92 cummins to chev conversion questions

[Sea01Cummer]

I have done some reading here and understand you can get the chev bellhousing adapter from cummins , anyone know how much, the swaps i have seen were using a auto , i want to use a standard, what flywheel clutch combo would work with the chev standard transmission, i am going to find a mid 80s 3/4 ton 4x4 to do the conversion, any help cost estomates would be helpful. I already have the 92 engine.



Steve

 

[JUeckert]

atkins,i hope you have better luck getting a answer to this guestion than i did. for over a month i have made a few post on this as well as other web sites,includeing ford and gm,thus for i have recieved no replies. my project will take place in late winter,simply because i wont have time till then,so i have not seriously pursued getting a answer. i already have the donor,a 95 ford school bus with a 5. 9 and a allision. i intend on installing the 5. 9 and allision in a 84 chev 1 ton 2wd. its got a bad gas eng in it . anyway the only thing i can offer you as for info,is this . seems a while back i caught the tail end of a guy on the gm web site that did a conversion on a truck like you have,he mentioned that a slight body lift made the 5. 9 fit in the truck better,if not mistaken he had to use a lift to make it work,not positive. this is about all the info i can pass,if i find more i will post,if you find a info source please post as well...

 

[Sea01Cummer]

I was really hoping to have some info by now, i really want to use the standard but if i can't find a flywheel i guess i'll go the turbo 400 route, they stand up to hot rod cars i hope they will handle a stock 5. 9, if you hear anything let me know and i will do the same.



Steve

 

[McCRam]

If you want a manual, would you be willing to put in a nv4500, or 5600? That would make it easier. If not what other transmission do you want to use? I've always wanted to convert a chev four door. When I get to do this I plan on using the 5600 for simplicity's sake. And parts will be easier to find if it breaks.

 

[T. Baker]

$ 400 for flywheel starter bell housing adaptor etc for GM 4 speed or auto:

The Diesel Depot

800-553-8192



Thats what I used in my conversion.

 

[Sea01Cummer]

That's just what i was looking for, the 5600 cost like 2000 plus core , the 4500 cost 1000 lpus core, that was the delema, Baker what clutch are you using and what trans ?





Steve

 

[NIsaacs]

SAtkins, Cummins sells the chevy adapter/flywheel combo that you are asking about. It will fit the stock 4-speed w/stock 12"x11/8x10 spline input shaft. However without an overdrive, you will be geared too slow, with the low rpm of the Cummins. You will need to change out the axle gears to about 3. 00 ratio to make a highway rig. What do you indend to use the truck for? I used the above combo, in a Ford conversion, with the 280vo Clark 5-spd, chevy case & input shaft. I did the coversion in 1990, so transmission choice was limited. There are more & better choices for tranys now. If you are going to tow with the truck, the 12" clutch is a little light. With my power output and towing heavy, I twist the center out of the clutch plate. I have had no trouble with the clamping force of the stock diapham cover. I ordered a new High performance Spec clutch plate from Heath Diesel, but I haven't installed it yet. One other thing I run into with the adapter, is that for some reason it is designed to rotate the engine to the right side. I mounted my engine straight up, and rotated the transmission instead.



If you have more questions, please feel free to ask





"IF IT AIN'T CUMMINS POWERED, IT AIN'T A TRUCK"





"NICK"

 

[T. Baker]

I ended up splitting the side twist between the engine and the transmission so that there is a slight tilt to both - not very noticable.

I too twisted out the center of my first clutch. I bought a very high clamping force pressure plate and the clutch center looked like cintered metel. I replaced it with an off the shelf truck 454 clutch and I'm much happier with that. It will slip at about 600 or 700 lb-ft of torqe which is fine with me. I feel lucky I didn't rip the input shaft in two. After ripping the center out of the clutch I detuned my enging and put the torque plate back in the pump. 1000 lb-ft or torque is just too much!

