manifold heat control valve

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dartpower

dartpower
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anyone with a slant six 225 answer my question do you need to have a heat riser working .i seem to be losing heat out of the shaft going back against my fire wall .can i weld a steal o-ring in that shaft area to stop the air leaking and is this okay to do.i've been told that you dont need the heat riser working some guys blank it off is this a good thing or will it cause problems.the other trouble i have is that if i drive say for a hour and shoot off the engine say for at least half a hour she is hard to start what is causing this to happen.i;ve just changed my 225 to the( super six slant 6 225).shes a 67 dart.
thanks
chris in canada...
 
Cold weather driveability is the issue if it's not working. There are NOS and aftermarket manifolds available.
I have a truck manifold that didn't come with the heat valve. I ran that in the door car until changing out to alternative manifolds that offer no carb heat at all. I don't drive the car much in cold weather. So far it hasn't been an issue, but it doesn't get very cold here, and I don't drive it when the temperature is down.

It's not that it will run poorly once the engine is warmed up. The intake manifold will eventually warm up, but until that time fuel will drop out causing mixture problems.

You should be able to sleeve the bore for the shaft. Once iron has been welded, it can develop cracks. I'd avoid welding if possible. Some folks have had good results doing it, though I'm not one of those people.

CJ
 
Mine is also not working right, and no one (the Dodge dealer, Napa auto parts, etc.) can seem to locate a rebuild kit, and all the slant sixes are gone from the pick your parts around me. I have a 67 with the square weight (as opposed to the later years ound weight). If I am standing at the bumper in front of the car and looking toward the windshield and at the engine, it will be in what position if i turn it clockwise? so the top of the square moves toward the driver side? I know it only turns about 1/4th of a circle, but I want to make sure that in my situation in southern california, it is not sending hot exhaust to the intake.
Thanks!
 
I would get it working if possible just to have better warm-up performance if nothing else. If not, turn the shaft counterclockwise (standing in front of the car looking toward the rear) to open it up. Make sure the shaft is turning and not just the weight. If it's frozen, use some WD-40 and a small hammer to tap the shaft back and forth in the bushings to free it up. I wouldn't weld on the manifold. Those things are crack prone to start with. If you really have to remove the whole heat riser, I'd remove the manifold from the engine and grind the welds on the flap, drive out the shaft, and tap the bushing for a plug or remove the bushing and install a steel freeze plug.
 
I attached two photos - hope it works!
 

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Can someone confirm I have the correct directions on this. I am standing at the front bumper facing the engine and the windshield. Thanks!
 
Yes, just like a faucet.......right=closed, left-open. Either way the intake is heated by the exhaust but when it's open the heat is directed out to the pipe and not up and around the flap where it blasts the intake and resticts flow.
 
Help! In trying to free up my heat riser, on my '69, the counterbalance came off the shaft. Is there any special way to put it back? Assuming I am able to free up the shaft using WD 40 and visegrips?
 
Assuming you have all the pieces, and they're not broken, it should only go on one way. One of the pieces fits in the shaft slot and also in the weight slot (check the photos above) If you try to put it 180 out, the weight will hit the stop pin.
 
Even if the shaft turns, the internal plate could be corroded away so it doesn't function. The one on my 69 Slant Six was frozen stuck, so when I had the manifold off (for other things), I removed the heat riser. I wanted the option of installing one someday (if new parts ever appeared), so I used a bolt and nut to seal each hole. I used the the type nut with a round washer head and grooves under the washer, with the nuts inside. They never came loose in 10 years of driving. You might use stainless steel, but a little corrosion might be good to keep it from unloosening. You could use a single bolt thru both holes (my initial solution), but don't overtighten or you might crack the manifold. That is one way to do it with the manifold on the car.

I drove that 69 Dart for 2 winters in South Bend, IN and I don't recall unusual problems with it heating up, even on -10 F mornings. If you someday switch from a carb to TBI, I don't think those need a heat crossover. For sure MPI doesn't. I understand the main reason for the heat cross-over is to prevent ice buildup under the carb, meaning steady-state driving in cold and damp climates. The "heat riser" valve aids in the secondary benefit of a faster warmup, but isn't essential. What affects things more is if you block off the cross-over, which many do in V-8 engines for racing, or which slant-sixers do by installing headers.
 
Can you A) easily change from one style to another? From the older square weight to the newer round weight, for example? Is it as easy as taking off one and installing another? Or do you have to drill/weld something?
And can you B) lock it into position where you never heat the intake, if you live in Southern California or Florida, for example, and it never gets snow? That would be the opposite of the post/stop, right? I know you can wire it to the stop so that it cant move, but how do you wire it away from the stop? Just take off the spring and hope it doesnt move while driving?
 
Can you A) easily change from one style to another? From the older square weight to the newer round weight, for example? Is it as easy as taking off one and installing another? Or do you have to drill/weld something?
And can you B) lock it into position where you never heat the intake, if you live in Southern California or Florida, for example, and it never gets snow? That would be the opposite of the post/stop, right? I know you can wire it to the stop so that it cant move, but how do you wire it away from the stop? Just take off the spring and hope it doesnt move while driving?
No, the early stamped steel weight is a clamp-on type.....the round cast weight is a press-on and can break if you're not carefull. Yes, you can "wire" it open if you think you need to. Unless you make a solid gasket plate dividing the exhaust from the intake manifold, it will still heat the intake. When the heat riser is in the cold position, it just heats it more.
 
