The Stovebolt Site Forums The Shop Area Engine Shop Heat riser valve 1957 235 engine

Hellol everyone just hoping for some good advice,
The spring in my heat riser valve is missing and the little stud that braces the spring above the heat riser valve is maybe 3/16 long. It seems to me that it might have been broken off along the way somewhere or is that how long that little brace is supposed to be?
How would you go about fixing that? Also, is the valve open when flipped toward the motor or is that the closed position?

Thank you kindly

Wade V
1953 3100

Wade - Give this "blast from the past" thread about the Heat Riser Valve a thorough reading. Lots of great info and pictures to explain how everything works.

"3/16" is a tad short on that spring retention pin. Not sure how you might fix that, but others should be along soon to offer suggestions and more help.

Dan- Thank you Sir

Stovebolt heat riser springs are all over Ebay for about $30.00 apiece. This one works just as well for a fraction of the cost:

www.ebay.com/itm/182196172425?

Jerry

Also, the usual suspects have the spring for around $20. (Jim Carter, Chevs of the 40s, The Filling Station,...) I think I got mine from Jim Carter.

My spring was broken, shaft rotted in two. Holes in the manifold were egged. I happened to have an old bbq grill that I kept the stainless grid with a diameter just a smidge too big. Cut a piece a little longer than original.Drilled out the cast manifold to fit and turn freely. the flap had to be drilled just enough to also fit the rod as well. Drilled for the flap for a tiny stainless nut and screw from my mayonnaise jar of who knows where it came from keeper stuff. used the original to get the distance from the weight to center of flap. Dry fit installed in manifold to get the right angle for the weight to drop to make the flap default to open. Marked that location and took apart to drill for a small cotter pin to hold the weight on. Reinstalled to get the angle of the slot to hacksaw into the other end for the spring. Held the weight up to closed position, eyeballed install position of the spring, (purchased from Carter) gave it a tiny bit more to put a little tension on the spring.I had cut 1/8 “ extra length so the slot was longer and no risk of spring falling off. Installed everything permanently, tapped threads of screw in flapper into a rivet. Pinched the end of the slot with vice grips to trap the spring. Bench tested with a couple of quick flashes from my propane torch. Weight dropped, flap opened and it’s amazing how much movement is in that spring. Yay! As for the stob that catches the spring you might look a small diameter of steel tubing to slip over and drill for a tiny picture frame finish nail for a rivet. Originally I don’t know if they are threaded or just pressed in and to do it right that’s probably the correct way. One of the exhaust pipe studs was broken off so while I had it all apart on the bench I drilled out and chased the threads, installed new studs,replaced rusty nuts with new extra deep brass nuts. Good to go.

Larry, you didn't happen to take any pictures ? Sound like a nice repair on your heat riser. My heat riser is wired open at the moment, being in the South it's not really a problem.

Which way is open?

When looking at the heat riser weight from the front of the engine, is it all the way counter-clockwise or all the way clockwise?

Correction, it wired closed, I was thinking about it in the wrong direction.. I wired the flap closed while I had the manifold off last fall. The counter weight is missing from my assembly, appears to have been gone for a long while.

Which way is closed?

And does "closed" mean that zero exhaust heat is directed to the intake?

Otto - Those questions were already answered in this Heat Riser Valve thread I posted above in reply to Wade's original question.

Thanks

Craig, the first pic is spring cold, weight pulled up into the closed flap position. #2 is spring warm expanded allowing weight to drop counterclockwise as you are looking at it to open flap position. #3 is backside and spring.

Might be a good time to review terms of reference and Heat Control Valve orientation.

See Figure 3 in Manifold Heat Riser and Heat Control Valve. In Figure 3, the left drawing shows the Heat Control Valve "open." The right drawing shows the Heat Control Valve "closed."

Cold Engine. When the Heat Control Valve is Open, hot exhaust gas is redirected to circulate around the intake manifold and the base of the carburetor before exiting the exhaust manifold and header down pipe.

Engine at Operating Temperature. When the Heat Control Valve is Closed, hot exhaust gas flows directly to the exhaust manifold and header down pipe; blocked from circulating around the intake manifold and base of the carburetor.