K30 Downgrade to Cummins Project

[Vintage Windmills]

This is about a 1986 K30 crew cab that I bought out in Seattle. I have not personally seen the truck yet. I did thorough recon though I bought since I think its probably the simplest way to get a cummins powered 4x4 chevy. This truck is rust free or close to. I am going to plan this awhile and not do any wrenching on the truck until its ready to go, unless I just replace the trans for now.

Plan was to pull the engine and put in a Cummins. I think I will do that for efficiency, even if its a step down in power It will be unless I turn up the cummins. After I agreed to purchase, he provided Dyno sheets proving it has 575 ft lbs and 475 HP. The trans is blown, can you believe it?? The debate I'm having with myself is if I should go fuel injection and overdrive and keep the 502. I think the fact that the BBC is built for 91+ octane will be the determining factor to go with the 1990 6BT/G360/NP205 in the shed I'm tripping over.

Pics and description of purchase procedure to follow. It was quite a process to buy it and get it lined up for shipping

[Dieselwrencher]

475hp and spark plugs plus towing equals stop at every gas station.

[ryanroo]

oh i bet that would be a FUN motor it a shorter truck, something a little more nimble.

i would say a 6bt is using the truck better. it can be added to over time to increase the power if you find yourself looking for more black smoke.

[burnin oil]

The Cummins will definatly be the way to go. The only thing bad is the rotary pump. I will never make the power of BB horse power wise. Swapping to a p7100 pump will let you. Either way you should easily have more torque than the big block. Just don't forget that the Cummins is heavier so you will need to build a little more torque to motivate it. My 700HP 12v got 18.5 MPG driving in traffic.

[ryanroo]

Originally Posted by burnin oil

The only thing bad is the rotary pump.

why is this bad? sure, a ppump will make bigger numbers, but if you are trying to work in the >400hp range, it will be great. the VE pump offers some nice things that the 7100 does not. i am betting Jud is not looking to make a magazine truck, but more a usable old chevy that is kind of cool to boot. the ve motor is a great way to do that. 350-400 HP with the torque numbers a 6bt will put down with that HP is more than enough to make a guy smile when he pushes the skinny pedal.

[burnin oil]

Originally Posted by ryanroo

why is this bad? sure, a ppump will make bigger numbers, but if you are trying to work in the >400hp range, it will be great. the VE pump offers some nice things that the 7100 does not. i am betting Jud is not looking to make a magazine truck, but more a usable old chevy that is kind of cool to boot. the ve motor is a great way to do that. 350-400 HP with the torque numbers a 6bt will put down with that HP is more than enough to make a guy smile when he pushes the skinny pedal.

My next sentance said it all. The rotary will run out of umph before making the power of the big block HP wise. Now if the OP isn't trying to match the power output of the 502 and just wants the torque then the rotary pump will function very well for him. Rotarys are great for mild setups but injector selection is limited. The 7100 just has alot more parts available to go nuts with. Torque on a 12v tends to be 1.5-2 times the HP so a good 350 HP setup should yank 14000lbs through the mountains pretty well. I didn't mean to upset anyone about the rotary pumps and was only trying to say it would run shy trying to match the HP of the 502. Obviously the torque would be alot healthier than the gasser. I definatly agree that the static timing of the 7100 is its weakness.

[Vintage Windmills]

Originally Posted by burnin oil

Now if the OP isn't trying to match the power output of the 502 and just wants the torque then the rotary pump will function very well for him.

Yep, don't need to match the 502 power wise, just need enough to get up big hills,mountains decent speed while towing 14k.

[Dieselwrencher]

Originally Posted by burnin oil

My next sentance said it all. The rotary will run out of umph before making the power of the big block HP wise. Now if the OP isn't trying to match the power output of the 502 and just wants the torque then the rotary pump will function very well for him. Rotarys are great for mild setups but injector selection is limited. The 7100 just has alot more parts available to go nuts with. Torque on a 12v tends to be 1.5-2 times the HP so a good 350 HP setup should yank 14000lbs through the mountains pretty well. I didn't mean to upset anyone about the rotary pumps and was only trying to say it would run shy trying to match the HP of the 502. Obviously the torque would be alot healthier than the gasser. I definatly agree that the static timing of the 7100 is its weakness.

