Stupid Roosa Master Injection Pumps!

ok guys, today i wanted to give my 1971 4320 john deere some more fuel. i own a 1985 GMC 6.2L diesel and ive tweaked the fuel delivery on it multiple times. its real simple. and you can do it through the top cover. anyways, on the 4320 it has a similar injection pump, and i figured this will be the same sort of operation to do, just in a smaller area. well i took the top off and the guts out(super simple) and opened the timing cover on the pump to drain the fuel out of it to make seeing the screw easier. then i took the timing cover off the clutch housing to turn the engine over to line up the screw and the access hole. well i spent 2 hours turning the engine and finally got it lined up. then i went to put the allen wrench down in there to give it 1/8th of a turn and the damn wrench wouldnt fit. the throttle shaft was in the road. so how do you tractor pulling guys do this? or do i have to completly rip the pump off the tractor, remove the throttle shaft to do this simple operation, that only takes me half an hour to do on my 6.2L diesel truck?

I'm no diesel expert but a JD 4320 compared to a GM 6.2L? Seems like they'd be at complete opposite ends of the spectrum. I think you're asking for trouble just randomly turning a screw without the aid of a dyno and other test equipment. Dave

i know theyre completly different. but the pumps are very very similar. theyre both made by stanadyne and theyre both DB2 models. anyways, ive done this on the 6.2 and it worked awsome. i was only going 1/8th turn on the 4320 just to get the boost up to 20 psi like its supposed to be. right now it only goes to 10 psi.

I second what 135 Fan said, would not recommend such a shade-tree operation without specialized knowledge and instruments. Tom

i know guys, thats why im only going 1/8th turn. ive talked to 3 older diesel mechanics before i started tearing into it. they said go for it. it wont hurt it as long as you dont go past 1/8th turn. but i never asked them how to get to the darn screw! i figured it was the same as my 6.2's pump, and easy to get to.

I don't see anything about reading temps on an exhasut pyrometer.
Install one of those first before tinkering with the pump.

yea that run across my mind. anyways, guys please stop beating around the bush on why not to do it. i just want a little more jam to pull my cultivator. ill be backing it off once i get new injectors for it since this idea is only going to mask the worn injectors i have.

You might want to check the timing advance,
if the barrel where the advance plunger works
is slightly worn ,you may not be getting the
full advance. That will make some black smoke
if it not real bad , if real bad will make the
stack glow dull red in low light when real bad
will also cause rough running above 3/4 throttle.
The soot created will stick in the ex manifold
and restrict the flow keeping the turbo from
running up to speed causing low boost.

george

it doesnt smoke that much at all. the pump had a new flex ring put in it about 1000 hours ago so im guessing it was rebuilt then too. the injectors have 9600 hours on them though. it smokes blue at hot idle all the time. burns no oil, so thats a classic bad injectors sign. plus it wont start unless its almost 80*F outside unless you give it a "sniff" of ether.

I don't understand your problem, if you have the guts out like you said, then you have the throttle shaft out at you need to get it and the govenor guide screw and spring out of the way.

i had everything except the throttle shaft out. i cant take the throttle shaft out for 2 reasons, 1 i dont know how, and 2 i would have to remove the pump from the engine since its so close to the block the shaft wouldnt come out far enough to clear the power screw access hole.

Your classic sign ,blue smoke at hot idle and
the fact it won't start on a cool day says you
may need injectors , but it says you need a set
of cyl kits and set the valve recession to the
proper value.Deere is quite finiky about valve
recession, about one valve grind and you need
a set of seats to get the valve up out of the
head and get you compression back to cure the
starting problem.

george

so it sounds to me like i need a rebuild. so rings, liners, bearings, get the head completly redone, redo the injectors and ip. then call it good?

Pump may not be bad now that you tell us more
of the symptoms . Put the injectors in or at
least pop test them and adjust the opening
pressure to spec, that the low budget thing to
do first, if that doesn't help , save your
pennies cause it takes a pile. I have a repair
and machine shop , been doing truck and tractor
overhauls for at least 35 years as well as the
roosa master pumps.

You MIGHT be able to get an 1/8 of a turn on the screw BUT if the pump re-builder put it back to factory then he would have put the shims back under the retaining clamp. If he did this, like John Deere's have from the factory, you can't get the screw to tighten on the clamp any more. I have had to fix several pumps where the owners "tried" to set the fuel up and twisted the screw off. If this happens about half of the time you just scraped the rotor. The last new one I put in was about six hundred bucks.
So you can take the same money and replace the injectors or gamble on a pump repair.
I am not a fan of turning up injection pumps. The rest of the tractor is made for so many horsepower. When you create more at the engine then you may make other things fail.

well that just riles me right up! oh well, thanks for telling me that before i twist the screw off! how hard would it be to take the rotor out and remove them shims?

