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1937 Dodge Heat Riser Trouble...


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post-76327-143141878526_thumb.jpgMy '37 Dodge D-5 motor has a stuck heat riser just below the carb- I don't think it has ever been serviced. Does anyone have a pamphlet or tips on how best to free it up- my guess is that it is stuck in the closed position.

I have a 1/4" tube sticking straight down below the spring that drips a tiny bit of gasoline when the motor is turned off- I have no idea if that is original?

Thanks,

Jim

Edited by fozz71 (see edit history)
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That tube is a fuel drain tube which is original and drains excess fuel from the carb in case of flooding or over expansion of heated fuel. The butterfly valve must operate freely for the engine to perform correctly. Best thing is to remove the manifolds from the engine. Remove the four bolts that hold the 2 parts together and carefully separate the unit. There is an asbestos clad metal gasket between the 2 parts that will have to be replaced; this is available new. Remove the counterweight and spring . Now you'll have access to the valve. If the valve moves at all you have a good chance of getting it free. I don't remember if the butterfly is riveted to the shaft or not. If it looks like you can't get it apart don't try! You don't want to break it. Soak it with WD-40 or some other good penetrating oil for a while . Try working it back and forth until it frees up. It must be really easy to move for it to operate. If the butterfly is damaged or rusted away it will have to be replaced. According to the parts book, there were servicable parts available so it should come apart if needed. After you get it freed and reassembled( I used stainless bolts) , replace the heat spring with a new unit ( available from the Mopar parts suppliers). Your maintenance manual will show you how the spring is installed. Incidently, that tube drain tube should extend down through the engine splash shields.

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Thanks jpage- for the excellent service help! I really appreciate that time you took to help me. If I remove my manifolds- are the manifold gaskets available through suppliers? I'll want to add new ones all around.

I only drive my car in warm and nice weather so is that butterfly absolutely necessary? If I find it to be rusted solid- can I do without it? Naturally I'll try and salvage it- but just in case?

Thanks,

Jim

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Thanks jpage- for the excellent service help! I really appreciate that time you took to help me. If I remove my manifolds- are the manifold gaskets available through suppliers? I'll want to add new ones all around.

I only drive my car in warm and nice weather so is that butterfly absolutely necessary? If I find it to be rusted solid- can I do without it? Naturally I'll try and salvage it- but just in case?

Thanks,

Jim

Your valve is in the cold position (it rotates clockwise down when the spring gets warm). So you will likely have some drivability issues in warm weather with it in the position it is currently in.

Manifold gasket set is Chrysler number 780460. You can cross that with NAPA online to their number. I believe you will find that crosses to the following:

CarQuest MS18005

NAPA FPG MS8009B

Best Gasket 11004

Original early '30s part number for the gasket between the intake and exhaust was 601420 which should be NAPA FPG 8011.

That drain tube fitting is supposed to have a one-way check ball in it. When you have the manifold apart you might want to check that it is still functioning. If it is stuck open then you will have a vacuum leak affecting you mixture.

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ply33,

Thanks for the cross-referencing numbers and the advice, plus I was wondering about that tube; I had suspected that it was a vacuum leak and something was probably not configured correctly. I'll rip it apart and see if I have a check-ball in it yet.

Thanks for this great advice! You guys are great and invaluable!!!

Jim

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The attached photos may help you see what's going on inside. This heat riser is in the same location as yours. It is in the "cold" position. If left in this position the bottom of the carb will get over heated causing rather severe running issues.

If you separate the manifolds to loosen the riser valve, do not resurface the faces of the square opening. Just use a new gasket. If resurfaced, the two manifolds' bolt holes may not correctly align with the studs in the block.

As in the last photo, once the two manifolds are put back together, check the faces of the manifold for square and have them resurfaced if necessary while they are still off the block.

post-67404-143141880767_thumb.jpg

The fuel drain should also, optimally, be vertical. Looks like it was screwed into the manifold a bit too far.

post-67404-143141880737_thumb.jpg

post-67404-143141880754_thumb.jpg

Edited by 1936 D2 (see edit history)
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Be carefull when removing the brass drain fitting. The outer rim of the hole for the tube is rather thin and if it's really tight in the manifold you can damage it if the wrench slides on the flats. Also try to avoid breaking it ;they are hard to find. I did forget about the ball and Ply33 is right ,it must operate correctly. The original drain tubes have a slight angle bend near the top so that the tube extends through the hole in the splash apron. That's why the drain fitting is angled in that manor. By the way, does anyone know the current Fel-Pro, Victor or NAPA number on the exhaust pipe flange gasket for '36 Dodge? I need one!

Edited by jpage (see edit history)
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Be carefull when removing the brass drain fitting. The outer rim of the hole for the tube is rather thin and if it's really tight in the manifold you can damage it if the wrench slides on the flats. Also try to avoid breaking it ;they are hard to find. I did forget about the ball and Ply33 is right ,it must operate correctly. The original drain tubes have a slight angle bend near the top so that the tube extends through the hole in the splash apron. That's why the drain fitting is angled in that manor. By the way, does anyone know the current Fel-Pro, Victor or NAPA number on the exhaust pipe flange gasket for '36 Dodge? I need one!

Having damaged a bunch of brass fittings in the learning process, I always thread in a spare tube nut before putting a wrench on the flats.

Only have an obsolete cross for the '36 exhaust pipe flange gasket in my database, but the way I found the correct gasket for my '33 was to have the counter man at my "local better auto supply" match my tracing up with what they had in stock.

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Holy Smokes- I got the nuts all off the manifolds (got drenched- I didn't know the forward two bolts connected to the water jacket) and now the darned dbl-manifold is stuck to the block. If all nuts are off and the sucker is tightly froze to the block, and I don't want to damage anything, does anyone have a trick for freeing the surfaces? Thanks- Jim

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Looking at the photo again the valve appears to be in the open (cold position). Not good! As the engine heats up the spring looses tension and the counterweight pulls it closed so the exhaust bypasses the intake manifold.

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I was able to get the manifolds off the engine and even separated them- now just to free the shaft as it is frozen in the cold position and my rear bushing is frozen well, I have ATF puddled on it now and will let it sit tonight.

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