1964 heat riser function?
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Joined: Nov 2007
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From: Chicago
1964 heat riser function?
Can anyone tell me the purpose of the heat riser and its function? It is located on the passenger side between the exhaust manifold and exhaust pipe.
I do not have one on the driver side - should there be one there, too?
I do not have one on the driver side - should there be one there, too?
Le Mans Master
Joined: Apr 2004
Posts: 7,106
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From: Newark DE
it's function is to stay closed off when the car is cold to redirect the passenger side exhaust thru the intake manifold crossover passages to help speed up the warm-up process of the motor.
Once the exhaust gases warm up the bimetal coil spring on the heat riser it allows it to open up and the exhaust gases now pass normally thru the exhaust system on that side.
If you don't drive the car in the winter you can easily do without it. I took it off my '65 and replaced it with the available spacer unit as did many others on the forum.
If you want to take your car thru NCRS judging though they will deduct if it's missing
this is the heat riser here, next to my exhaust manifold
Once the exhaust gases warm up the bimetal coil spring on the heat riser it allows it to open up and the exhaust gases now pass normally thru the exhaust system on that side.
If you don't drive the car in the winter you can easily do without it. I took it off my '65 and replaced it with the available spacer unit as did many others on the forum.
If you want to take your car thru NCRS judging though they will deduct if it's missing
this is the heat riser here, next to my exhaust manifold
Le Mans Master
Joined: Sep 2003
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From: Norwalk ohio
2019 Corvette of the Year Winner
St. Jude Donor '15
my '64 had it and the car when cold wouldn't run worth a damn, but when I got the side exhaust on the car and did away with that thing, it idles GREAT and runs great all the time.....of course I don't drive it in the winter, so it makes no sense to have it...by the way it is a 327/365hp motor and runs much stronger since I put the side exhaust on as well....
Drifting
Joined: Apr 2001
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From: Holly Springs, Nort Cackalacky / Jupiter, Florida
If you want to take your car thru NCRS judging though they will deduct if it's missing
RK
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
depends I suppose. They do check proper operation of the heat riser during PV (Performance Verification) testing. During regular judging they probably wouldn't catch it.
Drifting
Joined: Dec 2006
Posts: 1,945
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From: Bronx New York
doug,
Unless you drive the car in cold weather, I recommend you use some wire to keep the riser in the open position. On my 67 I had a lot of problems with hot starts and fuel percolation in the carb bowls with today's gas. All this went away when i wired it open. Thanks to SWC Duke for the tip.
Unless you drive the car in cold weather, I recommend you use some wire to keep the riser in the open position. On my 67 I had a lot of problems with hot starts and fuel percolation in the carb bowls with today's gas. All this went away when i wired it open. Thanks to SWC Duke for the tip.
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From: Washington Michigan
