heat riser question

[bosworth]

The heat riser is frozen on my early 49 p15 Plymouth club coup. I believe that the engine is a 50 dodge 230. What remains is the valve shaft and the stop stud. If the valve is in the open position I will put the heat riser project on the back burner, but if closed i think I should address it sooner. The shaft has a split in it for the spring, the split is orientated at about 2 and 8 o'clock position, does that give a clue as to the position of the valve? I will continue to shoot it with PB blaster on hopes that I can work it free.

As always thanks for your help

Bill

[greg g]

Fully clockwise it the position that directs the flow out most directly.

[_shel_ny]

2 and 8 would be the full open-heat to the carb-position

[hendo0601]

Not to hijack this at all, but is the heat riser really needed on these flatties? On v8s I always just cut the heat riser out or weld the flap in the wide open position. After reading about aftermarket intakes and headers for these, carb heat seems to be a pretty big deal, but for the stock intake/carb how vital is it? I was going to gut the heat riser out of my chrysler as it is frozen shut but I wanted to ask before I go that route.

[_shel_ny]

Not to hijack this at all, but is the heat riser really needed on these flatties? On v8s I always just cut the heat riser out or weld the flap in the wide open position. After reading about aftermarket intakes and headers for these, carb heat seems to be a pretty big deal, but for the stock intake/carb how vital is it? I was going to gut the heat riser out of my chrysler as it is frozen shut but I wanted to ask before I go that route.

 

 

Have been some posts on that here. Seems most feel that it is not needed. Some have blocked off, or welded the flap in the "closed" position.

 

Edit: or even wired the counterweight in the full clockwise position for lack of a spring. (not me)

Edited October 31, 2013 by shel_ny

[captden29]

I have 2 cars with them. one is frozen closed, the other I have blocked to closed. I think they are not needed. capt den

[Merle Coggins]

Here is a good article about heat risers written by one of our former members, Dave Erb, (aka Greybeard)

http://dodgepilothouseclub.org/know/riser/riser.htm

[TodFitch]

They are the most good for cold start drivability when it is damp out and the temperature is a bit above freezing. If you don't drive your car at times like that then you probably won't notice the difference.

 

Personally, I find it makes a pretty big improvement where I live from about now through March. Your climate may be different.

[hendo0601]

Since we just picked this car up a few months ago I havent really had much time to get it absolutely roadworthy...not all of the lights work, the front tires were installed in 1957 so they are scary as hell, and the driver's side windshield wiper doesnt work.....and up here in the extremely rainy pacific northwest all of those things are vital for driving through the winter, so I am not too concerned with cold weather starts. I will probably just yank the manifold and cut it out and weld the hinge holes closed just to be done with it. Thanks for all of the feedback!!

[bosworth]

Well that sure answers my next question, I will not rebuild the heat riser, but I do have to get it open. I'll continue to try to rotate the shaft but in the next few minutes I think I'll order new gaskets!

Thanks again everyone

Bill

[greg g]

I have mine welded and I have a thin stainless steel plate along with the gasket completely sealing the connection to the intake  manifold.  A piece of copper or brass sheet would probably work just as well and be a better gasket.  I have a Fenton cast intake.  I do run my heater return line attached to the intake, so it gets some heat when the car is warmed up and the heater is on.  I do drive occasionally in temps in the 30's and have not noticed any problems with starting or running with the choke partially out.  For a vehicle used only occasionally in cold weather I do not thing the heat riser is necessary, If you live in areas where your car would be used on a daily basis in freezing or sub freezing conditions I would probably rebuild the riser or provide some other source of heat.  

 

Has anyone ever had a situation where the Venturi Effect of air passing through the carb has cause frost to build up on the out side of the base of the carb??  I had this situatioin on a Honda I used for Ice Racing.  With the exhaust on the opposite side of the head the carb /intake got no heat and since it was operating at wide open throttle during races, that carb would actually build ice on the inside and outside of the carb.  Plumbing hot air from the inside of the car to the air cleaner ended that problem.

[hendo0601]

Many years ago when i lived in the northeast I had a slant 6 car with a Clifford 4bbl intake on it and a pair of headers...While driving during the winter the whole outside of the intake runners would freeze over and cause carb icing...it was a pain in the butt. I had to stop driving it in the winter because nothing I tried would keep the fuel from freezing.

[Don Coatney]

In Vietnam I was working on a small flathead 6 powered roller used in the construction of roads. This engine had an updraft carburetor that failed with  no parts or replacement available. I fabbed up a "U" shaped hunk of pipe and converted the engine to a downdraft carburetor thus moving the carburetor away from the exhaust manifold heat. Upon first start-up the engine ran great for about ten minutes. This was during the very hot monsoon season with ambient tenperatures in the high 90's with humidity to match. After about 10 minutes the U shaped carb adaptor turned into an ice ball both externally and internally soon starving the engine of the air/fuel mixture.

 

There is a reason airplanes have a carb heat feature. Follow this link for some interesting reading.

 

http://www.donmaxwell.com/publications/MAPA_TEXT/Carb%20Heat%20Maintenance/CARB_HEAT_CARE.HTM

[Niel Hoback]

 Between 35 and 50 degrees in humid weather, the entire throttle casting will get a coat of ice a good 1/8" thick.  The heat flap works well and there are no performance problems because of it, but it is something to see covered in solid ice.