No one was up set. Just trying to make sure people can have a better idea of what these are capable of. The best set up would be a variable timing P-pump but then the simplicity would be out the window.

[burnin oil]

I wouldnt worry about the frame to much. It could always be boxed to help support the power output. I would worry about spring wrap and rearends giving up the ghost. Somehow the Dodge spring packs worked pretty well, even with those monster lift blocks.

Originally Posted by Dieselwrencher

No one was up set. Just trying to make sure people can have a better idea of what these are capable of. The best set up would be a variable timing P-pump but then the simplicity would be out the window.

Mack had a variable timing setup at one point that someone was tinkering with. I dont know if they ever got it running. I think it was a 7100 on a 673 motor. It was an unusual combo that didnt run the normal Bosch inline pump.

[patdaly]

Yep, the dynamic timing of the VE is a definite plus, not to mention it should get a tick better mileage and start instantly....... I have the VE on my 4BT and the P7100 on my 6, hard to see any advantage of the P7100 until you get well past reasonable HP numbers.

[Vintage Windmills]

Originally Posted by Dieselwrencher

475hp and spark plugs plus towing equals stop at every gas station.

Yep, but $3 gas and $4 diesel does make a guy do the math

Originally Posted by ryanroo

oh i bet that would be a FUN motor it a shorter truck, something a little more nimble.

i would say a 6bt is using the truck better.

I think you're right, this will be a tow rig, going to the remote western US so towing efficiency is paramount. Will also be a pain to find 91 octane in MT and other western states.

Originally Posted by burnin oil

The Cummins will definatly be the way to go. The only thing bad is the rotary pump. I will never make the power of BB horse power wise. Swapping to a p7100 pump will let you. Either way you should easily have more torque than the big block. Just don't forget that the Cummins is heavier so you will need to build a little more torque to motivate it. My 700HP 12v got 18.5 MPG driving in traffic.

Cool, I'm not after crazy HP, just enough torque to get through the mountains at speeds of 40mph or greater while pulling 14,000 lbs.

Originally Posted by ryanroo

i am betting Jud is not looking to make a magazine truck, but more a usable old chevy that is kind of cool to boot. the ve motor is a great way to do that. 350-400 HP with the torque numbers a 6bt will put down with that HP is more than enough to make a guy smile when he pushes the skinny pedal.

Indeed, I'm saving the show quality effort and $ for the older K20's. THis is just the quickest way to get a tow rig capable of pulling 16000 lbs reliably and safely. Trucks already got airbags and hydroboost!! I pretty much like it the way it looks now (stockish, unmolested, nicely aged). Running boards have to go though!!

Originally Posted by patdaly

Yep, the dynamic timing of the VE is a definite plus, not to mention it should get a tick better mileage and start instantly....... I have the VE on my 4BT and the P7100 on my 6, hard to see any advantage of the P7100 until you get well past reasonable HP numbers.

Effieciency is more important to me than crazy power.

[ryanroo]

Originally Posted by Vintage Windmills

Running boards have to go though!!

Thanks goodness. i love that thing, outside of the old man running boards.

i keep looking for one of these to do myself. unfortunately i dont have the garage space for a crew longbed. but i could manage. i found a really nice 78 in anchorage while i was up there this last summer. i should have snagged it, but i was having trouble making sense of it, as it too had a bad trans and colorado is a long way from AK

i am excited to see this addition to the truck farm get started!

[COS399]

Looking forward to following this one.

[Vintage Windmills]

Heres the timeline and some background on the purchase:

October 6th, found the truck on craigslist seattle. I could tell it was not a work truck or one that was abused from the pics.






Being remote, I knew I was at a disadvantage so I had to send a message that I was serious and wouldn't BS him. I emailed the following: "Hi, If you have receipts for the motor, clean title and can send a pic of the cab supports showing no rust there I will pay asking price for the truck. Also I am out of state but have had trucks shipped here from oregon before. If you are willing to work with me and can provide the above, consider it sold. I can call you tomorrow."

