While we're discussing distillate

What does the heat control on a distillate manifold actually do? I understand that its purpose is to warm the intake side of the manifold with heat from the exhaust, but is that happening internally or externally?

External, I can envision a plate that restricts the upward convection of the heat from the exhaust side with a flapper and a shroud. Internal, I would envision something like a manual version of the choke/throttle plate in the exhaust, similar to the exhaust brake on diesel pickups.

Is it like one of those, or something else or in between?

The flapper is inside, just like manifold heat control used on cars and trucks until pollution controls became common. The 460/560 and others with the 6 cylinder C221-up gasoline engine have manifold heat controls to make them run better when cold. They were originally truck engines.

Okay, that makes sense. Thanks!

Next questions . . .

It's the same concept as the exhaust brake on a diesel. It's great for warming up my Cummins (EGTs of 400+* when choked off at idle vs 275* when open), but it's primary purpose is to make backpressure to slow the engine. Would IH's engineering have used it for warming the intake and the fuel/air flowing through it AND for the back pressure to have higher compression when the exhaust valve closed that would raise the pressure in the cylinder for the next combustion stroke to aid in burning the distillate? I know it wouldn't be much volume for a higher pressure (only that between the piston and the cavity of the head), but it's some.

And (I hope I'm not whipping this to death) . . . A diesel will gobble all the air it can get, so an exhaust brake would be the only throttle in the system. It can't block the exhaust completely, obviously (like a potoato in the pipe!) but it closes off a large part of teh diameter of teh exhaust. And it's a lot more effective as a brake at higher RPMs. With the heat selector on the tractor motor set for operation in the cold (as closed as it will get) and the motor at working speed (throttle plate wide open) I can see it working fine. But as the throttle plate closes down to idle, I see a no-man's land developing between the throttle and the heat-control flapper. Am I correct that that is part of the reason for the difference between a gas (idle mixture and speed adjustments only) and a distillate (with the additional adjustment for the load mixture) carb? Ported differently as well? I would also think that the heat-control flapper would be much less restrictive, relatively smaller than an exhaust brake plate?

Scotty - A distillate manifold heat control valve operates totally different from a diesel exhaust brake butterfly.

Internally the manifold heat control is a diverter valve. In the "hot" position it routes exhaust through a passage that surrounds the center section of the intake manifold before sending it up the stack. In the "cold" position exhaust is sent directly up the stack, bypassing the internal manifold passage.

Unlike a diesel brake, the heat control provides no appreciable additional exhaust restriction (back pressure) when set to the "hot" position.

I know nothing about diesels, except that I hate the sound of a "Jake brake" if I'm anywhere near it. Some semi drivers think they are cool, because where I live is flat, and they still use them to slow down. I really had not thought of the reason IH put mixture controls only on the carbs of the distillate/kerosene C113. But, I imagine it was because kerosene or distillate does not burn as well as gas, and it required a leaner mixture to reduce contamination of the oil. That carb tends to run rich anyway, even on gas. Manifold heat control valves should be kept in working order on tractors and cars with gasoline engines because other than kero/distillate, the engines work better with a cold mixture. Perhaps I should say with cold air.

Aha! That killed both questions with one stone. I'll look at Mike's pictures of his again and maybe one day actually get my hands on one, but I can picture it better now.

Thanks, Bob!

Yep, cool air is denser, meaning there's more of it to help with the burn. On turbo diesels, they use an intercooler between the turbo (where it's pressurized and therefore heated up) and the intake to cool it but maintain the pressure (for volume) and regain the density. Boyle's law at work.

The exhaust brake (mine's a Jake but other companies make them, too) is a whole different beast from the ones on the big trucks. Just a butterfly (Thanks, again Jim! I couldn't come up with the word earlier.) that acts like a throttle plate between the turbo and the exhaust piping. When engaged, the exhaust tone switches from rumble/rattle to a hollow metallic whooshing sound, different but maybe even quieter than the regular exhaust.

I use it all the time on the pickup, even running around bareback. Except for emergencies, I downshift against the exhaust brake to slow down or stop and rarely touch the brake pedal, except to finish rolling at a signal or sign. Driving like that, I got almost to 140k miles on an 8000# truck, probably 40k of that towing up to another 12k behind, before it was time for brakes. So I can understand why the truckers you refer to use their Jake even on flat ground.

That said, I hear ya on the Jakes on a big truck with straight pipes. It's a different setup on them than the exhaust brakes on the pickups. On the big trucks, it acts on the exhaust valves but, in fact, on a truck with a legal exhaust, it isn't any noisier -- like the exhaust brake, the tone changes, but not the noise level. Unmuffled, they'll lift you right out of the seat if they're near you when they bump it. School buses and OTR buses (Greyhound, Trailways) all have them and aren't the least offensive. I've ridden with my neighbor with a KW and a big Cat with enough lumber on to make 90,000#+ and even with the Jake turned up high, it's not noisy at all. It's the guys with the straight pipes that are the nuisance. With good mufflers, most folks wouldn't know Jakes even exist.

I'll look at Mike's pictures of his again...

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Scott, when I get my manifold out of the tank, and get the valve free, I'll take some pictures of the inside in both positions.