Cold weather driveability is the issue if it's not working. There are NOS and aftermarket manifolds available.
I have a truck manifold that didn't come with the heat valve. I ran that in the door car until changing out to alternative manifolds that offer no carb heat at all. I don't drive the car much in cold weather. So far it hasn't been an issue, but it doesn't get very cold here, and I don't drive it when the temperature is down.

It's not that it will run poorly once the engine is warmed up. The intake manifold will eventually warm up, but until that time fuel will drop out causing mixture problems.

You should be able to sleeve the bore for the shaft. Once iron has been welded, it can develop cracks. I'd avoid welding if possible. Some folks have had good results doing it, though I'm not one of those people.

CJ

thanks for your input ,what i did was to make a sleeve turn down on the lathe and has a set screw with a collar type like a flange style, on the sleeve slid the sleeve on the shaft .but i till have some air escaping out ,but not as much .also put a alum. plate under the carb extanding out past the carb bowl .but i still have this re-start troubles after driving for awhile??? why can anyone add to this problem ..the only thing solved is not alot of hot very hot air back against my fire wall and harding up the wiring runing along the fire wall.
thanks all
dartpower ....
 
A few more scraps of info. My 65 Dart 273 has a round weight on the heat riser and the shaft moves freely. I don't know if original for V-8's. Will check the manuals. My 69 Dart 225 had the stamped steel weight. I recall there was a flat on the shaft that oriented it. Anyway, the weight fell off on the road. The round weight appears a better design.

The factory manual says to periodically spray the shaft with a special solvent (from dealer) to keep it moving freely. Has anyone tried getting it at a dealer today? WD40 or such is probably similar.

dartpower has the opposite problem of exhaust gas leaking past the shaft. I recall that when I did the "bolts in holes" fix, I coated the bolts with "muffler bandage cement", which I had lying around. It comes in the muffler repair kits in auto parts. You could probably also use "furnace cement" (Ace Hardware) or some of the copper anti-seize products. Maybe even high-temp RTV, but you pushing its limits. The shaft collar will probably seal after a while as carbon from the exhaust clogs the small passages.

The "heat on firewall" problem is probably due to an exhaust manifold leak. Start the engine cold and place your hands around it before it gets too hot. You should feel a puffing, and even hear it. If you catch it soon, you can often fix by just tightening the manifold nuts. Also check the intake-exhaust joint and the exhaust pipe flange. There are products to keep the manifold nuts from loosening, but are usually bolts so you must remove your studs first, which runs a risk of snapping a stud off, so wait until the heads are off someday. Your exhaust manifold may also have a crack. That is a problem with all 6-cylinder exhausts and even the heads. Mercedes six cyl diesels are notorious for cracked heads (5 cyls almost never crack), which is why people try to unload their over-heating station wagons on newbies, saying "maybe just a heater hose".
 
A few more scraps of info. My 65 Dart 273 has a round weight on the heat riser and the shaft moves freely. I don't know if original for V-8's. Will check the manuals. My 69 Dart 225 had the stamped steel weight. I recall there was a flat on the shaft that oriented it. Anyway, the weight fell off on the road. The round weight appears a better design.

The factory manual says to periodically spray the shaft with a special solvent (from dealer) to keep it moving freely. Has anyone tried getting it at a dealer today? WD40 or such is probably similar.

dartpower has the opposite problem of exhaust gas leaking past the shaft. I recall that when I did the "bolts in holes" fix, I coated the bolts with "muffler bandage cement", which I had lying around. It comes in the muffler repair kits in auto parts. You could probably also use "furnace cement" (Ace Hardware) or some of the copper anti-seize products. Maybe even high-temp RTV, but you pushing its limits. The shaft collar will probably seal after a while as carbon from the exhaust clogs the small passages.

The "heat on firewall" problem is probably due to an exhaust manifold leak. Start the engine cold and place your hands around it before it gets too hot. You should feel a puffing, and even hear it. If you catch it soon, you can often fix by just tightening the manifold nuts. Also check the intake-exhaust joint and the exhaust pipe flange. There are products to keep the manifold nuts from loosening, but are usually bolts so you must remove your studs first, which runs a risk of snapping a stud off, so wait until the heads are off someday. Your exhaust manifold may also have a crack. That is a problem with all 6-cylinder exhausts and even the heads. Mercedes six cyl diesels are notorious for cracked heads (5 cyls almost never crack), which is why people try to unload their over-heating station wagons on newbies, saying "maybe just a heater hose".

thanks for the up-date info.anyway i do know i don't have a leak in the manifold or crack .the hot air is definely coming out from the heat riser shaft tat i had made a sleeve to side or and tighten it onto the shaft with a set screw to keep in place .thinking maybe take the info that was talked about and turn the shaft couner clock wise and make another sleeve just a slight smaller and see if any air is escaping after wards .or set back up the heat riser valve by buying new .but been told by alot slant customers don't really need it .i think i do living in cold wether nova scotia ,canada .i use my dart as a daily driver.still a great car show car ,and well taken care of.
thanks all for great advise and info.
dartpower!!!!!!!!!!
 
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