MBELTRAN
Contributor
Posts: 145
Reg: 02-17-15
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01-21-23 05:35 PM - Post#2853595
Ive recently taken out my long tube headers and in the process of putting in ram horn exhaust manifolds in a 1961 impala. The exhaust kit i have on the car requires me to put the heat riser in order for the pipes to line up properly.If not the exhaust would hit the starter. I know they make spacers but dont feel like spending 60 plus on literally just a spacer when the heat riser i have is in really good working condition. It is not the original motor to the car. It is a 355 with edelbrock intake manifold and edelbrock AVS2 carb with electric choke, I have a few questions. Ive be doing some resrearch on this and been reading how the heat riser and the (original) manifold play off eachother and somehow the heat riser redirects the air back into the manifold and if you have it blocked off it could cause some kinda BS like that or something. Man honestly i dont know, i got lost in all that. Just looking for a simple yes it will work or no im gonna have some issues. Like mentioned i have an edelbrock manifold and avs2 carb with electric choke. Will i have any issues running the heat riser with this? Thanks for any help in advance.
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SSuper Dave
Member
Posts: 506
Loc: Pearland TX
Reg: 10-02-05
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01-21-23 06:01 PM - Post#2853597
In response to MBELTRAN
Just get the spacer, you will be glad in the long run. I wouldn't trust the valve to work right.
1968 Caprice coupe, 327/275, TH400, Ash Gold/Ivy Gold, Tach Dash, Tilt, Buckets, Console, AM/FM, Rear Defog, Disc and Rallys.
1970 El Camino, 350, TH400, 12 bolt posi, a blank slate! |
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 pvs409
"11th Year" Gold Supporting Member
Posts: 3529
Loc: Sergeant Bluff, Iowa
Reg: 01-10-05
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01-21-23 06:28 PM - Post#2853600
In response to MBELTRAN
No need to hook up the heat riser to your carb - that is what they are for to open a factory choke on a factory Rochester or Carter AFB used in 1963 by connecting a choke tube to a manual choke on those 2 carbs.
All those other notes about a heat riser are junk - only to open a factory choke.
Just use the heat riser you have and don’t hook a choke tube to it. Assuming your car runs fine now it should run as it does now.
Paul
57 BelairHT 283/270hp 4 spd
62 ImpHT 327/300 4 spd
62 Imp CV SS 327/300HP 700R4 (sold)
62 Imp HT SS 409/482 stroker 4 spd
62 Imp SS 409 - 5 spd Convertible
https://paulstensland.com
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 DonSSDD
Silver Supporting Member
Posts: 7895
Loc: Nova Scotia, Canada
Reg: 08-21-01
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01-21-23 06:32 PM - Post#2853601
In response to SSuper Dave
You can make a spacer from the existing heat riser, remove the flap and shaft it rides on , fill the shaft holes with JB Weld. You won’t miss it.
63 Pontiac Parisienne Sport Coupe(CDN Chev mechanically (409, 4 speed),1998 Silverado Reg Cab 4WD, 62 Bel Air SC (sold), 59 El Camino (sold), 62 Bel Air SC(sold), 63 SWC Vette (sold),
Member #2194
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MBELTRAN
Contributor
Posts: 145
Reg: 02-17-15
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01-21-23 06:38 PM - Post#2853603
In response to pvs409
No sir was not gonna hook it up. Just wanted to make sure or maybe i was overthinking it. So i should be good huh? The heat from the exhaust will open it up and having an electric choke wont fight eachother?
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pvs409
"11th Year" Gold Supporting Member
Posts: 3529
Loc: Sergeant Bluff, Iowa
Reg: 01-10-05
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01-21-23 08:37 PM - Post#2853604
In response to MBELTRAN
A manual choke Carter AFB or Rochester has a manual choke tube & heat from the choke tube heats a coiled spring inside the manual choke housing - that coil opens the flapper on the carb as the engine warms up. You do not have a manual choke on your carb with this type of connection.
Your electrical choke operates the same air flapper on your aftermarket carb. No way the electrical choke has any connection to the operation of a manual choke and heat riser flapper.
Wire the exhaust manifold flapper open if you want. So it does not restrict the exhaust gases as compared to the drivers side without a heat riser.
OR- as Don suggests remove the heat riser flap ( cut it out) and plug the holes in the exhaust manifold.
