81 Chevy Cummins swap 90% complete

Hey everyone. It's been a while since my last post. I work off shore and have little time to work on the truck. In case you guys don't remember, I have a 1981 Chevy short bed 2wd pickup. I installed a 1995 Cummins, NV4500 trans, 5x12 injectors, #5 fuel plate, 181 delivery valves, soft AFC spring set, Mack plug, 60# valve springs, 4000 GSK, ATS 3 piece manifold and s362/s475 compound turbo setup along with a 5" straight piped exhaust system. I went with an air to water inter cooler simply because it involved no cutting to the truck (I originally planed on running an air to air inter cooler I modified). I got the thing almost finished up. I actually moved it under it's own power for the first time today (Idled it around for a second). I'll post pictures tomorrow. I have a question for you Cummins swap guys. I am not sure how I want to go with the throttle. The throttle is backwards from the gas engine. Meaning that I need to press the lever toward the radiator to increase throttle where as the gas engines throttle open by pulling the lever toward the firewall. I'm sure there is something missing from the throttle assy but I am having a heck of a time finding pictures of what it should look like. Does anyone have a good clear picture of the throttle assy of a 12v Cummins? Or perhaps have the parts I'm missing. I am missing everything pretty much. My fuel pump has only the lever on the pump itself. It is drilled and tapped for something to attach there but I'm not sure what. I have no linkage at all. I want to figure out what I'm missing to see if I will be able to adapt my factory throttle cable to it or if I'll have to go another route. ANY help would be appreciated. Here are a few old pics of the build, but I'll get updated pics to you tomorrow. Thanks again for any help you can provide.

WOW! Looks good.

Very,very nice set up:rockwoot:

On the 81 built the factory pedal and throtle pedal worked perfect and was the correct length. But I had to use the auto tranny part on the inj. pump so it pulled back rather than forward like you were saying. Sounds like you prob. dont have this part and will need to find one, it will be easy to hook up once you do. Ryan

Can't you just build a "tab" to bolt to the factory lever on the pump that points down instead of up, that way you have to pull instead of push?

At least I think I remember what a p-pump has?
Chris

Thanks for the kind words. It's been a long process for quite a few reasons. For one the first engine was in the back of a buddies truck when it was stolen and then wrecked (The Cummins was never recovered). So this is the replacement. It takes time to find a good deal, especially when your looking to save a few dollars. then I work off shore so I'm gone for a month at a time. but it's finally comming together. For the first time in a long time, I'm excited.

stock600 said:

On the 81 built the factory pedal and throtle pedal worked perfect and was the correct length. But I had to use the auto tranny part on the inj. pump so it pulled back rather than forward like you were saying. Sounds like you prob. dont have this part and will need to find one, it will be easy to hook up once you do. Ryan

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That sounds like exactly the part I need. I'll keep an eye on eBay and call the local wreckers tomorrow. Someone has to have one. If anyone has one they can spare please P.M. me. I'd we happy to pay for it.

Signature600 said:

Can't you just build a "tab" to bolt to the factory lever on the pump that points down instead of up, that way you have to pull instead of push?

At least I think I remember what a p-pump has?
Chris

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Well that was my thought also. If I can not find some type of factory part I'll end up doing just this. A simple bolt on would be nice, but a custom fabbed piece would probably be cooler. I'll do some looking tomorrow and see what I come up with. If I can't find anything in the next few days I'll probably end up building something. Thanks for the suggestions. I'll keep you guys updated.

Have any more pictures of the truck?

DWitcher said:

Have any more pictures of the truck?

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Yes I do. My cameras batteries died in the middle of taking pics this afternoon, so I can't upload them to my computer just yet. I'll be pickup some batteries tomorow morning and I'll post a few pics then.

Did you eliminate the heater box? If so whats your plans for A/C and heater?

The part I was talking about is called the throttle position sensor on a graph I just seen. You'll have to have it and the adjustable rod that goes back to the fuel lever. There's a picture of this over in a thread called like: "not fueling hard enough any more" in the comp. and performance portion of this forum. Other ways of doing it for sure but if you can locate these factory bolt on parts then it will be a breeze to hook up and look factory. Ryan

DWitcher said:

Did you eliminate the heater box? If so whats your plans for A/C and heater?

