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The line going from your anaroy valve from your brake valve on dash install a air toggle switch so if you get pulled over you could flip it quick mount it in the ash tray..They are getting a little smarter

Ed

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So what makes these aneroid valves work? I would guess that the manifold pressure has to meet "x" psi before the rack on the pump would have full travel. I also guess that it gets it's air supply from the parking brake so it will have full rack travel while parked. I don't know why that would be a good thing but I need schooled about this. I want to keep the aneroid on my b model because I would like for it to not smoke like crazy but having a valve for those moments when you want more power would be neat.

15 gears...no waiting!
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The mechanic where I used to work mounted an additional air brake knob assembly on the far right panel of the dashboard and covered the words "Parking Brake" with a piece of paper that said "Puff Limiter, in-on out-off". It was after I stopped driving that truck that I realized that was a bad idea and at least he should've known better.

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Jim

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with regard to the e7, someone here might clarify but I am under the assumption they have a different fuel pump and don't have a puff limiter.

My e6 has puff limiter disconnected and is putting fuel in the oil.

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The E7 has a aneroid valve (puff limiter) and if you unhook it it will run worse!!! My E6 had the same setup on it. The valve that the line from the intake goes to is obviously the aneroid valve. Its on the governor. There is a plug that takes an allen wrench to take it out. Get in there with a flat tip screw driver, and turn it so it goes away from the radiator. (If I remember right) The goal is to have less spring tension on it. Its pretty obvious, nothing to screw up. Take it for a little spin. If you went the wrong way It'll be a turd...Just turn it back the other way.

This setup is different than the earlier pumps. You could simply unhook them, or put a valve in the line...

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I have mine on a air switch in the dash.

It does not give more overall power but it does help keep the boost up between shifts as it dumps full fuel sooner. It will smoke more between shifts and can put fuel in the oil.

you should notice the truck is a little faster off the line but thats not because of more overall HP its that the HP comes on quicker at a lower RPM

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So.... After reading the book( Thanks Swishy) I see why it is hooked to the air brake valve. The injection rack requires full fuel to start the engine, after starting, the governor will pull the rack backwards. You would never start the engine without the air brakes set.... Unless you have a B model with a mechanical parking brake. This wouldn't be a problem since my truck looses all it's air pressure when it sits overnight, but going to fix that soon. I will have to run an air valve just so it will start, and a added bonus boost switch.

15 gears...no waiting!
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The E7 has a LDA valve which some call it a aeroid valve.It has to have a line connected to it to the intake manifold to see boost or it will never fuel 100 %.

I never messed with mine on my 96 cl,e-7 but sometimes I wonder if it even works,can't tell any difference as far as smoke coming out of the stack doing a snap test with or without the brake applied,should i see a difference,one think for sure my oil stays clean between changes,there is no soot at all in the engine or the oil,But I have a feeling it should be getting more fuel.

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On the E7 if you mess with the aneroid spring and weaken it , it will make more black smoke and allowing the turbo to spool sooner but only if you don't push the pedal down all the way. Let's say if you never messed with the aneroid and turned the pump up and expected to be quicker off the line. It won't be because they set it up that way to create zero smoke and giving it a delay which is what i feel. Now if you have the spring weakened and floor it, it will just blow black smoke and almost be slower. You need to find the right balance between it all and most of all just control your foot.

I can walk from most macks out there without making any black smoke at all. When you have your puff limiter or aneroid spring messed with, all you have to do is ease into the throttle and then just start to floor it. You can still get plenty of power this way. That is almost the way the truck is setup to begin with, but i feel the aneroid is setup way to stiff from the factory making it very sluggish.

When i first got my e7 i was comparing it to my old e6 300 and it didnt have any torque like my old truck. The e6 with that puff limiter removed gives it instant punch. Thats when i started to mess with things on my e7 and i've been happy.

Slow and Steady Wins the Race!

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  • 5 years later...

If the puff limiter works the way it should. you shouldn't have lots of smoke and it should run as well as the pump is set. 

Releasing the parking brake should send air to the reversing relay in the intake manifold, then from there the air is metered to the puff limiter's 

cylinder on the pump.....which can take a few tries to shim correctly. The reason for working from the parking brake is for full rack travel for cold starts, as an engine requires a rich mixture when it's cold ....so no air to it allows full fuel at cranking when you floor it.   and on that 460, the puff limiter is called an ECM (loL)

Edited by Mark T
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The puff limiter is to limit rack travel to limit smoke. As manifold pressure builds the bimba valve(on inj. pump) allows more rack travel. As long as you have the correct reversing relay and the bimba valve is correctly shimmed, the engine should run just fine. The engine will get full rack travel until the park brake valve is pushed in to aid start-up. On an engine with a LDA, the rack is mechanically restricted until manifold pressure overcomes the LDA allowing full rack travel. 

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