'51 Super's frozen heat riser

[Kestrel]

Anyone know of a source for manifold heat riser shafts or components ? Mine is frozen fast . A month of daily penetrant doses and banging with a hammer did nothing. I'm afraid the drill might have to come out.

 

I though maybe someone has made them up as did someone did  for my '32 Chevy which had the same problem.

 

Now don't be laughing at my shop crane helping with the removal. I work alone and just recovered from an injured back.....and not getting any younger.  

 

[NTX5467]

Nice machinery!!

 

Unless you're needing the heat riser for cold weather operation, if the picture is where it is "stuck", it might be best to leave it where it is.  It's obviously found where it wants to be positioned.  In our later model cars where I had the valve replaced AND knurled the bronze bushings the shaft went through, having the working valve might have had some "mental" benefit, but no real benefit in how the engine warmed up or ran in cold weather.  An inline 8 might be different than a "bent" 8, though.

 

When you do get the new valve and install the bronze bushings the shaft goes into, make sure the shaft turns easily in those bushings!  Not "tight", but "easy to turn" without being too loose.  Might need to reem the bushings' ID for extra clearance.

 

Just some observations,

NTX5467

[Bloo]

IMHO soak it up in some real heat riser solvent (Mopar 4318039AC) for a day, and then heat up that shaft from the inside with an acetylene torch. Let it cool off. When its cold again spray it some more, let soak, and then heat it again. Do this 2 or three times over the course of a day or 2 while you are working on other things. then try tapping it again from the outside.

[Kestrel]

Great tips on the bushing if I go that way. Meanwhile I'll break out my torch and give it a try. The OWNERS (and shop) manual says to lubricate every 1000 miles with graphited kerosene, and actually warns of a cracked manifold if the valve is stuck in on position due to constant excessive heat. Sure enough, it cracked but not at critical spot. I plan on driving the car in cooler weather so it would be nice to have it working. Its a long piece of steel, might like some help warming up, especially in New England.

 

I can't imagine too many owners ever lubed their riser. Thanks guys.

[old-tank]

13 hours ago, NTX5467 said:

Unless you're needing the heat riser for cold weather operation, if the picture is where it is "stuck", it might be best to leave it where it is.

Believe me you will never miss it!   i have eliminated the heat riser in all of mine with carburetors and they perform perfectly in temperatures a s low as 20* F.  The available fuel in winter is much more volatile than when these cars were contemporary.

[beerczar1976]

On ‎1‎/‎10‎/‎2019 at 6:39 AM, Bloo said:

IMHO soak it up in some real heat riser solvent (Mopar 4318039AC) for a day, and then heat up that shaft from the inside with an acetylene torch. Let it cool off. When its cold again spray it some more, let soak, and then heat it again. Do this 2 or three times over the course of a day or 2 while you are working on other things. then try tapping it again from the outside.

I agree with Bloo.  I used the AC-Delco version of the heat riser solvent off of Amazon.  Sure enough after a couple days of spraying and repeated tapping from both ends of the shaft, mine freed up.  You're probably in a better spot that me, as mine was still mounted on the car.  At least you'll be able to spray down the insides of the valve as well.  I basically spray some of the solvent on the shaft on the valve every so often now and work it back and forth to keep the bearings lubricated and freed up.

[Kestrel]

SUCCESS !!

 

See my last post under subject "Buick Manifold Gasket" this forum. Thanks Beerczar and others. 😅

[60FlatTop]

Right about 36 to 38 degrees F. is where that heat is needed. I am of that group that figures if GM could save $0.25 by not putting it in you never would have seen it.

 

I would drill it out and fix it. Option #2 would be to leave it alone and find something like this:

And just shorten the down pipe a bit.

Bernie

[fraso]

All gasoline engines work better with a heat riser system, which is designed to create a hot spot under the carburetor.  See Intake Manifold Heat.

 

The part about why the hot spot is necessary starts at 5:35 in the video.

 

 

[Kestrel]

Impressive animation for almost 85 years ago !

 

 Since mine has been brought back from the dead, I'll keep my valve maintained, functional, and the gas molecules happy. I've read it also prevents carburetor icing  which is more of a nuisance in our old cars and obviously not life threatening as in carbureted aircraft. 

[Bloo]

On 1/11/2019 at 2:44 PM, 60FlatTop said:

Option #2 would be to leave it alone and find something like this:

 

But that isn't going to work on most inline engines! Inline engine heat risers typically redirect flow up inside the intake/exhaust assembly, and the exhaust goes out the same hole whether hot or cold.

 

That trick works fine on V8s though.

[pont35cpe]

I have two Buick inline 8s I rebuilt, a `36 233 engine and a `41 dual carb 248, all three of the heat risers were froze in place. I first looked at the flapper and noticed it was closer to one side(all three), so instead of trying to turn the flapper, I applied pressure to the end of the shaft to move it sideways, that`s all it took, all three came loose. All three of the flappers of my manifolds have about a 3/32" sideways movement..

[60FlatTop]

That's right. It wouldn't work. Too many V8's in my life. V12's too.

[Beemon]

The heat riser valve eventually opens up and is out of operation. Speaking from a V8 perspective and having started and driven my car in the teens, I can that I have never had an issue in the absence of of the heat riser valve. I also have the heat track plugged at the carburetor mounting base, too. Modern gases are volatile enough in winter blends that it doesn't seem like a necessity to have one anymore. Of course I still tell everyone I'm late in the mornings because my carburetor iced over, but I can assure you it hasn't happened once.

 

Since it's the same gas going into the straight 8s as it is my V8, I'm going to go out on a limb and say you probably don't need one either. And realistically, are you driving this car below 38 degrees, like Bernie said? Most people drive only during the nicest parts of the year. At least it was stuck in the open position!

Edited January 17, 2019 by Beemon (see edit history)

[Ben Bruce aka First Born]

 

 Is it necessary?  Not really.  Does it HELP. Absolutely.  Remember, the engine is pulling a vacuum on the intake manifold right up to the throttle plates. This is what allows atmospheric  pressure to force gas into the manifold.  When the gas is introduced into the vacuum it cools. Some of it CAN drop out as liquid due to the cooling. This, in turn, can cause erratic performance.  The heat on the bottom of the intake from the exhaust helps prevent same.

 

  Ben

[old-tank]

Even with the valve open there is some heat at the bottom of the intake manifold...just not as much.  And with todays highly volatile fuel there is enough heat.  That valve has little or  no effect on carburetor icing; only warm air though the intake will solve that (hot air from the radiator after the thermostat opens or in later cars hot air off the exhaust manifold).

On one of mine I worked and worked to free it up and finally did.  It leaked exhaust in service (tick. tick. tick).  I had to remove the manifold, cut everything out and install some plugs where the shaft was.  Subsequent manifolds just had the valve cut out with no change in driveability.

I am all for restoring this old technology to work as designed, but sometime things need to be changed.