Heat Block Off Plates, 2X4's

[Steven B.]

Has anyone run the dual four manifiold to head heat passage block off plates on the street? If so, how did it perform, good, bad, noticeable?

Thanks,

Steve

[Clem Z.]

Re: Heat Block Off Plates, 2X4's

Has anyone run the dual four manifold to head heat passage block off plates on the street? If so, how did it perform, good, bad, noticeable?

Thanks,

Steve

i ran every aluminum intake manifold i ever owned with the heat riser crossover blocked even in the winter here in Pa. it sometimes take longer to warm up but it fixes all the rest of the problems like boiling gasoline and it does up the HP. i did this years ago when we did not have ethanol in the gasoline so it may not solve that problem

[John N.]

Re: Heat Block Off Plates, 2X4's

Has anyone run the dual four manifiold to head heat passage block off plates on the street? If so, how did it perform, good, bad, noticeable?

Thanks,

Steve

Steve
Almost always. I believe that the SR-1 cars came from the factory with the block off plates installed. The cars also came without a heat riser valve, I do not what should be expected when a person operation checks the car. (lost the points in Florida)There was a GM Engineering test on Engineering Number 6911 Corvette (56 #1009, Sebring #7) which showed that the car ran better with block off plates. I believe the test paper was in a early Restorer. I also believe that some C-1s came from the factory with plates in a envelope. Most of my experience was with a 57 Chevy 270 HP and a 62 409, both were used for extensive drag racing.
Regards

[Jerry B.]

Re: Heat Block Off Plates, 2X4's

Hello Gents, Where Can You Buy Blockoff Plates For A S.b.

[John N.]

Re: Heat Block Off Plates, 2X4's

Hello Gents, Where Can You Buy Blockoff Plates For A S.b.

Jerry
There is a vendor who sells good reproductions. (do not remember who). You can cut your own out of stainless steel.
Regards

[Clem Z.]

Re: Heat Block Off Plates, 2X4's

Jerry
There is a vendor who sells good reproductions. (do not remember who). You can cut your own out of stainless steel.
Regards

i cut mine from .005 thick stainless steel shim stock. i would just drain down the rad,loosen all the manifold bolts and slip the shim stock down between the 2 center bolts. i would bend a 1/8" lip on the top end to make sure they could not slip down in too far.

[Stuart F.]

Re: Heat Block Off Plates, 2X4's

We also did like how Clem notes, only for temporary summer use, we made ours out of a tin can. That gave you a little ridge to better grab a hold of when inserting or removing. One side affect of using block offs was when we ran glass pacs; that sucker would really rap off nice - specially when backing off at about 6500 rpm. I once went by the onlookers at the end of our qtr mile downshifting after blowing off a Corvette with my 56 Chevy. The guys said it rattled their car windows like a sonic boom.

Stu Fox

[Clem Z.]

Re: Heat Block Off Plates, 2X4's

that is why some FI engines had the cross over exhaust pipes under the engine as it cut down on the exhaust "rap" plus it did help a little with HP. blocking the heat riser crossover does change the exhaust note

[Stuart F.]

Re: Heat Block Off Plates, 2X4's

Clem;

I've mentioned this before but was told I must be dreaming, but wasn't there a set of GM intake gaskets that had a metal plate in the exhaust crossover with a small sort of oval hole (restrictor) in it. We used those a lot, specially in the winter, and we always referred to them as fuelie gaskets (probably incorrectly). We used, as I mentioned, tin can block off plates and they usually lasted the summer. Actually, I never tested them to see how long they would last before burning through; however, I was using headers and usually changed out the plates each time I got protested at the track (that was a hard way to make a few bucks).

Stu Fox

[Steven B.]

Re: Heat Block Off Plates, 2X4's

Thanks All! I recall reproduction plates and envelopes but cannot remember who was doing them.

Steve

[Clem Z.]

Re: Heat Block Off Plates, 2X4's

Clem;

I've mentioned this before but was told I must be dreaming, but wasn't there a set of GM intake gaskets that had a metal plate in the exhaust crossover with a small sort of oval hole (restrictor) in it. We used those a lot, specially in the winter, and we always referred to them as fuelie gaskets (probably incorrectly). We used, as I mentioned, tin can block off plates and they usually lasted the summer. Actually, I never tested them to see how long they would last before burning through; however, I was using headers and usually changed out the plates each time I got protested at the track (that was a hard way to make a few bucks).

Stu Fox

there were some SBC intake gaskets for later years that used a tube inside the crossover to heat rhe choke that had some type of hole in the block off plate and my guess that was to time the choke release. the only GM intake gasket i remember that had the full block off plates was for BBC. regular thin tin will burn thru that is why you should use stainless steel.

[Tom P.]

Re: Heat Block Off Plates, 2X4's

As I'm sure everyone realizes, ALL FI engines DO NOT have an exhaust crossover provisiion at the intake manifold. Yes, the 57-62 FI engines do have the exhaust corssover pipes around the oil pan. But for the 63-65 FI engines, there was no crossover whatsoever (intake manifold or ex pipe).
And none of FI engines had a heat riser valve, only the spacer.
Furthermore, whenever headers are installed on ANY engine, if the engine has any kind of provision for ex crossover, it is effectively negated.