Cummins conversion questions

[Wildstreak]

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.

[kipps]

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

[cadillac_al]

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.

[44th Miss Inf]

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

[ky-donzi]

I’ve 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

[84 400]

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.

[Wildstreak]

Originally Posted by 84 400

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.

[Wildstreak]

Originally Posted by 84 400

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

[ky-donzi]

You have a great platform to start with.

If it’s 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

[Wildstreak]

Originally Posted by ky-donzi

You have a great platform to start with.

If it’s 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.

[kipps]

Originally Posted by Wildstreak

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.

[Dieselwrencher]

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.

[v30crewcab]

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.

[Wildstreak]

Ok next question, will I have to cut the firewall at all?

[v30crewcab]

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

[Wildstreak]

Ok I have another question. On the squarebodies do I have to cut the crossmember under the original motor out for the cummins to fit?

[44th Miss Inf]

Originally Posted by Wildstreak

Ok I have another question. On the squarebodies do I have to cut the crossmember under the original motor out for the cummins to fit?

Everyone I have done, I removed (and replaced) the GM crossmember. You have to, to get the engine low enough to keep the drivetrain in alignment.

[Wildstreak]

ok its cut out and a new one if being fabbed.

Next question. How does one hook up a tach to the the diesel? Do I need that fancy autometer gauge?

[ky-donzi]

Depends on the thickness your trans adapter, but on mine I drilled and tapped the adapter for fitting a Hall effect sensor and it counted the flywheel teeth as they came by. Then I entered the tooth count equaling one revolution into a Dakota digital tach box that sent a signal to a standard tach

[Dead Parrot]

Over on the CUCV section of Steel Soldiers, there is mention that some alternators have a tach signal post that folks have used.

[Wildstreak]

Another question for you all. What did you guys do with fuel lines to the tank? Will rubber hose and hose clamps work or no? Im also not sure which line is the return and which is the intake and help there would be amazing!

[Wildstreak]

I have the truck running and driving now. But now I have a problem with my fuel line, the fuel line is collapsing while driving. I found out I bought regular fuel line and not diesel rated fuel lines so that might be one of the problems. But Im curious. I removed the sock from the gas sending unit and I was wondering if that could be causing the vacuum problem. Could it be the pickup not drawing fuel fast enough creating vacuum??