[71ModelJ]

Got a set of Pontiac heads that I want to block the heat crossover on. I know a lot of them are filled with aluminum but isn't there a Fel Pro or other manufacturer that impregnates a plate in the gasket. I've used them on big block chevys. Any help?

[Pontirag]

I have found that if you slip a piece of thin stainless steel shim stock between the gasket and the head on both sided it usually last quite a while

[71ModelJ]

Originally Posted by Pontirag

I have found that if you slip a piece of thin stainless steel shim stock between the gasket and the head on both sided it usually last quite a while

Thats the same idea as the Felpro ones for the big block chevys. I was just wondering(cause I can't find it) if Felpro makes them for Pontiacs.

[Formulabruce]

I think that I had some loose ones in a felpro Pontiac kit, just for that. That was a few years ago

[Captainofiron]

Originally Posted by Formulabruce

I think that I had some loose ones in a felpro Pontiac kit, just for that. That was a few years ago

+1

I had some too, they look just like stainless inserts and they have a little lip so it sits around the hole on the head

[limejudge69]

Mr Gasket intake set has the blocking tabs. Part number 502G.

[steve25]

Yes a metal shim will block it off but it does not make for better header tuning if that`s what you are looking for also. The two center ports are still connected to one another and upsetting the Intake flow with unwanted reversion.
This is one of the reasons why Pontiac made these passages smaller with the 5C,6C,6X and 6H castings.

[71ModelJ]

Originally Posted by limejudge69

Mr Gasket intake set has the blocking tabs. Part number 502G.

Thank's for the tip

[sts]

Felpro # 1233

[tjdjr]

The edelbrock gaskets come with an insert to block x-overs.

[brgrenier]

Does anyone pictures of this?

[61-63]

Originally Posted by brgrenier

Does anyone pictures of this?

Google MrGasket 502G or Felpro 1233 and you will get a picture in one more click.

[limejudge69]

here ya go

[Ed Fitzgerald]

I'm in the process of doing a set of 141 heads with aluminum. I think if I was to block the heat crossover with only a stainless shim plate the very least I would do is stuff the area behind the exhaust valves with steel wool in an attempt to push as much exhaust gas into the manifolds as possible. Then in the off chance you didn't like the performance mod you could remove the shim plate and steel wool and carry on. If in fact you liked it you could opt for a more permanent fix. IMO

[lust4speed]

In SoCal we don't miss the manifold heating, but if you drive in colder climates you might want to factor that in. If you only drive the car in fair weather, then blocking the passages and going to an electric choke could be a viable option. Even in warm weather here, the choke has to be locked open or an electric choke conversion installed. Without the manifold heat, it will take 15 minutes or longer for the manifold temperature to warm up enough to pull a normal choke off.

I don't think steel wool would last, but I've read on here about people tightly packing the crossover passages with aluminum foil. I haven't tried it so don't know if it lasts or not. I have poured aluminum and used Resbond with excellent results. Just do a search for Resbond and you should come up with a couple good threads on the matter. If nothing else, separating the exhaust ports sure sweetens the exhaust sound.