Heat risers, how are they supposed to work?

[Brian M.]

Re: Heat risers, how are they supposed to work?

I removed the Butterfly flap and never looked back.

[Patrick H.]

Re: Heat risers, how are they supposed to work?

I have found that the reproduction ones will bind and freeze closed after a while.
Some of them bind up when brand new.

As a result, I have purchased some NOS ones which in my case have worked well.

[Michael J.]

Re: Heat risers, how are they supposed to work?

Thanks Joe, that is exactly as I have expected they would work. And why I was so frustrated when the temp gauge says 190 and it has been running for an hour and it is still closed at idle.

[Owen L.]

Re: Heat risers, how are they supposed to work?

I have found that the reproduction ones will bind and freeze closed after a while.
Some of them bind up when brand new.

As a result, I have purchased some NOS ones which in my case have worked well.

[Dan B.]

Re: Heat risers, how are they supposed to work?

Here's a GM one I modified. Flapper removed, shaft, weight, and spring are still in place and appear and move as normal when installed.
Heat problem solved, and original appearance is maintained.


Heat riser w safety wire.jpg

[Timothy B.]

Re: Heat risers, how are they supposed to work?

Owen,

I think there would be a huge restriction in the exhaust path for the cylinders on the passenger side of the engine and the restriction would cause loss of engine rpm speed.

[John D.]

Re: Heat risers, how are they supposed to work?

Wiring the riser open was one of the biggest improvements in driveability in over 30 years of ownership. No sputtering out the RH exhaust and no more hot start problems due to fuel percolation. I dont drive the car in freezing temps.

[Mark F.]

Re: Heat risers, how are they supposed to work?

When I installed my undercar chambered exhaust system, I simply pulled everything out from the exhaust manifolds back (keeping all of it for potential future judging events) and installed a 2" (or 2-1/2" ?) free-flow spacer in place of the heat riser.

This was back in 2004, so I don't exactly remember, but I think I got it from LIC at the time (both Corvette Central and ZIP have ones listed on their websites).

Nothing at all in the exhaust gas stream to disturb right-side free-flow compared to left-side flow.
Nice, even, balanced sound and tailpipe pressures on both sides...

[Gary B.]

Re: Heat risers, how are they supposed to work?

Here's a GM one I modified. Flapper removed, shaft, weight, and spring are still in place and appear and move as normal when installed.
Heat problem solved, and original appearance is maintained.

Dan,

How did you eliminate the flapper? With something like a Dremel cutoff wheel?

Gary

[Dan B.]

Re: Heat risers, how are they supposed to work?

Gary,
Yes a Dremel with a cut off wheel, open the butterfly then you can cut the spot welds. I cross drilled the shaft inner side and used aviation SS safety wire to keep the shaft and related parts attached.

[Gary B.]

Re: Heat risers, how are they supposed to work?

Thanks Dan. Good job.

Gary

[Gary B.]

Re: Heat risers, how are they supposed to work?

Dan,

With the butterfly flapper removed, is the shaft then free to come out? Is that why drilling the shaft and adding the SS wire was needed?

Gary

[Larry M.]

Re: Heat risers, how are they supposed to work?

Dan,

With the butterfly flapper removed, is the shaft then free to come out? Is that why drilling the shaft and adding the SS wire was needed?

Gary

Yes........

Larry

[Dan B.]

Re: Heat risers, how are they supposed to work?

Dan,

With the butterfly flapper removed, is the shaft then free to come out? Is that why drilling the shaft and adding the SS wire was needed?

Gary

Gary,

Yes, this would prevent the shaft from "walking" out. If you decide to do this, allow 1/8" spacing between the wire and the inner body of the valve for expansion if you want the weight to be able to move freely when the spring opens.

[Brian E.]

Re: Heat risers, how are they supposed to work?

I know this is not a new/recent thread but is there any chance you guys can post some pix of your solution(s) to help those who can't quite picture what you're talking about (me)??? Thanks.