It worked- he called back and there was good communication from there on out

OCT 7th- told him I was going to line up a friend out there to inspect for rust and verify the title. I was pretty cautious at this point and would not send any money until I had someone look at it first. Now is where it got tricky, as far as the payment went. I wanted to make out a cashiers check to the guy and have a friend bring it with, and then if all looked good, the title would be exchanged for the check. The owner would not agree to this even though the truck would still be sitting there! It even has a bad tranny so it wouldn't be speeding out of there.

OCT 7th-10th detailed discussions on how to get him the money without sending cash and him leaving a bank with cash (without running through his account). Finally agreed that I would open a wells fargo account and send a cashiers check to another wells fargo where he could cash it. Wire transfer options need accounts on both ends FYI.

OCT 9th- detailed pics of concern areas sent. Everything looked good

OCT 14th- I had a well respected member of this forum, Mark (Livrat) check it out for me and verify all VIN's and do a rust and engine condition check. Everything checked out

OCT 16th- had Mark confirm that the place shown on google streetview and Earth was indeed where the truck was he looked at

OCT 20th- title sent to me certified mail

OCT 24th- MN DMV would not transfer title since he only signed the front, which was just a loan release portion.

OCT 25th- Truck was supposed to be picked up today. No word from Shipper for a couple days, he totally blew us off!

OCT 27th- Shipper called said it would be a few days.

NOV 2nd- Shipper called and said he didnt know when he could get it but could get it to his place in MT at least.

NOV 1- Made sure my name was filled in as buyer on the title and sent back to Seattle certified mail with tracking. Made sure to send email to document sending also.

NOV 3rd- I cancelled bid with that shipper

NOV 3rd-6th- Wasted my time with other potential shippers/brokers. Seriously contemplated leaving the truck in Seattle and just picking up myself in the spring.

NOV 6th- Broke down and just called DAS, a little more expensive but at least they are legitimate.

NOV 7- Title received back

NOV 13th- DMV take#2 "newer" lady there struggled a bit with paperwork and all the options for registration but we finally got the right paperwork for a one ton non commercial. The bad news: MN charges 6.5% on one tons and higher! Stupid because my 01 2500HD actually has a higher GVWR than this truck. The good news: Plates say "NONCOMMERCIAL" right on them in good sized writing. I like this since with my 2 place car hauler, I'm going to look commercial and I don't want to be hassled by the DOT.

NOV 14th- DAS shipping website says truck is in transit. No delivery date given though

[Dieselwrencher]

I like how people think a VE can't out tow a BBC. I have a very well used 89 6bt I'd put up against most BBC's. It'll get better mileage towing and can maintain hills without down shifting 2 times too. Been there, had both ford and chevy big blocks, wasn't impressed. And I highly doubt you will see any issues with the extra 400lbs of engine weight during getting the truck going unless you are in a soft field or on snow. The torque these make when you drop a clutch on them is pretty funny. Make sure your idle is set correctly and you'll be fine. The leaf springs will be the only thing I'd see worrying about the weight. And if you have the 4 leaf HD stock springs, they take the weight with no issue.

Jud, this will make a very nice hauler. That is a very nice truck to start with. Hopefully all the snow you guys keep getting doesn't delay the shipment too much. I agree the price of diesel is high. But, what will a 400hp 454 get hauling your trailer with 2 trucks on it? 6, maybe 8 if you are lucky? The worst I've gotten with any 5.9 I've had has been 9.5. That was towing a 36' triple axle enclosed trailer weighing 25,500# and running 75-80mph in 25-30mph winds. The guy running with us had a 8.1 and was lucky to ever get 6. Cost is a huge consideration in any swap and I won't argue that. So overall cost compared to the BBC already in your truck is a no brainer. But over all usage and being happy in the end, I can't see how the 5.9 won't do an over all better job.

[Vintage Windmills]

Originally Posted by COS399

Looking forward to following this one.

Glad you are going to follow, I see you have done the same swap but more complicated so you probably have good tips for sure. 1st question, what did you do for a xmember?

Originally Posted by Dieselwrencher

And if you have the 4 leaf HD stock springs, they take the weight with no issue.

