56 Chevrolet 3 Bolt Heat Riser?

[Mark S.]

I have a 1/2" thick 3 bolt heat riser with the word "UP" and not "TOP". Would this be correct for a late 56 Chevrolet? Thanks! Mark

[Gary C.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Heat riser with Top and 3 bolt is very early 1957. Correction - AFAIK late 1956 engines had a 3 bolt heat riser. Start date of 3 bolt manifold is unknonw.

Gary
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[Mark S.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Gary: Did the donut heat riser come later in 57 for the Chevrolets?

[Gary C.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Mark,

AFAIK the donut heat riser came in with '57 3 bolt exhaust manifolds.

TOP heat risers should be cast for the donut gasket

Gary
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[Mark S.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Gary Thanks!

The late 56 three bolt 1/2" thick "TOP" heat riser did not come with a donut. The three bolt 1/2 thick "UP" heat riser that I have has no provisions for a donut like the late 56 heat riser. So according to your information, the three bolt 1/2 thick "UP" heat riser was for early 57 Chevrolet production and the thicker heat riser with the donut came later in the 57 production. Is there a changeover date for the two 57 heat risers?

Mark

[Gary C.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Mark,

Do not have any Parts History info when 3725563 was replaced with 3731557 & 3731558, the late '56 exhaust manifolds, which were flat and had no provision for donut exhaust gasket, but the SR1 bill of materials shows a date of March 1956.

Correction - Photo of '56 2 bolt heat riser. '56 VIN4026 had a 3 bolt flat flange exhaust pipe and manifolds, with no provision for an exhaust donut gasket.
1956 2 Bolt Exhaust Heat Riser VIN4026.jpg

Correction - found this photo of a '56 heat riser with TOP, VIN unknown.
1956 3 Bolt Heat Riser - no doughnuts v1.jpg

My '57 VIN3004 FI car had a TOP exhaust spacer.

Gary
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[Gary C.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

1957 TOP heat riser with donut gasket on bottom side - VIN unknow
1957 TOP Heat Riser_top side.jpg 1957 Heat Riser TOP - side view.jpg 1957 Heat Riser TOP - bottom view.jpg

[Mark S.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

IMG_3709.jpgIMG_3709.jpgIMG_3710.jpgIMG_3711.jpg

[Mark S.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Gary:

The thread above with the pictures is the heat riser that I am trying to get information on.

Thanks!

Mark

[Gary C.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Mark,

All I can come up with for you is the '56 3 bolt heat riser part no. 3731396

Maybe Joe Lucia can come up with more info on the part no. for you.

Gary
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[Mark S.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Thanks Gary!

[Joe L.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Mark,

All I can come up with for you is the '56 3 bolt heat riser part no. 3731396

Maybe Joe Lucia can come up with more info on the part no. for you.

Gary
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Gary and Mark------


I'm not too familiar with these early heat riser valves. However, the GM #3731396 is the one I would opine is the one Mark pictures. Assuming that it is an early Chevrolet heat riser valve, that's about the only one it could be. The 3731396 was discontinued without supercession in October, 1967.

[Mark S.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Thanks Joe! This seems to be a mystery on usage.

[Mark S.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

I looked up the 3731396 in the GM Parts Books and it comes up for a 56 Corvette only. This would be the one with "TOP on it. The one that I have pictured has "UP" on it, so I am guessing that it might have been used in late 56 Chevrolet passenger cars or early 57s before the donut was used. This has been a tough puzzle to solve.

[Gary C.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Mark,

Early '57 Corvette such as VIN002 had TOP heat risers.

Gary
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