Help/Problem with fuel delivery adjustment

[houdel]

I decided to to turn up the fuel delivery on my Deuce a tad, without benefit of a boost or EGT gauge. I figured turning it up one flat on the adjusting nut wouldnt get me in too much trouble since 1. My deuce seems a little short on power; 2. I don't get any smoke no matter what I do, and 3. I have a C turbo, which is a little low on boost compared to a D turbo. I carefully read Bjorn's comments in http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=303 and figured it was a low brainer project. I'll wait to get the boost gauge and pyrometer installed before I try to turn the fuel up any further.

That was, untill I got started. First problem, the fuel delivery adjustment was hidden under a cap which was safety wired in place. Wire cutters and a needle nosed plier solved that problem. Next problem, my adjustment device didn't match the photo Bjorn showed in the above link. Instead of a screw with an adjusting nut and lock nut, I had a sort of cap nut covering the adjusting screw and the locking nut behind that (see the attached photo. Sorry that the pic is a little fuzzy, it is a hard location to take a good photo of, and my camera doesn't do marco photos very well).

So far, so good. I loosened the cap nut, marked the top flat on the adjusting nut so I could tell how far I turned it, and proceded to turn the adjusting nut clockwise to turn up the fuel delivery. That is, I TRIED to turn up the adjusting nut, but it was very reluctant to turn in. Backing it off was no problem, but turning it in it past the original setting took a lot more force on the wrench that I thought was right. It did get it turned in close to 1/6 turn, but that was as far as I was willing to go. I've wrenched enough to know when something is wrong, and there was definately something wrong here. That nut did NOT want to go any farther.

So what is wrong here? Is there some sort of secret password I need to know to get this nut to turn? Is my fuel turned up as much as it will go? I had the engine stop cable pulled out to the stop position and the engine was not running. Do I need the stop cable pushed in and the engine running to make this adjustment? It feels as though the delivery adjustment screw was up against a hard stop, but that doesn't seem right. What do I need to do to increase my fuel delivery. Any thoughts and comments will be gratefully appreciated!

 

[jasonjc]

Lee I'm not shure but ifrom your pic but I think you need to go down a little more below that pice of safty wire is a cover with 2 bolts
you can see one to the left of the cap nut. I hope that helped some??

 

[Djfreema]

That nut might be a safety nut that the rod bottoms out into at its premeasured depth to prevent turning up the fuel anymore. I would try taking the safety nut off first the do your adjustment and replace the safety nut with a regular nut. Hopefully that makes sense.

 

[cranetruck]

Lee, you have to look at the base of the FDC, you are messing with the calibration of the FDC itself if you adjust the settings on the top part.
The adjustment screw looks like this (adjustment viewed from the bottom of the removed FDC unit) and it looks like it's still safety wired in the lower part of your picture.

 

[devilman96]

Might have a diffrent style metering rod in it... I have ahd 2 former GIs telling me stories about having to get spare rods and take them to the shop to be turned in order to bump the fuel on the M35 their units use to use... I kept thinking they were just BS'ing to BS but maybe the newer style IP's are diffrent in this matter...

Any takers?

 

[cranetruck]

Here is a better picture.
See the nuts/adjustment at the very base? Losen the outside nut and turn the inner nut, it will move the screw in or out, adjusting the extent of movement of the stop block inside.

 

[ken]

After pulling that cap off, Turn the lock nut counter clockwise to release it. Then take a 3/32 allen wrench and rotate the screw clockwise. Turning the screw is what changes the fuel rate. Not the nut. The nut only holds it in place. Turning the screw into the housing/ clockwise when facing the cab will increase the rate.

 

[cranetruck]

HMMM...you may not all have the allen wrench option, the unit pictured above does not, but turning the inner nut will make the screw move in or out.

 

[ken]

The allen screw is located behind the servo pressure valve acorn nut in the pic.

 

[cranetruck]

Okay, I think I see what you are doing, Ken, according to the manual, the screw hidden by the acorn nut is for calibrating the FDC itself, but it will also adjust the fuel delivery.
It is used to set the movement of the stop block for the different fuels.
However, once the FDC is calibrated, then the overall maximum fuel delivery is set by the screw at the base of the unit. It will not upset the calibration of the FDC.
Personally, I wouldn't mess with the calibration of the FDC, it would have to be recalibrated on a bench set up where the deflection of the stop block could be accurately measured for the different fuels used.

Would you agree with that explanation?

 

[ken]

Yes your right. The main reason for this adjustment is calibration. Lifting this stop block allows more fuel into the chamber. I learned this adjustment from boyce equipment a few years ago. It works pretty well.

 

[houdel]

OK, I get the picture (literally). I was messing with the servo pressure valve, thinking it was the fuel delivery adjustment. Just have to look a little lower on the FDC to find the right part. Let you know how I make out. Thanks all for the help!

 

[houdel]

Yup, I had my sights set too high, literally. The part I was messing with was the servo pressure valve, not the fuel adustment. As mentioned above, I had to cut the safety wire just visible in the bottom of my photo, remove two screws and the triagular plate on the bottom of the FDC, and there was my fuel adjustment screw! I guess the military doesn't want anyone messing with the fuel adjustment, they sure make it hard to get to!

Anyhow, I marked the top flat of the inner nut so I could keep track of how much adjustment I was making. I cranked the nut in one flat (1/6 turn) and took my deuce for a spin. What a difference!

