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Intake Manifold Thermo Coil?


Go to solution Solved by keithb7,

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Yesterday I took the carburator off the manifold again.


For the first time My brain registered a coil of metal on the square of metal between the intake and exhaust manifolds.


I have no idea what it is but my brain tells me it has to be some kind of thermo coil that opens and closes a door to heat up the intake manifold.


If that is what it is and it is seized open it would help explain my Fuel flow/vapor lock issues.


What is this thing,  Could it cause fuel boil, and what is the best way to "un-seize" it?

Manifold thermo coil.jpg

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That is exactly what I was thinking it was! 


It wasnt "Seized" but it was really tight.  I sprayed it down with WD40 and used a screwdriver to move the weight back and forth.


It moves, but not nearly as freely as yours. I am going to do a couple sessions and hope to free it up,  But I cant get to the back pivot point with the engine assembled.


If I cant get it freed up,  Ill order some intake/exhaust gaskets. Clean up and repaint the manifolds while they are off the car.  I had already planned to do so but this kind of kicks it up the priority pole.



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After watching your video again, and then working the weight on my heat diverter,  I think My "flap" has come off the axel. like yours.


Your "after" shoots showed about 90 degrees of rotation, Mine is giving closer to 200 degrees (more than 180 degrees anyways).

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Good news is that heat riser kits are available.  Bad news is you have to take the exhaust manifold off to fix it.


Worse news, if you mangle the manifold our buddy MoParPro has ones, for $900 a pop.  I will never buy anything from him.  I will learn to weld and build my own headers instead. Or just install the duals I have, lol.

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 Glad it helped you @OUTFXD

Re MoparPro: “Never” is not quite long enough. That guy…If I ever meet him at a show like Hershey, I’ll be known among the Mopar community for alot more than my silly little YT channel. 

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1 hour ago, OUTFXD said:

Anyone got a link for a good write up to remove the manifold(s)?


I don't know if this is a good write-up but it will give you some things to think about.  :)


By the way, I removed the manifold heater system, put a steel block-off plate between the manifolds.







Here is how I plugged the holes left in the manifold. The tab is plug welded to a bolt (think it is 5/16") that goes all the way through and plugs both holes left by the removed shaft.




Edited by Sam Buchanan
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So,  If I where to replace the gasket(between the manifolds) with a plate the size and thickness(of the gasket) and seal it with high heat RTB(and plug the holes accordingly). would that work?


Edited by OUTFXD
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  • 2 weeks later...

My head is exploding, but I think I figured out the heat riser valve, or flap.  I studied and re-studied Keith's video, and my own presently disassembled, um, assembly. 


We want the flap to be vertical when the engine is cold, to divert the exhaust to heat the intake manifold.  When hot, not - flap horizontal. 


The spring is counterintuitive.  I would think that when heated the spring would contract and pull something.  Just the opposite.


The counterweight tries to close the flap, for straight-through exhaust, but when the engine is cold the spring keeps the flap vertical.


When heated, the coils contract, but the effective length of the spring increases.  The spring allows the counterweight to close, allowing straight-through exhaust . 


That's my story and I'm sticking to it.  

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  • 3 weeks later...

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