So I have a Edelbrock Performer Air Gap Intake Manifold for a SBC their part number 2601.

This intake manifold has no provisions for rear water jackets due to the design of the intake manifold.

Edelbrock's website says it's a street intake manifold, not a word or picture about not having rear water jackets.

My quandry is I cannot find any intake manifold gaskets from anyone that completly block off the rear water passage in the cylinder head where it would line up with the non existant rear water ports on the Edelbrock 2601 air gap intake manifold.

I may be over thinking it, but it seems like IF I don't block off the rear water ports on the heads it's going to leave a spot for water/coolant to sit, rust and or leak. I saw something like this occur on my friends 1990 sbf 302 in his mustang that had been sitting in his garage for years; the water/coolant ate through exposed machined surfaces on the thermstat housing and water ports on the intake manifold, heads were unaffected. That was a ford factory aluminum intake manifold. It was so bad it had to be replaced. When trying to find a good used one 9 out if 10 had the same problem.

So that's another reason why I'm concerned about this gasket issue. Edelbrock reccomends their 7201 intake manifold gasket set and it looks like most every other sbc intake manifold gasket set i've seen. Moreover, their pdf instructions for the intake and gasket set says bupkis about the non existant rear coolant passage on their 2601 air gap intake manifold.

My google fu is not finding anything either.

I found one set of felpro intake manifold gaskets that have all but like a 1/4" hole blocked off on the rear coolant passage, but again it seems like I need a block off and not a restrictor.

It seems like silicone & some kind of homemade blockoff gasket is the only way to do this right IF it needs to be done at all.

thanks in advance.

 

The vast majority of factory intake manifolds don't have a water port back there either. They just block it off. There's no problem with that, that I know of. Never heard of or seen any kind of problem caused by it. Can't see where there's any need for making blockoffs and all that.

Sounds like what you've seen on the Frods was dissimilar-metal electrolysis. That's not related to lack of a blockoff in any way.

 

how are they blocking it off? do you know of a over the counter intake manifold gasket set or block off gasket?

Or is everybody just cobbing up something of their own?

thanks in advance.

 

By casting a solid piece of whatever (aluminum, cast iron, whatever) that doesn't have a water passage in it.

No I don't know of any OTC gasket or anything else that does that, because it's totally unnecessary. There's like A BILLION SBC motors out there that have exactly what you have, and run for DECADES ON END without any problems whatsoever.

I think you're getting yourself all worked up over a potential solution to a problem that doesn't exist.

No. NOBODY is.

 

Not an issue like was said, the intake is the block-off.

 

I imagine that the water passage is on both ends of the cylinder head so that the heads can be used on either side of the engine. It’s not for the purpose of having a crossover on both ends of the intake manifold. If it did, the thermostat would be bypassed.

 

It is definitely true that the rear passages exist because the heads on the 2 sides are identical. Whatever feature one finds at the "front" of one head, for example the temp gauge sending unit hole, one will also find at the rear of the other; the fan switch, or a pipe plug, in the example I cited.

However:

No, completing the passage between the heads at the rear, would not bypass the thermostat.

The t-stat connects the point where the water exits out of the 2 heads at the front of the engine, to the outlet to the radiator. Its function is not affected by any other connection(s) between the 2 heads.

If the rear passages in the heads are connected across the intake (which some intakes do; not many, but a few), little or no water would ever really want to flow that way anyway, as the same pressure exists at both heads.

 

The C4 Corvette uses the rear ports as a crossover on their TPI intake and as a small line out point.

I've pulled an intake to see those rear ports with bone dry pockets 3-4 inches in on both heads. That's why I like to use small lines from the rear ports.

 

That was one of the ones I was thinking about... I think actually a couple of the TPI intakes are set up kinda that way.

 

1995 GMC truck 305 TBI has a rear crossover that is the inlet to the heater core.
The gaskets with the 3/32" holes are used for this.

If you really can't sleep unless you fully block those ports with a gasket, then use the Fel-Pro MS93317 and fill the small hole with Permatex.