Fixing heat riser

[Redmond49]

I was reading through the tech topics this week and started reading the heat riser article. I didn't recall seeing that particular contraption in my engine compartment, so I went looking and discovered all the bits are simply missing from the manifold- the stop stud is there, and the valve is still inside the manifold rattling about, but the pin is broken off where it exits the manifold and the counterbalance and spring are gone.  So I've ordered a heat riser repair kit from Bernbaum's. The instructions in the Resources say the shop manual has procedures for installing/removing the manifold, but I can't find any such procedures in mine (the 46-54 Service Manual). Page 130 and 131 briefly cover the heat riser and manifolds. If there is any additional wisdom to supplement the tech article, please share! I expect I will start pulling things apart at some point this weekend. At the least I'll be soaking nuts and bolts in liquid wrench.

Edited January 4, 2014 by Tyson

[greg g]

The exhaust and intake manifolds are bolted together through the heat riser assembly.  There are 13 fasteners that attach the manifolds tot he block.  All the fasteners need to be removed, so make sure you have all 13 loosened or removed before attempting to separate the manifolds from the block as horsing on them might cause damage.  Then the 4 bolts going up through the exhaust need to removed to separate the intake from the exhaust, Invariable you will likely break most or all of them as they are threaded intot he cast iron of the intake. Just a fact of life for these bolts.  Make sure you take pictures and or label which studs have the oval brass washers so they can be reinstalled on the same studs for reassembly.  

 

When I had mine apart, I welded the exhaust flap in the horizontal position and welded the stud tot he casting also.  I have driven my set up in temps as low as the 20's with no drive ability issues noted. 

[Don Coatney]

This might or might not help.

 

http://p15-d24.com/topic/35101-factory-manifold-installation/#entry356064

[_shel_ny]

Lower the coolant level first. Get it lower than the manifold studs. Coolant may come out if a manifold mounting stud comes out rather than the nut just coming off. Some studs go into the water jacket.

 

#13 centered under the manifolds will be the most elusive.

 

Intake and exhaust manifold must come off together, and as Greg said, separate them after removal by taking out the 4 bolts. They can not be removed individually because they overlap slightly.

 

When reinstalling it has been suggested to leave the 4 intake to exhaust bolts slightly loose until the manifolds are snugged to the block/gaskets to get a good even fit. Someone once posted that they sanded, or planed the manifolds to get them even against the gaskets. seems that tightening the 4 bolts last could eliminate such an undertaking.

[james curl]

I have used an impact electric drill and a impact tool set on low to vibrate the bolts in the intake manifold breaking the rust bond loose before removing the four connecting bolts  Using this method I have been successful in removing the bolts in three different manifolds without breaking any of the bolts.

[Redmond49]

This is all very helpful. Shel, thanks for posting the procedures. Which service manual are those instructions from?

[_shel_ny]

That info is from a 1949-52 Dodge manual.

[55 Fargo]

I have a broken manifold on the bench, heat riser all intact and working. the exhaust manifold in truck, has heat riser seized in the warm position(not good in warm temps), the shaft is broken off, I have tried several times, to spin it forward, no such luck. Tomorrow picking up another manifold set, and will get ready to do the swap.....

[Redmond49]

I have another question on this...my exhaust manifold has been modified to dual exhaust, so there is an exhaust port brazed on in front of the heat riser valve and then the original exhaust port is behind the heat riser valve. The point of the heat riser is to direct heat up to the carburetor, but the amount of heat going there once I fix the valve will probably be quite a bit less than designed since there is a the second exhaust port in front of the valve. The exhaust output is noticeably uneven, so I'm guessing that the valve is still in there, but I guess I will find out when I pull it apart. The little axle is definitely still there and rattles.

[Don Coatney]

I also have dual exhaust ports in my manifold. The heat riser plate inside my manifold has been welded thus giving my manifold a true split. This also directs hot gas to my intake manifold full time. But I also have dual carburetors so the hot gas going to the intake manifold has no effect as there is no longer a carburetor located in the original position on the intake manifold.

 

I wonder if your heat riser has also been welded in place?