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Vintage Diesel and Oil Engines Fairbanks Morse, Lister, Petter, Witte and other pump injected Diesel oil engines.

Vintage Diesel and Oil Engines

GM 3-71 Injectors


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  #11  
Old 11-12-2018, 12:36:38 PM
The Diesel Doctor The Diesel Doctor is offline
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Default Re: GM 3-71 injectors

Your 70 and HV injector pop at 500 PSI The HN`s pop at 3000 PSI. Better atomization and a clean exhaust. AL
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  #12  
Old 11-12-2018, 12:58:25 PM
glennh glennh is offline
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Default Re: GM 3-71 Injectors

Thanks for all the feedback. I'll check the suggested sources and let everyone know when it's up and running. I should have time to get the oil changed and the fuel system flushed while I wait for injectors. Already got it cranking with the starter (no injectors), and it pumped decent looking oil out the pressure gage line.
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Old 11-12-2018, 02:06:46 PM
glennh glennh is offline
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Default Re: GM 3-71 Injectors

So, one more quick question before I buy injectors. I pulled the air intake to see what kind of condition the blower is in and this is what I found.Click image for larger version

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I assume that some of this oil is coming from the air filter, as the whole tube from the filter to the blower is coated with oil, but some of it must be coming from the blower, right? I also see several significant gouges in the lobe seals. Is this engine going to be worth putting money into, or should I find a newer 3-71 or 4-71?
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  #14  
Old 11-12-2018, 03:14:33 PM
Mark Schneider Mark Schneider is online now
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Default Re: GM 3-71 Injectors

I rebuilt an ancient 6-71 crusher engine awhile back and the view in the blower box was very similar. The edges of the box look gritty which more than likely means the fine sand got pulled through the oil bath air cleaner. Your next move should be to remove the oval air box covers and do a visual on the innards. If there is a build up of oil and fine sand (resembling asphalt) on the bottom of the air box the liners and pistons will be toast. As you turn the engine over you will be able to see the compression rings go by the ports. If the rings appear to be sloppy in the grooves an overhaul will be needed.

The crusher engine I did had dual oil bath air filters and the bottom of the air box had a thick layer of that petrified oil/sand mix. I chiseled and pressure washed for hours trying to get that stuff out. Needless to say when I finished the rebuild the first thing I did was toss the original oil bath air filters in the junkpile and mounted a big paper element filter assembly off of a combine.
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Old 11-12-2018, 06:13:26 PM
Anthony60 Anthony60 is offline
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Default Re: GM 3-71 Injectors

Greetings Glen.
Looks like you have lots of good help here! Just putting my 2 cents worth, with the HV injectors, they have a more likelyhood of light smoke hazing. Back in the day I rebuilt 100's of inline 71's for the oilfields, 6-71's we kept them 2 valve heads(2 valve heads rarely dropped valves like the 4 valve heads) we would build them up with 4 valve cylinder kits and run offset N injectors they ran strong and clean...
I would recommend running N60's with an injector timing height of 1.460, this will run nice and clean. But with the offset N injectors you will need to replace the injector hold down clamps and fuel jumper lines as well.
I have manuals I can look up any other info you might have.

Quote:
Originally Posted by glennh View Post
So, one more quick question before I buy injectors. I pulled the air intake to see what kind of condition the blower is in and this is what I found.Attachment 322733

Attachment 322734

I assume that some of this oil is coming from the air filter, as the whole tube from the filter to the blower is coated with oil, but some of it must be coming from the blower, right? I also see several significant gouges in the lobe seals. Is this engine going to be worth putting money into, or should I find a newer 3-71 or 4-71?
Blower Looks pretty normal for a high hour engine
The 'Grit' in the air box is mostly oily carbon and not dirt (the Joy's of a 2 stroke ported diesel). As long as the blower turns free without dragging sounds it still is runable. What you don't want to see a a completely oil washed set of rotors, that would mean blower seals, piston rings or piston pin retainers leaking. Keep in mind that they aren't called Driptroits for nuthing�� they are always going to slobber some oil out the drain tubes.
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  #16  
Old 11-12-2018, 09:26:51 PM
The Diesel Doctor The Diesel Doctor is offline
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Default Re: GM 3-71 Injectors

What are the model and S/N of your 3-71? From the looks of the oil bath air cleaner, starter, generator, and oil filters i would guess the middle 40s. The off set injector will not fit in the two valve head because of interference with the valve springs. I agree with Anthony 60 on the blower. With the battery disconnected, you can push on the blower rotors and they should move slightly and spring back. When blower lobes touch you know it and their will be polished surfaces on them. AL
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Old 11-12-2018, 09:50:41 PM
glennh glennh is offline
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Default Re: GM 3-71 Injectors

Model 371RC-6

Serial 3716568
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  #18  
Old 11-12-2018, 11:19:44 PM
The Diesel Doctor The Diesel Doctor is offline
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Default Re: GM 3-71 Injectors

According to your S/N it was the [7586] 3-71 built. My data book goer back to 1972 and shows the first 3-71 to be built in 1972 was SN 79536 and starting in 1993 102396 had been made. KTRON might be able to find more info on this and enlighten us. AL

Getting old, meant to say your engine was the 6568 3-71 to be built.
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Old 11-13-2018, 04:54:01 PM
Anthony60 Anthony60 is offline
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Default Re: GM 3-71 Injectors

Quote:
Originally Posted by The Diesel Doctor View Post
What are the model and S/N of your 3-71? From the looks of the oil bath air cleaner, starter, generator, and oil filters i would guess the middle 40s. The off set injector will not fit in the two valve head because of interference with the valve springs. I agree with Anthony 60 on the blower. With the battery disconnected, you can push on the blower rotors and they should move slightly and spring back. When blower lobes touch you know it and their will be polished surfaces on them.
AL
DR DIESEL, Its been a long time but I do remember running N65 injectors in those old 6-71s, I may be wrong
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  #20  
Old 11-13-2018, 09:41:06 PM
The Diesel Doctor The Diesel Doctor is offline
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Default Re: GM 3-71 Injectors

Anthony60, If your inline 6-71 had a four valve head a N65 would fit in the injector tube. If the engine has a two valve head it wouldn`t Before HN injectors were available i took HV injector bodies and machined and lapped them to the dimensions of my N 60 bodies. Transferred the N parts to my straight bodies They were in in a 4-71 and they worked. AL
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