I will have to wait and see. I hope the frame on this truck is beefy enough. I have a feeling looking at pics it is not nearly as strong as my 01 2500hd but that thing has a dump truck frame and is arguable overbuilt. Looking for opinions on that, I would like to just "drop" the engine in and go. I just need to measure it and see what the moment of inertia is I guess and go from there.

Originally Posted by Dieselwrencher

Hopefully all the snow you guys keep getting doesn't delay the shipment too much. Cost is a huge consideration in any swap and I won't argue that. So overall cost compared to the BBC already in your truck is a no brainer. But over all usage and being happy in the end, I can't see how the 5.9 won't do an over all better job.

Good to know you guys are still endorsing the 6bt. I guess the main thing I want is to not fart around with an intercooler, at least for now. That said, can my 90 non I/C engine with pump mods hold 40 mph in the mountains with 14000lbs in tow? THats really all i need. I think the pump was turned up on the 90 6bt since it would pour black smoke if you laid on it. Also it felt about as quick empty as my 6.0 chevy empty, maybe not quite as fast but not a dog either.

Cost is a wash either way, I have the diesel engine, tranny, tcase combo here and can fab anything needed. Truck won't need body work or suspension work hopefully. No I/C, no trans controller, what am I missing, seems like it will be cheap? Maybe a special oil pan or lift to clear the front pumpkin? And some guages. Engine doesn't need anything besides maybe a KDP check/fix and a gasket or two. I will rebuild the g360 and reseal the np205 myself.

[burnin oil]

Originally Posted by Dieselwrencher

I like how people think a VE can't out tow a BBC. I have a very well used 89 6bt I'd put up against most BBC's. It'll get better mileage towing and can maintain hills without down shifting 2 times too. Been there, had both ford and chevy big blocks, wasn't impressed. And I highly doubt you will see any issues with the extra 400lbs of engine weight during getting the truck going unless you are in a soft field or on snow. The torque these make when you drop a clutch on them is pretty funny. Make sure your idle is set correctly and you'll be fine. The leaf springs will be the only thing I'd see worrying about the weight. And if you have the 4 leaf HD stock springs, they take the weight with no issue.

Jud, this will make a very nice hauler. That is a very nice truck to start with. Hopefully all the snow you guys keep getting doesn't delay the shipment too much. I agree the price of diesel is high. But, what will a 400hp 454 get hauling your trailer with 2 trucks on it? 6, maybe 8 if you are lucky? The worst I've gotten with any 5.9 I've had has been 9.5. That was towing a 36' triple axle enclosed trailer weighing 25,500# and running 75-80mph in 25-30mph winds. The guy running with us had a 8.1 and was lucky to ever get 6. Cost is a huge consideration in any swap and I won't argue that. So overall cost compared to the BBC already in your truck is a no brainer. But over all usage and being happy in the end, I can't see how the 5.9 won't do an over all better job.

I love 5.9s and have had a few. My 6.7 gets 7.5-9 MPG loaded with my max at 35k lbs gross. You do have to shift it on a hill. The 5500 does have a 6x4 trans with 4.44 gears. I keep an eye on all these swaps because the 72 will eventually get a 12v 6spd swap.

[Vintage Windmills]

I have no clue where the truck is. You would think DAS could tell you where the vehicle is to the nearest state or two. I mean come on, USPS can tell me where a $10 package is but for over a grand in shipping, they cant tell me where a truck on a 100,000lb semi crawling across the country is?? Sheesh. /rant. Man I am in a bad mood today, hate this weather we are having and my stupid honda blew the coolant hose off this AM and I had to get my silverado out of storage and on these crappy roads. Then the check engine light came on but can't read the code. Tried 4 scanners and none would read it. The connector or wiring in the truck to OBD2 port has an issue I guess. That is irony, can't read the problem code because the code port has a problem Had to wash it again tonight to get winter nastiness off. I know, 1st world problems

[COS399]

[QUOTE=Vintage Windmills;6922228]Glad you are going to follow, I see you have done the same swap but more complicated so you probably have good tips for sure. 1st question, what did you do for a xmember?


I cheated and bought a Cross Member from Auto World in Great Falls, Montana. It was a little spendy but is well built and the owners, Ken and Dawna, are very helpful when it comes to parts and/or questions.

