Replaced the entire exhaust system on my 71 including the heat riser. The Riser has a spring and metal coil. I thought as the motor got hotter the metal in the coil expanded and opened up the valve. What is the purpose of the spring--I don't see that it does anything. How can something this simple not work. Am I missing something obvious.
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Re: How Does the Exhaust Heat Riser Work?
Paul,
Take a look at the first thread in the archives below.
On a C2 Heat Riser, which I think is the same on your 71, the coil only opens it up about a third of the way. Exhaust gas pressure opens it up the rest of the way, because of the eccentric pivot.
I think the little circular spring is just an anti-rattle device.
If you are heated up and you step on the gas, and you see the heat riser fully open, I think you are OK. I have the one on my 67 wired full open for driving, take the wire off for judging.Jerry Fuccillo
1967 327/300 Convertible since 1968 -
Re: How Does the Exhaust Heat Riser Work?
Heat risers contribute to premature exhaust replacement on the heat riser side. Have the heat riser on my 68 and 70 wired open to give longer muffler life.Comment
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Re: How Does the Exhaust Heat Riser Work?
To add to Jerry post, there are actually two springs (one coil) involved. The small spring that is attached to the shaft and pin is an anti rattle. The "coil" or relaxing spring weakens as it's heated allowing the weight to fall and open the baffle. It will still only open partially until enough pressure from the exhaust forces it to open completely.Comment
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Re: How Does the Exhaust Heat Riser Work?
Wouldn't you qualify wiring them open on the basis of ambient conditions. i.e. summer or Florida? You really need it for quicker warm up in the winter months which, in itself, can cancel out some of the pre-mature right side exhaust rot. I am going to pull mine from my 63 340 hp and replace it with a fuelie spacer. I live in Florida and have tested first with it wired open and it works fine here. Actually, it is difficult to get full choke here except in the cooler months.
Stu FoxComment
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Re: How Does the Exhaust Heat Riser Work?
I wired the heat riser open on my 67 sb based on a recommendation from this board (Duke ?). The car immediately ran better and the problems I had with hot starts due to fuel percolation in the carb were gone for good.
The choke may take a while longer to kick off in cool weather, but that's a small price to pay.Comment
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Re: How Does the Exhaust Heat Riser Work?
John;
Thanks for your report. I too have gone down that road, but have not completely tested as yet. I complained about the "Stinky Garage" before and got similar advice. I have to make sure I get it right to make peace with the wife. The smell of gas scares her in our attached garage.
I considered a fuel recovery system, like a charcoal canister hooked up temporarily to my AFB vent tubes, then using it to draw off upon restart. Have no final plans as yet.
Stu FoxComment
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