the pins. The front and back area's where the locating pins are are called a "China Wall".

 

[BeepBeepRR]

 

[33 IMP]

Life long small block guy here.

Routinely, a head of RTV is used to form a wall of that 3/8 height to seal the intake manifold. Run the head of RTV into the four corners and a light coat around the water ports at each end and side of the cylinder heads.

The end seals in the picture above are normally not used. Normally I deck the block for a zero deck height w/the pistons. The intake also gets cut to fit flush. This sits the intake very low. In both cases, the ends seals are thrown out.

Rumbles post auto-corrected "bead" to "head". He's talking about a bead of silicone, NOT the cylinder head.
OK, carry on...

 

[RockinRachel]

Rumbles post auto-corrected "bead" to "head". He's talking about a bead of silicone, NOT the cylinder head.
OK, carry on...

Things look different in the better light this morning. There is a small lip on the edge of the heads that is keeping the manifold from seating all the way down. I think if I grind that lip off the manifold will seat better. I suspect I will still need that bead of silicone on the ends though.

 

[62 Dart Convertible]

Things look different in the better light this morning. There is a small lip on the edge of the heads that is keeping the manifold from seating all the way down. I think if I grind that lip off the manifold will seat better. I suspect I will still need that bead of silicone on the ends though.

You absolutely will need sealant on the ends. I always threw the gaskets out and just filled it with good silicone sealant.