I drove my 88 R30 for about 4 or 5 years without an innercooler. It is a 93 VE but until I moved to Montana and met Ken I didn't know what I needed or how to get one installed.

[Dieselwrencher]

Jud, I'd install the intercooler now. It is a little more work but once you start driving this truck, you won't want to stop, and the intercooler swap won't get done. 2nd gen intercoolers fit this body style very well and are very affordable. You'll want one towing the way you want to.

You also asked if these frames were strong enough I think for towing heavy with the 6bt. I say yes, they are fine. My brother's 88 V30 DRW was together with a 6bt for years and abused more than most trucks and it was fine. The Yellow 89 2500 Burb I did has been on the road for a year and a half or more. Tony tows a tandem axle bumper pull dump trailer and he's said he's had 8-10k in it and his rig is on 35's. He towed enclosed trailers with it to St. Louis and Tn. He's put over 20k on it since the swap. I wouldn't worry about the frame as long as it is structually sound and hasn't had any hackery done to it. By the looks of the body on that truck, it is probably nicer than most of the old trucks in your area.

[Vintage Windmills]

Originally Posted by Dieselwrencher

Jud, I'd install the intercooler now. It is a little more work but once you start driving this truck, you won't want to stop, and the intercooler swap won't get done. 2nd gen intercoolers fit this body style very well and are very affordable. You'll want one towing the way you want to.

I agree after thinking through it some more. A guy is buying a spare 6bt from me tomorrow and he has one from a 96 for 150 dollars. Anything else I should see if he has? I assume all the piping will be custom anyways?

[Dieselwrencher]

Originally Posted by Vintage Windmills

I agree after thinking through it some more. A guy is buying a spare 6bt from me tomorrow and he has one from a 96 for 150 dollars. Anything else I should see if he has? I assume all the piping will be custom anyways?

See if he has the piping as well. Your turbo outlet and engine inlet are 2.5" and the 2nd gens are 3". I'd see if he has the newer vac/ps pump as they are a better design, see if he has a good or core HX35W, and the upper intake off the engine. If he has a fan blade/fan clutch, grab that too.

[Vintage Windmills]

Originally Posted by Dieselwrencher

Jud, it sounds like your engine has the basic fuel screw turned in a bit. Here is what I'd do to make it an awesome hauler and mileage unit. 3200gsk in the injection pump, turn the fuel screw to where you desire and adjust the afc, DennyT Stage II fuel pin, 5x.012 injectors, HX35w from a late 94 up 12v, advance the timing on the IP, and keep an extra lift pump with you or go ahead and upgrade to a low volume piston lift pump. Or even an Airdog or Fass. I have a new cummins one on my truck but these are a diaphram pump and don't live as long as the piston pumps. You will need a little beefier clutch as well to handle the extra power.

Originally Posted by Dieselwrencher

See if he has the piping as well. Your turbo outlet and engine inlet are 2.5" and the 2nd gens are 3". I'd see if he has the newer vac/ps pump as they are a better design, see if he has a good or core HX35W, and the upper intake off the engine. If he has a fan blade/fan clutch, grab that too.

Ryan, All this is tempting but sure is complicating things. Are you saying it won't hold 40mph in the mts or steep hills towing unless I do this? Just going for a simple build here, truck will probably only log 5000 mi a year in reality. Just want enough to do the basics, and keep total additional expenses under $2k. I think I'll invest in a new or better clutch setup as this one was a tad "hoppy" starting out.

[Vintage Windmills]

Good to hear on the frame, am curious to see it when truck gets here.


Did you guys have any thoughts on the mods done to my 6bt based on what iI said above??

[Dieselwrencher]

Jud, it sounds like your engine has the basic fuel screw turned in a bit. Here is what I'd do to make it an awesome hauler and mileage unit. 3200gsk in the injection pump, turn the fuel screw to where you desire and adjust the afc, DennyT Stage II fuel pin, 5x.012 injectors, HX35w from a late 94 up 12v, advance the timing on the IP, and keep an extra lift pump with you or go ahead and upgrade to a low volume piston lift pump. Or even an Airdog or Fass. I have a new cummins one on my truck but these are a diaphram pump and don't live as long as the piston pumps. You will need a little beefier clutch as well to handle the extra power.