Heater Riser Fitment

[The_Eagles’_Nest]

So when reading the receipts of what has been done to my Imperial, a previous shop noticed that the heat riser valve was “worn out”. This shop installed a full exhaust which has since been replaced, again. They noted the heat riser was “worn out”. When I removed the y-pipe to reseal my oil pan, I saw the heat riser was beyond worn out, it was just plain missing.

I see there are repair kits available, but they note HP applications. So will that kit work on a standard 440 manifold as well, not just the HP manifold?

 

[CBODY67]

The issue might be the diameter of the manifold exit, which relates to the diameter of the flapper valve of the heat riser valve.

On our '66 Newport 383, the heat riser had "stuck" at the 1/2 place. No performance issues, which probably might have helped the exh crossover passage in the intake manifold stay open.

At one of the maintenance checks at the dealership, I asked them to free it up, which they did, dousing it with the Mopar Heat Riser Lube (penetrating oil with a slight amount of graphite in it). It worked freely for a while, but eventually stuck again.

Several years later, I asked about a replacement. They got the Chrysler service kit and installed it. I noticed that the shaft did not move freely, so the tech got a reamer, put it on an air drill, and reamed it to size. THEN the shaft went in easily and freely turned. SO if you get a Chrysler NOS kit, check and adjust this during installation. BUT as good as the installation was, the valve again "stuck" at the same 1/2 open place. In our temperate N TX climate, even in the winter, I could tell no difference in performance. Cold or hot.

It might be hidden by the counterweight, but the flapper valve's shaft runs in a brass/bronze bushing which is tapped into the exhaust manifold. That is a "wear interface", so it can be removed and a new one installed in its place. When replaced, by observation, the inner diameter of the bushing needs to be fine-tuned to the outer diameter of the shaft which runs in it. Just good installation practices.

I'm not sure how "worn out" describes a stuck heat riser valve, UNLESS they were seeking to sell something. FWIW

Just some experiences and observations,
CBODY67

 

[The_Eagles’_Nest]

It runs like a cammed out race engine for 5 minutes or so then the idle picks up like normal. I’m not concerned about anything expect the diameter of the valve. I can do most everything myself and know someone who can do what I can’t.