Heat Riser Confusion

[chucky07]

well the more I read about the heat riser on my exhaust manifold the more unclear i am...Maybe someone can help me figure it out..

First I know I can get a repair kit, I called then and Now Automotive and they manufacture them..for like 49 bux. I talked to the owner there and he basically confused me more..I told him I could not free the flap on my riser and he said "that can be a problem and you might break your manifold)....

So I stopped trying to free it..I know I'd never find another manifold here and I'm so close to starting my new engine and all.

Anyways..here is a picture of my heat riser and the position it is stuck in..

What is your guy's opinion on what I should do? Can i run it in this position without hurting the engine? Should I keep trying to remove it..Hammer it? etc..STill not clear on exactly the function of the heat riser..(on the split manifolds there is none at all that I can see.

any advice will be much appreciated as this is all I have left to do before i can fire her up..

thx in advance..

[Norm's Coupe]

I installed a new heat riser when I rebuilt my P15. My old heat riser was stuck like yours is. You can run the car like it is. Only problem being you may have to use the choke a little longer to keep the engine running smoothly until the car heats up to operating temperature.

That said. You can get that out without damaging the manifold like I did. I used a dremel tool with a cut off wheel to cut the old flapper out. Just cut the shaft on both ends of the flapper to remove the flapper. The shaft will probably still be frozen in the manifold though. Once the flapper and most of the shaft is out you can drill out the remaining ends of the shaft from the outside of the manifold. Just like removing a frozen screw or bolt, use a slightly smaller drill bit to do it with. Once it's all out, you can then install the new shaft and flapper that comes with the rebuild kit. You don't have to pound on the flapper with a hammer to get it out, so it won't break the manifold. Just make sure you drill straight.

[Merle Coggins]

With your manifolds split, like shown in your picture, you can do like I did. I used an oxy-acetelene tourch and gently heated the mating surfaces just over the shaft. I also had a Vice Grip clamped on the shaft, and when I got the manifold nice and red it came loose easily and has been free ever since.

A hand held propane tourch may work, but it may not get it hot enough. If you have access to an oxy-acetelene tourch, give that a try.

Heat where the arrows are pointing

Merle

[Norm's Coupe]

With your manifolds split, like shown in your picture, you can do like I did. I used an oxy-acetelene tourch and gently heated the mating surfaces just over the shaft. I also had a Vice Grip clamped on the shaft, and when I got the manifold nice and red it came loose easily and has been free ever since.

A hand held propane tourch may work, but it may not get it hot enough. If you have access to an oxy-acetelene tourch, give that a try.

Heat where the arrows are pointing

Merle

Merle,

You are correct, a hand held propane torch won't get it hot enough. I tried that before cutting mine out. I don't have an oxy acetelene torch.

[chucky07]

thanks guys..you are surely more experienced than I..as it's my first engine project...Since I don't have a good torch...I guess I'll run it as is...I was just worried it would ruin my new engine.

maybe I can get her fired up this weekend if all goes ok..

[Young Ed]

I would buy the kit and if nothing else have the shop that did your engine machine work install it for you.

[Merle Coggins]

It looks like your's is stuck halfway closed. This may cause a slight exhaust back pressure to the front cylinders, or add additional heat to your carb base. You could fabricate a block off plate to go between the manifolds to block the heat to the carb base, but that may increase the back pressure.

If I were in your shoes, I'd find a local shop that'll use their torch to heat the spots that I pointed out. You'll be surprised how easily it'll free up. Worse case, it'll cost you a bit of labor cost at the shop. Best case, it'll cost you a 12 pack and you'll gain a good contact for future help.

Merle

[MBF]

I removed the one on my '36 Plymouth while I had it apart and put a block off plate in its place. If they stick closed or parially closed you're going to have backpressure problems. Chrysler dealers used to sell some type of penetrant spray that was designed just for heat risers (probably just a high temp penetrant). I don't know if that would help free yours up, but it does help to keep them moving once they're free. I used neverseize on the one on my '52 1 ton while I had it apart and give it a shot of PB blaster every once in a while to keep it movable. Mike

[Fernando Mendes]

Does anybody have more detailed pics about spring,shaft exhaust manifold assembly?

[greg g]

I believe there is a tech article on the home site regarding repair/replacement of the heat riser. Click up in the left hand corner of the banner where it says return to to P15 - D24.com and go to the maint section.

I welded mine in the horizontal position and use a block off plate to seal off the hole. I heve run in 30 degree temps with no ill effects. I have a Fenton dual intake.

[Vazlov1949]

I have had good luck with MAP gas cylinders. Gets almost as hot as acetylene.

[Fernando Mendes]

When the engine is cold,the counterweight lever closes the valve and directs the hot exhaust gases against the intake manifold.As the engine warms up the thermostatic(or bimetal) spring expands and opens the valve directing the exhaust gases into the exhaust pipe.

[greg g]

I guess I should add a note that I keep my car in the garage ad it never gets much below 45 degrees in the garage. If you live where it gets colder and are starting a car that has sat outside in 10 or 20 degree temps. then the heat riser might be more of an issue. Remember in the 70's that most cars hada sheet metal furnace around the exhasut maifold. This fed a thermostatically controlled flap that pulled intake air around the exhaust mainifold till the car warmed up. So instead of warming the manifold, they warmed the intake air. I suppose that zip tying the heater hose to the intake maniflold might warm it up enough assuming that the heater is on.

[Fernando Mendes]

According the D-14966 manual, exhaust manifold WITH heat control valve only for trucks B1-B,B1-C(up to engine nº T142-73728,B1-D(up to engine nº T146-29890).Is it right?

[TylerB46]

When it comes to installing a new kit, do you have to weld the flange on?

[Fernando Mendes]

[P15-D24]

http://p15-d24.com/page/p15d24/tech/heat_riser_adviser.html/

[Don Coatney]

18 minutes ago, P15-D24 said:

http://p15-d24.com/page/p15d24/tech/heat_riser_adviser.html/

Should be mandatory reading for all members.

[d.dunavan]

Replacing the heat riser in my 50 Plymouth, just wondering what size drill bit used. 
 

D.