The Stovebolt Site Forums The Shop Area General Truck Talk Heat Riser Question

Hello Stovebolters,

Quick question - With the heat riser spring removed, does the counter balance on the heat riser valve weight the valve in the open or closed position? The valve on my manifold rotates freely.
Thanks!!!

There is no open or closed position. In the normal position (where yours is sitting with no spring)exhaust is deflected toward the bottom of the intake manifold. In normal operation the spring heats and moves the flapper to send the exhaust directly out the pipe. Both positions are open as far as exhaust flow is concerned.

I know, the terminology is confusing to me. So what I mean to ask is: with the spring removed, is the flapper inside the exhaust manifold allowing heat into the intake manifold for warm-up proceedure (cold engine) or is it in the position to route all of the heat into the exhaust (hot engine).

Thanks for your very quick answer to my question cletis!

cletis is right all though when the engine is warm the "Valve" is considered to be open. The weight will be at the lower position (open) when it is free to do so. The by-metal spring will overcome the weight when cold and "close" the valve. In either case the exhaust remains open. The exhaust air is simply deflected to the bottom of the carb. when cold.

With the spring expanding when warm - the exhaust bypasses the intake pipe.

So without a spring there its always bypassing the intake, as only a cold spring will redirect the exhaust upwards...

A quick look inside the shop manual illustration would also confirm this.

Thanks Everyone for the replies! I have a much better understanding of the heat riser now thanks to you all.
Much Obliged!