Head question..

[Phoenyx]

My Edelbrock intake came with steel plugs to insert into the heads to block the crossover.
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Yeah, I think most new intakes come with those. I've also seen them in gasket sets.

 

[GMNorway]

Ok, so this heat riser valve you is talking about is it inside the manifold? 😳

The recessed area between the center exhaust ports on my 7a heads are missing some mm to meet the exhaust manifold.
If u know what i mean.. Seems like it's done from the factory ?!

All of my intake manifold that i got are those stupid egr stuff 🙁 So a performer will be the thing to buy, non egr manifolds is hard to get here.

 

[DoubleV]

Ok, so this heat riser valve you is talking about is it inside the manifold?

It's just a valve on the end of one of the exhaust manifolds. The older ones used a thermal spring, in later years they were vacuum operated ( vacuum applied only when cold and contoled by a thermal vacuum switch ).

When the engine was cold, the heat riser valve would be be shut. This 'backs up' the exhaust on that side of the engine. This 'backed up' exhaust has no where to go except through the crossover in the head ( center of the head ) which conects to the crossover passage on the intake manifold which runs under the carb, then into the crossover port in the other head, and out the exhaust ports.

When the engine warms up, the heat riser valve opens and the exhaust flows as normal.

Even without a heat riser valve, there is still heat from the exhaust that 'crosses' over under the carb to keep it warm. This is one reason why many fill in the crossovers....no heat under the carb for more HP.

The recessed area between the center exhaust ports on my 7a heads are missing some mm to meet the exhaust manifold.
If u know what i mean.. Seems like it's done from the factory ?!

This is normal. I wish Olds didn't do that...

All of my intake manifold that i got are those stupid egr stuff 🙁 So a performer will be the thing to buy, non egr manifolds is hard to get here.

You can still use an intake with an EGR provision even if you're not running an EGR valve or the crossover.

 

[GMNorway]

Good info about that subject 🙂

Are there any aftermarket block off plates for the egr valves ?
But i assume its a pretty easy job to make some 🙂 Ore just weld them shut.. :idea:

 

[DoubleV]

The Edelbrock Performer intake comes with a block-off plate, but yeah they're pretty easy to make. If you don't mind the ugly look, you can even just leave the EGR valve on just don't hook the vac line to it.

 

[RITTER]

WoW
That's what I meant. I didn't mean water jacket 😳

 

[83hurst-olds]

I was going to say, I usually promise her a few things, bring flowers and claim ill return the favor. lol jk

That's pretty much what I was thinking... Usually even that still doesn't produce head.

 

[455rocket]

It took a ton of time carefully filing them to get them to fit but it worked.

Ya got that right Blake, what a pain in the *ss. This is also used for the choke, if ya block it ya gotta run an electric one. Blockin them up will also keep your paint job nice, thats the main reason I did mine.