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Old 09-13-2021, 12:31 AM   #1
Wildstreak
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Cummins conversion questions

What fuel pump would you recommend for the 5.9 cummins conversion with factory dual saddle tanks? Im trying to gather all the parts needed for the swap before I begin.
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Old 09-13-2021, 07:55 AM   #2
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Re: Cummins conversion questions

Check out this website for fuel consumption rates for a diesel engine. Based on these charts, even a 1000-hp diesel can be fed from a common 255 liter-per-hour pump.

The Walbro 255 is often installed in these squarebody tanks, but I don't know if it can handle diesel fuel. I assume it can, but research that first.

https://barringtondieselclub.co.za/t...nsumption.html
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Old 09-13-2021, 08:27 AM   #3
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Re: Cummins conversion questions

What did the Dodge trucks use for a fuel pump? I wouldn't think it would be in tank but I really don't know. I have always wanted to do this swap though.
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Old 09-13-2021, 09:58 AM   #4
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Re: Cummins conversion questions

Which Cummins are you using? 5.9 or 6.7? If 5.9, is it 12v? 24v? CR? What modifications? Intended usage? Lots more information needed
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Old 09-13-2021, 01:21 PM   #5
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Re: Cummins conversion questions

Iíve done 2 conversions a 4bt and.a 6bt both mech type engines.

make sure you read up on which style of lift pump you mate to which injection pump, the wrong one can either burn the injection pump up, or blow the seals out of it.

This is related to the p7100 and the rotary ve pump, not the electronic engines
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Old 09-13-2021, 08:07 PM   #6
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Re: Cummins conversion questions

My 95 12valve P pump ran like a scalded dog with is factory mechanical lift pump. If i was doing the swap to keep it simple i would run the mechanical lift pump on the engine and make sure to remove the in-tank sock or put 6.2 sending uninits in your tanks.

I am assuming your running a 12 valve 5.9 with a p7100 pump. Are you running different turbo? Turbos? Auto or manual trans?

Lots of factors could change what fuel pump would be ideal.
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Old 09-13-2021, 09:12 PM   #7
Wildstreak
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Re: Cummins conversion questions

Quote:
Originally Posted by 84 400 View Post
My 95 12valve P pump ran like a scalded dog with is factory mechanical lift pump. If i was doing the swap to keep it simple i would run the mechanical lift pump on the engine and make sure to remove the in-tank sock or put 6.2 sending uninits in your tanks.

I am assuming your running a 12 valve 5.9 with a p7100 pump. Are you running different turbo? Turbos? Auto or manual trans?

Lots of factors could change what fuel pump would be ideal.
12v 5.9 with a nv4500 stock turbo with intercooler. Just started doing research late last night so Im really green with very little knowledge on the swap.
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57 chevy 4x4
70 swb fleetside 4x4
68 burb 2wd:
71 burb 2wd: 350 4spd
71 lwb fleetside 4x4: 350/sm465/205/3.07 eaton posi rear
72 lwb fleetside Cheyenne 454/th400
1991 GMC V3500 CC 4x4
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Old 09-13-2021, 09:53 PM   #8
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Re: Cummins conversion questions

Quote:
Originally Posted by 84 400 View Post
My 95 12valve P pump ran like a scalded dog with is factory mechanical lift pump. If i was doing the swap to keep it simple i would run the mechanical lift pump on the engine and make sure to remove the in-tank sock or put 6.2 sending uninits in your tanks.

I am assuming your running a 12 valve 5.9 with a p7100 pump. Are you running different turbo? Turbos? Auto or manual trans?

Lots of factors could change what fuel pump would be ideal.
alright I was confused I didnt know there was a lift pump on the motor , this diesel thing is a whole new ball park for me, I just got a complete truck and want to swap the engine and tranny into my 88
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57 chevy 4x4
70 swb fleetside 4x4
68 burb 2wd:
71 burb 2wd: 350 4spd
71 lwb fleetside 4x4: 350/sm465/205/3.07 eaton posi rear
72 lwb fleetside Cheyenne 454/th400
1991 GMC V3500 CC 4x4
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Old 09-13-2021, 10:20 PM   #9
ky-donzi
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Re: Cummins conversion questions

You have a great platform to start with.

If itís a 4x4 Chevy your swapping into the hardest item will be finding a pass side drop transfercase to adapt to your nv4500...

Like 84 400 said, get rid on the in tank fuel sock, and do yourself a favor and replace all the rubber link fuel hoses along the frame, air leaks will drive you insane later
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Old 09-13-2021, 10:33 PM   #10
Wildstreak
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Re: Cummins conversion questions

Quote:
Originally Posted by ky-donzi View Post
You have a great platform to start with.

If itís a 4x4 Chevy your swapping into the hardest item will be finding a pass side drop transfercase to adapt to your nv4500...

Like 84 400 said, get rid on the in tank fuel sock, and do yourself a favor and replace all the rubber link fuel hoses along the frame, air leaks will drive you insane later
the truck its going into is a 88 3+3 1ton 4x4, it has a 454 th400 np205. I found a kit to adapt the np205 to the nv4500 from advanced adapters. Im just starting to piece everything together.
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57 chevy 4x4
70 swb fleetside 4x4
68 burb 2wd:
71 burb 2wd: 350 4spd
71 lwb fleetside 4x4: 350/sm465/205/3.07 eaton posi rear
72 lwb fleetside Cheyenne 454/th400
1991 GMC V3500 CC 4x4
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Old 09-13-2021, 11:20 PM   #11
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Re: Cummins conversion questions

Quote:
Originally Posted by Wildstreak View Post
the truck its going into is a 88 3+3 1ton 4x4, it has a 454 th400 np205. I found a kit to adapt the np205 to the nv4500 from advanced adapters. Im just starting to piece everything together.
Be aware that your Cummins nv4500 has a different output shaft(29-spline) than a GM nv4500(32-spline).

Another option to consider is to find a transfer case from a first-gen Cummins truck(pre-1994). Those were a passenger side drop, and should bolt right up to your transmission.
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Old 09-15-2021, 10:43 AM   #12
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Re: Cummins conversion questions

I would use the stock type lift pump especially if you want to retain dual tanks. I'd strongly recommend not installing an electric type lift pump over that piston type lift pump. (Assuming this is a P-pump 12v) Also, there is a diesel conversion section in the engine area on this forum. There's a lot of good info in there about these swaps.
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Old 09-17-2021, 09:46 PM   #13
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Re: Cummins conversion questions

stock lift pump works for me for the last 10 or so years. fully built and flowed 215 pump.
dodge nv4500 with a chevy mainshaft, to a chevy 205 is a good way to go.
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Old 09-19-2021, 08:47 PM   #14
Wildstreak
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Re: Cummins conversion questions

Ok next question, will I have to cut the firewall at all?
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70 swb fleetside 4x4
68 burb 2wd:
71 burb 2wd: 350 4spd
71 lwb fleetside 4x4: 350/sm465/205/3.07 eaton posi rear
72 lwb fleetside Cheyenne 454/th400
1991 GMC V3500 CC 4x4
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Old 09-20-2021, 10:05 AM   #15
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Re: Cummins conversion questions

no cutting but I do bend the firewall flange in where two of the bellhousing bolts tend to hit.
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