So who has bumped the power on a 6CTA cummins

CARMAN

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[h=1]Thread: So who has bumped the power on a 6CTA cummins[/h]
Tonight is the night! Started last night but on my fuel adjustment cover one side was slotted and the other an allen head. But of course I did not have metric with me and none of the standard fit. I could have cut a groove in it and made it a flat head but they are tight and seemed a little soft. Don't want to break it off.
IMG_2093.jpg
 

CARMAN

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Ok. So metric do not work so I made my own. But that did not work as it just wobels out the hole. So I took the other advice on here to notch the head grabbed it with vice grips but she still won’t move. Slot just keeps getting bigger. (Keep it clean boys). Should I just pop the head off and hope I can get the threads out? Just can’t get any purchase on it. ?? Feel free to call as I’m standing in the truck
703-963-1411
 

aziator

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For some reason I thought I remembered guys saying they had to drill that out. I am looking through past threads now.


OK, thread that I saved a while ago says if you have an anti-tamper bolt to cut an notch into it then use a chisel to loosen, or vice grips, basically whatever you can use to get it off.
 
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CARMAN

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Ok. Got it off. Had to take off the throdle cable mount. However. Looking in the hole. My 10mm nut is out all thday way. Wtf. Only like 1/8” thread showing
 

nevrenufhp

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I have found the quickest way to get that screw out is to drill off just the head with a 1/4 drill bit. Then there should be enuf threads to grab with pliers or vise grips to take out. It's a coarse thread 4mm bolt, but cant remember the length(around 20mm long).
There are quite a few with that slotted setup. Needle nose pliers fit in there pretty easily. Back off that nut til at least those threads disappear. It will likely be fine with the stud flush with the slotted part of the nut.
 

CARMAN

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Will have to look at it another day. Put it all back together since I assumed there was little to no adjustment available.
 

74M35A2

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nevrenufhp has been a great resource here for the Bosch MW injection pump tickling. We're lucky to have him.

For anybody jumping into the middle or end of this, the screw on the top portion of the pump under a cap is for pre-boost fueling. This is said to make a large difference in stop light take off type situations, as the 8.3L is anemic in this area. The adjustment nut at the rear of the pump, as show in the pic just above, is the fuel rack travel limiter, which affects the full throttle fuel delivery rate. This one is said to make it feel like you swapped out the engine with something more.
 

CARMAN

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The other issue I had was that when I slid the deep well socket to check size on the larger nut I could not get it on. Almost as if the right size socket was too thick of a side wall to go over nut even though it fit in the hole.? But if I back out the slotted "round" nut maybe I can back out the larger one with a screw drover and then re install the slotted nut.
 

Patriot6X6

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Hello everyone. I am new to this forum and new to owning a military truck (87 Harsco M923A2). I have recently read over this entire thread multiple times and was curious if anyone who has done all 4 mods to the injector pump (fuel screw, star wheel on aneroid valve, idler springs, and full fuel screw on the rear) have issues with EGT’s? I see so many people have put EGT gauges but no one has ever posted them getting too hot. I was wonder because I would like to make some adjustments just to get my truck moving a little better than I does. Thanks for your input.
 

74M35A2

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It depends on how much load you put on the engine. For example, towing or up freeway hills. Once you increase the fuel rate, you will then be able to melt pistons if you are not careful. This means driving by the EGT gauge. If going uphill, you’ll have to watch the EGT and either downshift or let up on the pedal some. With stock pump settings, you can just floor it everywhere without fear of a melt.
 

panzerwillie

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The pump on the M900 series 8.3 is similar but not the same as the smaller brother 5.9l, with that in mine, does mods will wake is it enuff for a great running truck as far of the EGT's the exhaust housing is good diameter so you should be good, probably would not be a problem unless you pulling heavy loads on mountains, unless you change injectors or delivery valves i would not loose any sleep over it, i did both of mine over 5 years ago and still running good.
 

Patriot6X6

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I never pull anything with my truck but the main reason I want to adjust it is because of the hills in northeast Pennsylvania. It practically gives up before it even starts to climb.
 

74M35A2

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Shouldn’t. Make sure you have a good state of tune before you begin. Clean fuel and air filters, dip tubes and soft fuel lines not sucking air, brakes fully releasing, proper tire pressure, etc....
 

Patriot6X6

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Yeah. I went through all of that. I am a truck driver so I am no stranger to air brakes. As for the air filter and fuel system it has all been replaced. When I replaced all the fuel lines, up tube and filters I did see a difference in normal driving but it is still very sluggish on the uphills.
 

WillWagner

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The pump on a B series....on road anywho, is a P series, 7100 with RQVK governor. The on road pumps for the C were MW, which is what the 900 series trucks have, with rqv governor and, later in life, 1994 and above, P with RQVK. B series never had MW pump. They are a PITA to work with.

@74M35A2, how's your transplant coming?

Been a bit since I messed with you!
 

Jeepsinker

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Jeepsinker what is an overflow valve and where is it located?
Basically it's the whole banjo bolt that connects the fuel return line to the injection pump. It has a small wire spring in it and a ball bearing and seat that act as a pressure relief valve. They're very susceptible to corrosion and wear. This bleeds off internal fuel feed pressure in the pump which causes power loss, and in extreme cases even causes hard starting.

It's the banjo bolt in the line coming off the side of the pump at the front end. Don't buy a factory replacement. They're junk. Google " Torktec OFV-20" and buy that. They have stainless internals, stainless spring, and a hardened seat. They're also adjustable so you can raise your fuel pressure, but they come preset at factory spec.

Higher feed pressure will provide more power all by itself.
 
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