If you don't know how to remove the throttle
shaft , you have no business deeper in the pump.
If you are going to play with fuel settings,
you need the tools, the specs,and the test
stand.Also some experience would be helpful.

george

Bad injectors will ruin an engine about as quick as anything - except ether !

If you know you have bad ones get them fixed or replaced before you burn a hole in a piston. Sounds like it's too late though ? That ether may of broke the top rings thus no good compression to start.

I'm wondering why you're calling the Roosamaster pump stupid? I think Vernon Roosa was a pretty smart guy. His pump set the stage for many tractor companies to change over to diesel. And, companies like CAV, Lucas, Rotodiesel, and Bosch paid for permission to copy it and use in Europe.

I can turn the pump up in your 4320 in 10 minutes. Just pull the long anchor stud out (takes a 7/16" wrench), and take out a lock-clip, slide the yoke over, and you THEN reach in with the Allen wrench.

As far as your 6.2 goes, if you already have a J-code engine, turning up the fuel accomplishes nothing. If it's a C-code, it buys you a little power. But, the J-code pump has a larger delivery valve then the C-code pump and turning up the C-code pump does not work as well.

Here's all the pumps used on 1988 6.2s. LD pumps have the small delivery valve and HD pumps have the big one.

DB2829-4524 23500416 1986-89 HMMWV (Military) C/K — —
DB2829-4544 23500346 1986-88 HD C/K & P Truck C/K — —
DB2829-4548 23500587 1986-88 Industrial - 12V (Clark) C/K — —
DB2829-4554 23500931 1988-89 LD C/K Truck (Auto. Trans.) C/K — —
DB2829-4555 23500933 1988-89 LD C/K, R/V Truck - ALT. (Auto. Trans.) C/K — —
DB2829-4574 23501280 1987-88 Generator - 24V (Clark), 1800 RPM C/K Made from
DB2829-4548
—
DB2829-4581 23500932 1988-89 LD C/K Truck (Man. Trans.) C/K — —
DB2829-4582 23500934 1988-89 LD C/K Truck - ALT. (Man. Trans.) C/K — —
DB2829-4612 23501993 1987-88 Industrial - 24V (Clark), 3600 RPM C/K Made from
DB2829-4548
—
DB2829-4636 23500941 1988-89 LD G Van (Auto. Trans.) G — —
DB2829-4637 23500942 1988-89 LD G Van (Man. Trans.) G — —
DB2829-4638 23500943 1988-89 LD G Van - ALT. (Auto. Trans.) G — —
DB2829-4639 23500944 1988-89 LD G Van - ALT. (Man. Trans.) G — —
DB2829-4646 23502177 1988 HD C/K, R/V, P Truck & G Van G DB2829-4723 Note 7
DB2829-4647 23502178 1988 HD C/K, R/V, P Truck & G Van - 1.2 cSt G
DB2829-4724 Note 7
DB2829-4648 23502179 1988 HD C/K, R/V, P Truck & G Van - ALT. G DB2829-4725
Note 7
DB2829-4655 23502229 1988-89 Industrial - 12V (Clark), 3600 RPM, 1.2 cSt C/K Made
from
DB2829-4548
—
DB2829-4701 23503123 1988-89 LD R/V (Auto. Trans.) C/K — —

i figured out how to remove it now. its so simple how these pumps are. thanks for your help. i guess since theres shims under the power screw ill leave it alone.

i meant this darn pump. but it seems john deere put a damn shim underneath that screw so that you cant turn it down any further past stock spec. so i guess, ill leave it alone unless i buy a book and feel ambitious enough to pull the pump apart to remove the shim.

That shim-pack was a Stanadyne thing; I don't believe Deere had anything to do with it.

Most new DB and JDB pumps from Stanadyne came with limit-shims. And many if not most pump shops throw those shims out during the first pump repair. So now, it's kind of rare to find a 20-50 year old pump that still has those shims in it.

oh ok. im guessing theres still a shim in it since i got the allen wrench in the screw a few times and i couldnt turn it. so i gave up. usually the screw turns with less force.

It may already be turned as far as it can go.

I don't want to get you you in trouble but, sometimes those screws turn real hard. It's difficult to tell if that spring is bottomed out or it's just that screw turning hard. Only way to know is try turning the other way (counter-clockwise) and see if it moves. If just as hard, then you know it's just the screw.

I'm also wondering if maybe your pump has no shims but is turned all the way?

If you have the JDB633-JD24000 pump, it's already set at near as far as it can go. It's only a pump with two .33" diameter pump plungers and I think it's already set the highest of all the 633 pumps that Deere ever used. Anything more, they jump to a 635 or 637 pump - with .35" or .37" plungers.
The "633" on the tag stands for six cylinder and .33" inch plungers.