I am running an advanced adaptors overdrive . 73 overdrive into a '66 chevy SM420 into a dana 300 transfer case into a dana 44 rear end with 2. 72 gears which = 70 mph at 1,500 RPM. So far no trouble with the dana 44 rear end despite what everyone told me but my truck only weighs 5K lbs. Also 2. 72 gears are the strongest of them all.



Before I put the torque plate back in and I had 3. 73 gears I could pretty much out run almost every one in 4th gear from about 30 mph up. I would get pesky people in new SUV's etc the would try to pass me on the right side just because my truck looks slow. It was so fun to blow them off! Those days are over though because I know this engine can tear my drive line up and I don't want to do any more emergency clutch jobs away from home. What a PIA. I had to replace the clutch at my cousins house in LA with very few tools and the transmission,"T" case, and over drive weigh a zillion lbs. Aslo I know the 1" and an eighth input shaft can be ripped in two. I'm suprised it didn't happen. That is why I suggest a stock 454 truck clutch because it will help protect the input shaft. If it slips you can hear it and just back off the throttle a little.

 

[MRowe]

I put an 89 5. 9 into a 93 Gmc 3500hd 2wd car carrier using the dodge bellhousing, clutch, flywheel and a nv4500 transmission. had to make plates to lower the motor mounts and a few other "adjustments but it was well worth the trouble.

 

[Sea01Cummer]

You guys have given me just what i wanted, i am going to call cummins on monday and get some prices, anyone happen to still have the part numbers for the adapter and flywheel, this really is going to cut the cost way down, regearing the truck is no big deal to me, i'm a ag mechanic for Deere, in you guys opinion what would be the right gear ratio using the gm 4 speed, i will pull on ocasion but only 3-4 horses, also you guys who have this setup what kind of milage are you getting.





Thanks Steve

 

[NIsaacs]

The gear ratio is kinda a personal preference, based on what your needs/wants are. I prefer to gear fast (mph), run slow (rpm), on the Cummins. I would say no slower than a 3. 00 with the 4-spd, also depends on the tire size you want/like. The "92" engine you are using is tached out at 2500 rpm, you will probably want to turn that up some. The stock HP rating is kinda disappointing, so be prepaired to pump it up. The mods are easy and cheap to do with excellent results. Since you will probably be using the 14-bolt rear axle, (an excellent unit) you might be limited in your ratio choice. The mid "80's" Chevy 4x4 will probably weigh about 6,000lbs with the Cummins, so 20mpg is not out of reason. I only get about 16mpg with my Ford, but it weighs 8500 lbs.





"NICK"

 

[Sea01Cummer]

the higher gearing is probablt not all that noticable because the older 4 speeds had pretty low 1st and 2nd, so i hope i will have the best of both worlds low bottom gearing and low rpm in 4th gear at cruising speed.



Steve

 

[MRowe]

For my truck i purchased a used 93 Dodge transmission with bell housing, flywheel, clutch&

pressure plate. I used the clutch and plate for core credit. I bought a new adapter plate from Dodge for a 93. The NV4500 is an od transmission and works well for my use, however with the cummins the truck has a lower top speed than the GM 6. 5 due to rev limits but the low end torque more than offsets ther overall time spent on the road. One of the problems I encountered using the standard transmission was the length of the six cylinder engine in a bay designed for a v8. I found I had to install the engine, then the adapter, the flywheel and clutch, the bell housing, and then the trans. As my truck weighs 12500 empty I am getting 13 mpg 2more than the 6. 5. Hang in there its alot of work to make a truck out of a Chevrolet Mike in VT.

 

[T. Baker]

Why would you call cummins when I gave you the phone # for the used ones at very reasonable prices? I hope you are standing over a nice soft carpet when Cummins quotes you a price :-laf



If I hadn't of had the overdrive sitting around and the transmission I would probably have gone with a NV4500. Once you repair that stupid 5 gear problem with a new main shaft it is a stronger set up the the GM transmission mostly because of the bigger input shaft. It is also much easier to get the adaptors for the NV4500.



I spent a lot of time dial indicating and re driling the dowel holes on my bell housing to get it lined up nice and true.