Heat Riser - Free or Keep Frozen?

[Barry S]

My heat riser was really stuck as well, but in the closed position. This is while the manifold is on the car, going through heat and cold cycles. I soaked it repeatedly with PB Blaster, and also purchased Mopar Rust Penetrant based on comments of folks on this forum. It wouldn't budge. I finally got it to move when I got frustrated and really leaned into it. It moved just a bit at first, but after working back and forth a bunch it finally freed up. You can leave it as is on your car since it's frozen open and it'll only affect cold weather start performance, but if you keep at it you might get yours to free up.

 

[Snotty]

If you were in California I'd say to take it to a muffler man and have it removed; not needed. But your weather is a lot colder than ours.

I had the ones on my '62 New Yorker, '79 Cordoba, and my current Newport all removed and the holes welded shut.

Not on the Cordoba though, now that I thought about it; it needed to pass visual inspection ever other year. My muffler guy welded a large flat washer on the inside of the heat riser so the outside arm would still move. He even kept the vacuum line attached to it. It passed Smog!!

 

[cbarge]

Mine was stuck closed when I bought the manifold.
So I knocked out the butterfly and left the shaft since it was not leaking.
With an electric choke,blocked off exhaust passages under the carb and not winter driven I did not NEED it anyways

 

[commando1]

How does a stuck heat riser warrant 23 posts?....

 

[The Goose]

How does a stuck heat riser warrant 23 posts?....

Because nobody posted “ isn’t that the flapper deal you’re supposed to knock out of there with a pipe...”

 

[cbarge]

How does a stuck heat riser warrant 23 posts?....

 

[Samplingman]

How does a stuck heat riser warrant 23 posts?....

Oh gosh, I thought it was because I posted the question....

Thank you all for your help! I will leave it as is so it looks visually original!

 

[Jim Kolenovsky]

For this much trouble I think I would go to headers. Not have to worry about exhaust gases stumbling over each other. Improve exhaust out flow and gain a little horsepower to boot.

 

[polara71]

For this much trouble I think I would go to headers. Not have to worry about exhaust gases stumbling over each other. Improve exhaust out flow and gain a little horsepower to boot.

Excessive heat, exhaust leaks, fried starters, hot floor. NO!

 

[Jim Kolenovsky]

Excessive heat only if you do not wrap it, you have the same amount of heat with old system and not insulating. Exhaust leaks, happen with poor gaskets and incorrect bolts, non-locking bolts. Fried starters , there is insulation wraps for the starter and starters do get fried from the old exhaust systems. Hot floor boards, been around as long as exhausts have run under them, that is why we have been using sound deadener/ heat reflector when we redo the interiors of our vehicles. There are fix's for all problems if you want to solve them.

 

[polara71]

Excessive heat only if you do not wrap it, you have the same amount of heat with old system and not insulating. Exhaust leaks, happen with poor gaskets and incorrect bolts, non-locking bolts. Fried starters , there is insulation wraps for the starter and starters do get fried from the old exhaust systems. Hot floor boards, been around as long as exhausts have run under them, that is why we have been using sound deadener/ heat reflector when we redo the interiors of our vehicles. There are fix's for all problems if you want to solve them.

So I have to fix problems created by installing headers that I don't have if I keep the HPs?
That is certainly foolish, creating problems for no benefit. No thanks.

 

[WSP]

I spent weeks putting different oils and and bolt looseners on mine till free.
Then had an exhaust leak...

 

[mr. fix it]

Can’t say that I have tried this but isn’t this just another method of heat and quench to dissolve the rust that has built up?
I have used heat and oil spray to do the exact thing.
Not trying to be difficult about this trick but just saying that there’s a similar method available

 

[Jim Kolenovsky]

So I have to fix problems created by installing headers that I don't have if I keep the HPs?
That is certainly foolish, creating problems for no benefit. No thanks.

You have to deal with the same heat, gasket problems, etc. anyway . If you have a friend with a thermal gun and have them take a picture (shoot) of the heat coming off your exhaust. As for the floors you feel the heat coming up through the carpet due to exhaust heat. The only way to combat the heat we are talking about is to insulate everything.

 

[polara71]

You have to deal with the same heat, gasket problems, etc. anyway . If you have a friend with a thermal gun and have them take a picture (shoot) of the heat coming off your exhaust. As for the floors you feel the heat coming up through the carpet due to exhaust heat. The only way to combat the heat we are talking about is to insulate everything.

I can't expel any more thought on it than what I have. Those are the reasons, like it or not.

 

[65sporty]

I would leave it alone because I hate exhaust leaks. If I wanted to do something with I would remove it and weld it shut.

 

[owen martin]

I’m in the same situation as you with the heat riser on my 67 Monaco 500 and would like to eliminate it with a new one without the heat riser or headers! The problem is I’m Leary of headers from previous experience with headers years ago as they kept leaking as the head bolts kept loosening and finally the headers rusted out at the collector... what are the new ones of today like? Or are there manifolds without the heat riser?

 

[twostick]

I suggest a few days drenching it with a 50/50 solution of ATF and Acetone and then determine if going further is opening a Pandoras Box.

^^^^^^
This.

Unless you are looking to wring the last horsepower out of it, a functioning valve and crossover is actually good for fuel mileage.

Kevin

 

[70bigblockdodge]

Almost to a third page. Keep it up.

Unless you are looking to wring the last horsepower out of it, a functioning valve and crossover is actually good for fuel mileage

Have to disagree with that. Power and therefore efficiency is at its best when constantly corrected or consistent numbers. So your target is ~14.7 pounds of air to 1 pound of air at cruise. Air gets its weight from the total of the molecules, but being a gas it expands and contracts a large amount. Hot air the molecules are farther apart causing the need to open the throttle further to get the needed molecules to reach the target A/F ratio to burn the X amount of gasoline to move the car. The heat crossover is very inconsistent heat source and works counterproductive of load percent. Everytime you push down on the pedal the exhaust gas temp goes up increasing the heat in the intake which in turn heats the incoming charge and expands the distance between the oxygen molecules at the time when you need more to supply the increased demand for fuel that is needed to do more work. It is a cold start/cold weather drivability item only. If it worked to increase efficiency and mileage they would still be using exhaust heat and egr valves in new cars, they don't. Today's gasoline no longer has a surface tensioner added to it the reduce evaporation (thanks to closed fuel systems), so it atomizes much more easily, also reducing the need for the heat crossover. Of your car is a fair weather driver and rarely sees operation below 50°f there is literally no need for it. Would I take a working engine apart to block it, no. Would I block it on a engine that is going back together, yes.

 

[Snotty]

I’m in the same situation as you with the heat riser on my 67 Monaco 500 and would like to eliminate it with a new one without the heat riser or headers! The problem is I’m Leary of headers from previous experience with headers years ago as they kept leaking as the head bolts kept loosening and finally the headers rusted out at the collector... what are the new ones of today like? Or are there manifolds without the heat riser?

Not necessary to find a new manifold. If you have a good exhaust man, he can remove the riser and weld the holes on your manifold. No problemo!!

I've had it done twice; sorry I don't have a picture.

Actually, three times, but one left the valve in place.