Bob M is correct, the hot position diverts the exhaust gasses around the inlet manifold to keep it hot, stopping the distillate/kerosene from condensing in the manifold. In the cold position the exhaust gasses go straight up the exhaust pipe. Both my Super A and W-4 manifolds need to have the valve freed up but other than that, both are in very good condition. The one on the O-12, (gasoline, but 60 octane in the 1930s) was new 10 years ago, works very well but running cold all the time on 95 octane, the lowest octane available now. I would like to find the chimney casting that connects the manifold to the muffler for the Super A. Some years ago OEM had them in their catalogue but not any more.

I understand your feelings about jakes, but using them on the flat makes as much sense as anywhere else. The whole point is to reduce wear on the wheel brakes, and it's just as effective on level ground as going down hill.

My REAL complaint is [u:654c4848f0]unmuffled[/u:654c4848f0] jakes. There's no reason on the planet NOT to run the jake through a muffler. I regularly get blown right out of bed by the trucks coming down the long shallow hill North of my house, dragging the jake all the way, delivering fish to the cannery at 3:30AM.

Here's a look from the top of my SH manifold with the valve close to the middle position. In this position most of the gases will go straight up and out but some will pass beneath the valve and through the hot box before exiting. It is easy to see what route would be blocked if the lever is moved up (hot) or down (cold). I was lucky to find a NOS valve for mine.
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Scotty - Punch below! You'll get flow diagrams and photos of a manifold heat heat control valve both open and closed.

This one happens to be for a Jeep and is automatic - ie. it's thermostatically controlled. However the internal workings of an IHC distillate manifold heat control is the same.
heat riser

Again, many thanks!

Thank you, yer honner.

Ah, it's just a nickname a coworker gave me cuz I have an interest in politics

Interesting question and answers everyone. So counterweight down for cold starts and the weight up to close the flapper when warm. After I unstuck it on my 2606 I don't think the spring ever moves it. I'll check the next time. Would the operation of that valve have any affect on mine where I have to have it on full choke until complete warmup to keep it from stalling out in anything but low gear? (I've already been through the carb, carb adjustments, coil, wires, fuel flow to the carb, etc)

Around here they usually use them as soon as they see the "No Jake Brake" sign. I'm a couple miles away from a major highway, so they don't bother me where I live. I heard them all the time at my previous house.

If the flapper is stuck in the "cold" position the engine will generally require more and longer partial choke until the motor fully warms.

Conversely if it's stuck in "hot" you lose a little power under heavy load. It may also have an increased tendency to knock under heavy load.

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Your situation sounds like the carb is set a bit too lean...

Thanks Bob, Guess I still had it wrong though till I read your other posts.

I guess I was thinking bassackwards on the nomenclature here.

Recap for us dummies:

For a cold start on a cold day, I want the flapper in the "hot" position with the counterweight up which then allows exhaust air to flow around the intake air in the intake manifold before going out the exhaust stack. After it warms up or on a hot day, the flapper would be in the "cold" position with the counterweight down which allows the exhaust air to go straight up the exhaust stack bypassing the intake manifold. Is this recap correct?

Your recap is right on!

(quoted from post at 22:23:19 12/04/09) Your recap is right on!

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Thanks Bob. I just looked at it a little bit ago and realized it doesn't have a counter weight on it. Just a round quarter inch shaft sticking out with a slot in it and the spring wrapped around it. The end of the spring hooked over a small post sticking out a little below the shaft. The slot in the shaft was almost perpendicular with the ground but at about 9:30 & 3:30 orientation.

Gotta move some hay tomorrow, I'll try a screw driver in the slot to see if it moves and what it does after warmup.

Will the lack of a counterweight affect it? Thanks.

(quoted from post at 00:56:25 12/05/09)

(quoted from post at 22:23:19 12/04/09) Your recap is right on!

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Thanks Bob. I just looked at it a little bit ago and realized it doesn't have a counter weight on it. Just a round quarter inch shaft sticking out with a slot in it and the spring wrapped around it. The end of the spring hooked over a small post sticking out a little below the shaft. The slot in the shaft was almost perpendicular with the ground but at about 9:30 & 3:30 orientation.

Gotta move some hay tomorrow, I'll try a screw driver in the slot to see if it moves and what it does after warmup.

Will the lack of a counterweight affect it? Thanks.

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Without the weight the heat control valve will not open properly when warmed up. The spring is of bi-metal construction so that as it gets hot it uncoils. The weight is there to ensure that the valve opens completely.

Thanks Owen. Maybe that explains some of my problems having to leave the choke on for so long.

I'll try a screwdriver tomorrow. Turn it counterclockwise to start it and then turn it clockwise after it has run a little while. For all I know, it might be stuck and rusted too. It probably does get plenty of rain down the exhaust.

Well I went out today and moved hay. The 2606 does have a counterweight on it hidden in back of the manifold.

However, it was freezing cold this morning and the counterweight was in the down position. I wonder if the spring is bad? I would think in the cold weather, the spring would tighten up and turn the flapper so it heats the manifold with the counterweight in the up position. With it below freezing, the spring just touches the stop maybe a 1/16" of an inch before the counterweight is all the way down. I would assume the spring just slides out the slot on the shaft sticking out. Thanks.