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Well, I eliminated the A?C box. I don't care much for AC, besides the compound turbo piping would have been a headache to fit around the A/C, but I do need heat. I will be installing a heater box from a truck that came without A/C. It is much smaller and easier to squeeze in.

stock600 said:

The part I was talking about is called the throttle position sensor on a graph I just seen. You'll have to have it and the adjustable rod that goes back to the fuel lever. There's a picture of this over in a thread called like: "not fueling hard enough any more" in the comp. and performance portion of this forum. Other ways of doing it for sure but if you can locate these factory bolt on parts then it will be a breeze to hook up and look factory. Ryan

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I took a look over at that thread. That is a little more involved then I thought it would be. That has a linkage going up toward the front of the engine and then you have th stretch a throttle cable all the way up there. Thanks for the info though. After looking at that pic I have decided to just build a bracket. It's almost finished, it is just a simple bracket that bolts to the pump lever and points down rather then up. It will allow the throttle to be pulled toward the firewall. I have to get some batteries for my camera, but when I do I'll post some pictures of the trucks progress and the bracket I'm building. Thanks again for the help. This site is awesome

The A/C box from the late 80's early 90's S-10 is low pro and with a little mod fits real well in your body style.

DWitcher said:

The A/C box from the late 80's early 90's S-10 is low pro and with a little mod fits real well in your body style.

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Thank you. I'l have to look into that. Sounds like a good idea.

TheSh111t said:

Well, I eliminated the A?C box. I don't care much for AC, besides the compound turbo piping would have been a headache to fit around the A/C, but I do need heat. I will be installing a heater box from a truck that came without A/C. It is much smaller and easier to squeeze in.

I took a look over at that thread. That is a little more involved then I thought it would be. That has a linkage going up toward the front of the engine and then you have th stretch a throttle cable all the way up there. Thanks for the info though. After looking at that pic I have decided to just build a bracket. It's almost finished, it is just a simple bracket that bolts to the pump lever and points down rather then up. It will allow the throttle to be pulled toward the firewall. I have to get some batteries for my camera, but when I do I'll post some pictures of the trucks progress and the bracket I'm building. Thanks again for the help. This site is awesome

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Making a braket will prob. be much faster than finding the Cummins parts for sure, but the factory cable that came in my 81 reached all the way up to that front TPS bracket perfectly, even the end that was on the cable worked out well, only a shouldered bolt and lock nut was needed. I lengthed the bottom of the lever and tried that route my new toy and didnt like the geometry and the way it piviot'ed, ended up with a push/pull cable and looped back up from the front to get a pull in the right direction, it works well in this case. Good luck on the build, I miss my truck it was a Caddy on the drag strip. Ryan

Yeah, I ended up just making a simple bracket. I got the stock cable to reach. Now I just need to figure out how to hold the cable. It is attatched to the throttle bracket, but the rest of the cable is just hanging in mid air. I need something to hold the cable in place to that it will be able to pull the throttle rather then just flop around under the hood. I'll figure out something this afternoon.

Sounds like a fun swap...

I plan on doing the same swap but in an 85 K10, do I need to swap the front axle, the guys at 4btswaps.com won't give me a straight answer. Or would it be cheaper to get one of those retired military trucks?

dekocards90 said:

I plan on doing the same swap but in an 85 K10, do I need to swap the front axle, the guys at 4btswaps.com won't give me a straight answer. Or would it be cheaper to get one of those retired military trucks?

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I;m not sure if you will need to swap axles or not. I went to 1 ton front end parts, bue my truck is a 2 wheel drive. I'm not sure how much weight your 4x4's front end can hold. The big thing to thing about is the torque output of the Cummins. In stock form they are fairly stout, but once modified the torque numbers get crazy. What are your plans for the engine, and for the truck?

To pull, and daily driver. I plan to do a single turbo though for regulation reasons and eventually to an engine rebuild down the road. A dana44 front in my opinion needs to be replaced with the 60. It's an automatic so I will have to drill a whole in the floor and put a 6 speed in.

What axle is in the rear? I have never seen (Not to say they didn't make any) any Blazers with full floating 14 bolt rearends. Does it have a 14 bolt in it at all? I assume so, but I would bet it is the smaller semi floating 14 bolt. If this is the case, you will definatly need to swap that ot before you add a modified Cummins. The full floating 14 bolt uses a 10.5" ring gear, and 1.5" axles. They are about as strong as a dana 70 (Some people claim they are a little stronger then the 70 but all agree they are NOT as strong as the Dana 80) while the semi floating 14 bolt uses a 9.5" ring gear and smaller axles. Besides the fact that they are a semi floating diff, so if you do end up breaking an axle, you'll be loosing thay wheel along with it. Just something to think about.