Paul
57 BelairHT 283/270hp 4 spd
62 ImpHT 327/300 4 spd
62 Imp CV SS 327/300HP 700R4 (sold)
62 Imp HT SS 409/482 stroker 4 spd
62 Imp SS 409 - 5 spd Convertible
https://paulstensland.com
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impala62
Contributor
Posts: 111
Age: 54
Loc: The Netherlands
Reg: 04-02-07
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01-22-23 12:22 AM - Post#2853605
In response to pvs409
There was a (heated) discussion some time ago about the heat riser.
Lots of good information if you ignore the discussion and just use the information.
if your manifold has the cross-over passage then it can be useful to use the heat riser, otherwise just use the spacer.
In my part of the world (the Netherlands) with sometimes temperatures below -5C = 23F I`m happy to have it working as it helps with cold drivebillety.
https://www.chevytalk.org/fusionbb/showtopic.php?t...
1962 327 4 door hardtop
1967 opel kadett 1.2ltr |
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Tony1963
Frequent Contributor
Posts: 2070
Loc: Orlando Florida
Reg: 07-09-18
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01-22-23 05:07 AM - Post#2853609
In response to MBELTRAN
The heat riser was a device to partially block the exhaust flow on the right side of the engine, forcing those exhaust gasses through the lower section of the intake where it could preheat the incoming air/fuel mixture. The idea was that it would atomize the fuel better than cold cast iron.
There were three pieces of technology that were used on the RH exhaust on a small block Chevy. Those are listed as follows:
Heat Riser
The heat riser temporarily limited exhaust from flowing out the RH exhaust manifold and routed the hot gasses under the floor of the intake to better atomize the air/fuel mixture. These were controlled by a bi-metallic spring until the early 70s, then replace by a vacuum pod that was sensitive to engine coolant temperature. This device prevents stumble and backfire in warmup. The later 70s version is known as EFE for Early Fuel Evaporation.
Heat Stove
This device created somewhat of a heat shield around the exhaust manifold and ducted warm air into the intake air stream for better atomization of fuel and was regulated by a thermostat in the air cleaner assembly. This device also prevented icing of the throttle blade as the air/fuel mixture went through the venturi where, as the fuel atomized, it lost heat changing into a vapor and could freeze the throttle. It is a necessary part of the system. On some engines, it was on the left side.
Choke Heat Source
These early versions were a steel pipe through the manifold. Later versions have the pipe sitting in a well on the intake manifold just above that crossover for the heat riser chamber described earlier.
| People fear change because it threatens what they know, or what they claim to know. |
Edited by Tony1963 on 01-22-23 05:11 AM. Reason for edit: No reason given.
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japete92
Posts: 2092
Loc: No. Virginia
Reg: 01-18-13
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01-22-23 08:32 AM - Post#2853615
In response to MBELTRAN
Ive recently taken out my long tube headers and in the process of putting in ram horn exhaust manifolds in a 1961 impala. The exhaust kit i have on the car requires me to put the heat riser in order for the pipes to line up properly.If not the exhaust would hit the starter. I know they make spacers but dont feel like spending 60 plus on literally just a spacer when the heat riser i have is in really good working condition. It is not the original motor to the car. It is a 355 with edelbrock intake manifold and edelbrock AVS2 carb with electric choke, I have a few questions. Ive be doing some resrearch on this and been reading how the heat riser and the (original) manifold play off eachother and somehow the heat riser redirects the air back into the manifold and if you have it blocked off it could cause some kinda BS like that or something. Man honestly i dont know, i got lost in all that. Just looking for a simple yes it will work or no im gonna have some issues. Like mentioned i have an edelbrock manifold and avs2 carb with electric choke. Will i have any issues running the heat riser with this? Thanks for any help in advance.
Simple answer is the heat riser will not cause any harm. Will it do any good? No; especially if your manifold does not have the built in conduit to below the carb (or it is blocked off), and you have an electric choke. In that configuration it is completely superfluous.
They are prone to seizing from corrosion. They can get 'stuck' either 'open' (not a problem), or 'closed' (inhibits exhaust flow).
Personally, I would use a spacer because there are no moving parts to 'fail'. But, I have read about folks who have removed the 'valve parts' to provide a permanently 'open' configuration. I have not done that; I opted for the spacer.
Here's some general info:
https://www.chevytalk.org/fusionbb/showtopic.php?t...
https://www.chevytalk.org/fusionbb/showtopic.php?t...
Recommend you consider 'Grumpyvette's' advice noted in the attachment to my comments in the second 'topic' above.
Pete
Edited by japete92 on 01-22-23 08:34 AM. Reason for edit: No reason given.
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