Heat Manifold Operation

[p10plymouth]

I read the article in the technical section... but am not sure its @ 53 degrees here and I ran my car @ 25 -1/2 hour ,I notice that the snap of my excelaration the weight moves to the 3 oclock position , partial throttle does not open as much... When it gets hotter will the spring make the weight open completly to the 3 oclock postion or will it allways want to snap back to the 12: oclock postion thanks for letting me know.. I this is on my P10 1940 plymouth

[TodFitch]

On my car when the manifold is well and truly heated up (summer after a long enough drive) the counterweight is at the 3:00 o'clock position when the engine is idling.

[Jim Saraceno]

I thought I had read in a manual that when the manifold was cold, the heat riser was closed. When the manifold is hot, the heat riser will open on acceleration.

That is to say, the spring will hold it closed, but it won't hold it open.

That's the way mine works.

[Plymouthy Adams]

the spring is intended to hold it open thus diverting the heat to warm up the chamber in the manifold to help atomization of fuel droplets..(the spring is not so strong that when revved the exhaust gasses are allowed to escape 1/4 turn snap movement) as it warms the bi-metal spring on the butterfly valve it loses this spring tension and allows full flow. This is not that critcal except to say you do not want it rusted in any position unless it is (closed).So if your valve is free and flops without binding regardless of the springs bi-metal properties..it will be forced to the proper position when the engine speed is raised due to increased gas flow.

[p10plymouth]

So is it safe to say it will mostly snap back until its really really hot.. and safe to say 1/2 hour of idling it more than likely will be in the 12 O'Clock position..( but moving on throttle snap)

[Normspeed]

Want to wind some springs here, say "toy car".

DOH! Why you little......

[p10plymouth]

Today it went to 75 degrees so out for a test drive 4 miles from home ... at a red light engine felt like someone was cloging the exhaust . If I revved it up it would go... Got home and still the metal weight was not opened but on slight throttle it would open ... well enough of that ... made the weight hang in the open position and took the spring off (put it on the other side .. ) i redrove 8 miles perrfect ,Stays open and going to stay that way.. a old time guy said to me 15-20 min that it should of stayed open period not go back.. O well ... I drive it spring summer . I can wait till it warms up .. just wanted you to know..

[p10plymouth]

I found the problem ... and can only share the experience , hopefully it does not happen to any one else... I bought a "NEW " heat riser kit when I was doing my engine compartment... I installed it and all should of worked .... Turns out the part I got was for 1955 and up(mine is a 40 Ply) and the shaft is to long. Which means the spring is 3/8 to 1/2 away from the manifold and the metal wieght is Evan further away! so no heat can transfer quick enough ... moral of story make sure you find the right parts (and person selling them) I need a way of slitting the shaft I tried my dermal its too wide and awkward .... Does any body have a suggestions I need to at least go 1/2 inch , in toward the manifold and reslit the shaft. (hopefully not take it apart to do that..)THANKS

[Plymouthy Adams]

jewelers saw...

[Tom Skinner]

I used a small Hack Saw Blade loose out of the Saw.

Go slow and do not cut to deep into shaft, it wil go fast.

Tom