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Discussion Starter #1
I recently was given a Cummins 4B 3.9-G2, It is a 2001 model and states that it is for constant speed use only, prime HP 62 at 1800 rpm and Standby HP 68 at 1800 rpm. This was a generator engine that has very minimal use. It was on a generator where the generator unit went bad and they replaced the whole generator/engine setup. The engine was removed and placed in storage back in 2010. I have acquired it now and was thinking of other applications I could use this engine for. I'm kind of wide open with different ideas right now. The throttle position is wired on both side to keep it at 1800 RPM's photo 3.jpg My thought was that I could remove these wires and add a spring to make this a variable position throttle, any comments or concerns with doing this?

I have some more questions to come but I figured I would shoot one at a time.
 

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If it was me, I would seriously consider pulling that injector pump and putting a standard variable speed unit pump on. I would think that pump would be setup for fixed fueling and wouldn't take kindly to being used in a variable setup.

That's my thoughts off the bat
 

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Using the engine for its original purpose (generator) just seems boring. This thing needs some excitement built back in its life, it needs to move, not be mounted somewhere and forgot about. The 4b seems like a pretty simple engine, I can't wait to put in on a engine stand and run it.
 

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Hate to break it to you but that pump has an RS type governor. That makes it absolutely useless for just about any other application than its intended purpose. If it was an RSV you would be fine.

RS governor is for a specific RPM. You have two options, idle and full throttle. It will not be able to do anything but what its set for because the governor is too unstable between its high and low RPM setting.
 

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A huge sandblaster or air compressor or generator. Or pay the money for a new injection pump. Then add a turbo and have some fun.
 

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Sell it. Trade it for a road engine if you plan on using it in a vehicle. 62HP sux and you cant turbo it without changing out pistons and checking for piston squirters.
 

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Converting that engine to road use can be done but will involve some money. First, you need a new injection pump. If a turbo is in the thoughts, check to see if it has the piston cooling nozzles. Probably does, but if it doesn't forget it. If it can be turboed, then new pistons and rings will be in order. NA engines are higher compression than the turbo models. Of course you'd need a turbo and exhaust parts. Another item that will be different on this engine is the cam. May not have the best specs for turboing. All in all you'd probably put a few thousand in it to make it road worthy. It's only money.
 

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Discussion Starter #10
Thanks for the input on the fuel pump, I don't mind spending a little money, if I don't spend it on this I will just waste the cash on bills or something silly like that. Chasing women and wrenching doesn't seem like the worst habit one can have. I think I want to keep it non turbo, at least for a while. Heck, those old military jeeps with the go devil engines only had about 60 to 75 hp.
 
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