12 Valve Cummins 1991 1/2 questions

[swadees]

Looking to buy a 1-ton flatbed 1991 1/2 4X4 Dodge 12V Cummins from a friend. The engine (intercooled) is stock, 160 hp with 400 ftlb torque. The engine is just getting broken in with only 148K miles on it and runs really good. However the 5 speed transmission seems trashed with lots of sloop in the gear shift, syncros seem worn out. When you pull the selector out of 5th gear into the neutral position, the tranny stays in 5th gear unless you pull the gear shift straight back. All the gears work but you pretty much have to double clutch to shift down. Shifting up seems ok but not real pretty. Is this something common with these transmissions? I think the tranny should be rebuilt. Any ideas? What would be the cost of getting the tranny rebuilt if I pulled it out of the vehicle? Anybody do this out there?

I also want to get more power/torque out of this engine. Anyone know how much more I can get WITHOUT making major changes (like turbo, intercooler, fuel pump)? I plan on installing the standard pyrometer and boost gage. Is 1200 degrees F the max for exhaust temperature? I've heard this model doesn't have a waste gate but I don't know for sure as I didn't notice if it had one or not. Should I just start tweeking the pump adjust until it starts smoking?

Anyway, thanks from your help.

swade (lots of diesel stuff, mostly NA)

 

[Whit]

heres ome good info to get ya started

http://www.oilburners.net/forums/showthread.php?t=19958&highlight=nv4500

 

[Whit]

here is some VE pump info from my bud Cowboy Customs

Ok, this has come up quite a bit lately so I thought I would do a write up on where/how do I locate/grind/install my fuel pin?

1)Ok, looking at the Injection Pump (IP) you will see a cover attached with 4 screws, and a small circular cap in the center (smoke screw adjustment is under that small cap) and on the rear of the pump is a boost pressure line.

2)Start by removing the boost PSI line, there r 2 copper washers so be careful not to loose these!

3)Now remove the 4 screws, pull the top off.

4)You will see a rubber diaphram, this is the fuel pin, just pull it out.

5)On the fuel pin you will notice a deep, and shallow side, in stock form the shallow side will be facing toward the front of the truck.

6)Now you can either reinstall the fuel pin with the deep side facing toward the front of the truck, or make the "old smokey fuel pin."

7)Should you deside to grind the pin, just find a dremel tool or what ever you want to use, this is hardened steel so dont be afraid here, just keep a good smooth "ramp" and take it right down to whatever depth you desire, personally, just grind it down so at the neck its about 1/16 of an inch thick, this will give you the most horse power gain.
You will also need to get into the neck as far as possible, so as to keep the fuel rack from defueling when the pin is at full travel.

(With the pin removed you will see a star wheel, this is another adjustment you can make.)

8)Now reinstall your pin with the nice new cut you just made facing the front of the truck, inserting it into the tension spring and nylon washer.

9)Reinstall the cover with the 4 screws, and put the boost line back on, your done!

After about a week or so of driving with this, pull the pin and observe the "trail" the fuel rack leaves on the pin, this will tell you if you may need to do more fine tuning (grinding) on the pin.

Disclaimer: You are responsible for following this procedure, I tried the best I could to be as detailed as possible. Good luck and have fun. The whole process takes about an hour, and you WILL increase Exhaust Gas Temperature (EGT) (your adding more fuel to the fire obviously)