The first thing I noticed was a great improvement in starting. Previously, it took a couple of seconds to get all six cylinders firing. Kind of like the old Pratt-Whitney radial aircraft engines, first one cylinder fires, then a second, then another until all were running. My deuce started in much the same manner - I could almost hear the cylinders starting to fire one at a time, it would take 2-3 seconds for all six to get firing and then rough for 5-10 seconds before it ran smoothly. After cranking up the fuel, the engine started up after 1-2 revolutions and ran smoothly right away!

Got her out on the road and tried a smoke test. Stopped on a straight section of road with no traffic around, put it in reverse and punched the throttle. I was rewarded with a decent puff of black smoke! Not a great cloud of smoke but a good puff. It has never done that before. When I drove it home 230 miles from the DRMO, my wife was following in a chase car and said she never saw any smoke from the exhaust! So far, so good.

During my drive I noticed the Deuce was much more responsive to the throttle. The real acid test was the long uphill climb to my house. After turning off the main road to the road I live on, I have about a 1/4 mile of fairly level road followed by a 1/2 mile steep upgrade. Previously, if I thrashed it through the lower gears on the level road, I'd get to the top of the hill at 1400-1500 rpm in high gear. This time I took it a little easier in the lower gears and topped the hill at 1700-1800 rpm! I am happier in than a pig in poop!

All this with just 1/6 turn on the fuel adjustment nut! Can't wait to see what onother 1/6 turn will do! I WILL wait though until a get a boost gauge and pyrometer in place. Will order those tomorrow. The boost gauge will be a piece of cake, I already have a tapped hole in my intake for the ether start system, a 1/8" tee will give me a port for the boost gauge. Tapping a hole for the pyrometer will take a bit more effort though.

Bjorn, I don't know how you manage to do all the work you do on the FDC and turbo working in such tight quarters. Do you have Dzus fasteners on your fenders, or do you have removable inner fender panels?

Come to think of it, removeable inner fenders might be a good idea. I could sawzall the inner fender panels out, leaving about a 1/2" flange around the outside of the inner fenders where they attach to the fender and body. Pop rivet a flange around the portion of the removed part of the inner fender to mate up with the flange left left in place, and use Dzus fasteners to join the two pieces back together again. Make it a lot easier to service the fuel injection pump and turbo. A couple of Dzus fasteners holding the fender inner to the frame will cut down on the noise fron the inner fender flapping on the frame also. What do you think of that idea?

 

[24-VOLTS]

Lee,

I think the idea of a removeable inner fender pannel would be awsome !!
Maybe something to fab up and sell !!!
I have the heater installed and is a pain in the you know what !!!

And as far as a oil test for your engine oil. Any Caterpillar Deal does that for engines.
It is standard with any oil change on any CAT engine. With that test they can even tell when an engine is going bad.

Phill

 

[OPCOM]

From this, then, to be clear, the stop plate adjusting nut is to be turned counterclockwise to increase fuel flow, and this also moves the delivery adjustment screw in, having the same effect as though the screw had been turned clockwise, yes?

This would at first glance imply reverse threads on the screw according to the text from the manuals and the accompanying images, -- but the directions say "as viewed from the governor end of the pump"! -reversed view than what the first picture shows as we are viewing the assembly sort of from the 'drive' end of the pump. tricky!

Sorry to be so dumb, I just want to understand. At least I can keep my crayons inside the lines!

 

[doghead]

From this, then, to be clear, the stop plate adjusting nut is to be turned counterclockwise to increase fuel flow, and this also moves the delivery adjustment screw in, having the same effect as though the screw had been turned clockwise, yes?

This would at first glance imply reverse threads on the screw according to the text from the manuals and the accompanying images, -- but the directions say "as viewed from the governor end of the pump"! -reversed view than what the first picture shows as we are viewing the assembly sort of from the 'drive' end of the pump. tricky!

Sorry to be so dumb, I just want to understand. At least I can keep my crayons inside the lines!

NEGITIVE, NO, The previous mention of turning the nut counterclockwise was to loosen the jam nut only. To increase the maximum fuel rate you turn the inner nut clockwise ,then reset the jam-nut to hold it all in place. (while you do this you do not let the screw (threaded stop rod) it self turn or damage will occur internally)

 

[OPCOM]

I see, so facing the nuts, turn the jam nut counterclockwise to loosen it, then while making sure the screw does not turn, turn the adjusting nut clockwise. Then re-tighten the jam nut. Ok. Thanks for helping me to understand.

 

[doghead]

I see, so facing the nuts, turn the jam nut counterclockwise to loosen it, then while making sure the screw does not turn, turn the adjusting nut clockwise. Then re-tighten the jam nut. Ok. Thanks for helping me to understand.

Correct!

 

[FormerNewMVGuy]

[
NEGITIVE, NO, The previous mention of turning the nut counterclockwise was to loosen the jam nut only. To increase the maximum fuel rate you turn the inner nut clockwise ,then reset the jam-nut to hold it all in place. (while you do this you do not let the screw (threaded stop rod) it self turn or damage will occur internally)

If the stop rod turns, what kind of internal damage will occur?

 

[doghead]

Bad internal damage. Why do you ask? I'm really not sure what would be damaged. Above, is a picture posted by Bjorn, when he added a rheostat to his FDC. Maybe he has a better answer.