K30 Downgrade to Cummins Project

[Vintage Windmills]

Originally Posted by Dieselwrencher

From what I can see on your engine position, you are still way too far forward. I can also tell you, for a tow rig you want a mechanical fan. You will want to jump up to the dodge radiator too and ditch the stock BBC radiator. My truck has a stock BBC radiator and it does just fine towing 15k on an open trailer.

I realize you're trying to get by with not much lift but I don't think you will get there without putting the engine a little farther down and back more. If you want I can send you a dodge exhaust manifold so your mount issues are a little easier. I probably have a dodge oil drain too. The ford bus/F700 AC mount is probably the one you're talking about. They're pretty pricey. Auto world also makes mounting brackets and a dual pulley to put ac compressors on the head above the injection pump.

Thanks for the info. Most of the time I'll be towing 8000lbs on an open trailer and the most would be 15k on an open. Don't own an enclosed, at least yet That said, I don't want to have an issue if i get in traffic on a hot day. How many core is the 94 dodge stock rad? I could get an upgraded BBC 4 core. Currently there is a 3 core in there. I've got a 2nd gen intercooler for this, looks like it will fit well but I may have to cut the core support upright braces to not push the stock 86 grille out the nose too far.

Actually i'm within an inch (front to back) of where most of the mount kits for these trucks have the engine placed. If i move the engine down any more I'll definitely need to lift it since the axle will be too close to the oil pan. Is the fan the only reason you're saying go down and back? I can't go back without going down.

As for the dodge manifold, thank for the offer. I need to do more homework though since I feel that will create an issue of putting the turbo too close to AC/heater box if i go with stock chevy AC box for the evaporator? I need to see if thats a better option vs the Thermo King or Vintage air. uugggh many considerations.

[Dieselwrencher]

Jud, if you're going to use a 2nd gen intercooler, just get a dodge cummins radiator. Mine currently is a 4 core so I don't think you going from the 3 core to 4 core will be enough. Yes, it will work, but there will be a time it won't be enough. I'm going to put a dodge one in my truck before summer. Watching your temp gauge at 232* and climbing is not fun.

Yes, I'm saying to get that engine as far back as you can because you will need it for the clearance on the clutch fan to the radiator. Here again you can get by with electric fans. I have done a couple of trucks with electric fans. They work alright until they don't. Then good luck getting parts at a normal parts store.

The dodge manifold might put it close to a stock hvac box. I did have one in my 76 on a 24v and it fit. So there again, it's all about where the engine is placed. You can also flip the dodge manifold and put the turbo above the hvac box. That's how I have it on my 72 and my Excursion.

[Vintage Windmills]

So its proving to be a bit harder to find a dodge rad I like than I thought.

I'm compiling notes here:
Rock auto sells a bunch of stock replacement options but all are 2 core (2.2 core thick) with plastic tanks for $150 or less. Are you saying this stock class will work for tow rig status with my engine power level?

Champion makes a 3 core (2.25 core thick) for $250 but its only listed as applicable for the gas truck engines. Good news is its all alum and rated for 850 HP. I know those HP ratings only apply for a certain duty cycle though (read drag racing or street use and not prolonged towing up long hills )

Champion makes a 4 core BBC (2.8 core thick) for $275 listed for 1000+ HP.

Then there are the 2 core (2.7 core thick) for $800 made by Griffin.

Key learning, its also about core thickness and not just the number of cores.

The positives of running the BBC radiator
- may not have to cut the core support all to bits (only if intercooler needs to come closer to rad).
- stock fit
- as high a HP rating as the thinner, wider Cummins ones.

The negatives of running the BBC radiator
- not as proven in a towing capacity as a cummins one
- ports are 1.5 instead of 1.75/2.00 on a cummins one
- thicker core means less clearance to front of engine
- not cutting core support means I have the thickness of the core support "beams" wasting space between rad and intercooler and making it hard or impossible to fit the grille on the front of the truck. Especially with AC condenser up there. Maybe I can put the condenser after the intercooler....

[Dieselwrencher]

Jud, I did put a Champion radiator like the one you have pictured in that yellow suburban I did. It worked, but I'm not sure how it would do with a big enclosed trailer or large 5th wheel. I know the owner towed a 16' enclosed from tennessee to Iowa 2 different times and said it did fine. But I can't imagine the weight was as great as a large enclosed filled would be.

I've used a lot of these and had good results. I've had very little luck getting radiators shipped to me so I prefer to walk in and buy one. If it's damaged, they walk back and get another.

https://www.napaonline.com/en/p/NRS2464

Here's a really good one but it is pricey. I've put in a few of these and they are pretty nice. I can get you a price on one if you decide to go that route.

https://www.thoroughbreddiesel.com/mmrad-ram-94/

I put a 2nd gen intercooler on my brother's 84 K20 and it fit great. Had room to use the stock hood latch etc. Had plenty of room to put the grill on too.

[Vintage Windmills]

Thanks Ryan, good point on being able to return it. Do you know how thick the core is or how many rows it has? I can't find much info on the Napa site.

Have you seen these? They look nice, are 4 core (2.44 in thick) and all aluminum. https://www.ebay.com/itm/253878616552?ul_noapp=true

losing my cool over these radiators

[Dieselwrencher]

The stock dodge cummins ones are 3 core. That ebay one looks pretty nice for the money. As long as they are good on their warranty, you should be good to go.

[DieselSJ]

Don't get focused on 4 row. 2 fat rows will outcool 4 thin rows.

[Vintage Windmills]

I decided to roll the dice and try the all aluminum 2.44 thick 4 core off ebay. Its being shipped and now I'm working on figuring out the trans crossmember. Think I'll just build it from scratch or modify the chevy one.

on this cold day I'm putting a list together of things I need to research and figure out.

- Tach- Whats the best way to get a tach on this thing?
- AC compressor mount- needs to be up higher. I could try to locate a medium duty truck water outlet/mount bracket but it may be $400? Otherwise I could maybe buy this
setup but I'm concerned they say the lower water neck needs to point down at 45 degrees. I don't want to do that since that will send it right towards the frame rail.
https://www.dieselconversion.com/hig...l#!prettyPhoto

-Cruise control - whats a good non vacuum option?
-Dmax rear axle springs are so long, I'd have to move the stock saddle fuel tanks. The springs in the truck are 10 leaf and look like they'll be pretty stiff. Perhaps if/when I swap
to the AAM 11.5 I will just get a set of stock K20 rear springs. I have the air lift airbags in the rear for capacity when hauling heavy.
-Fuel system - need to figure out if I should replace/upgrade the tanks or just flush them out. I'd like to run the dual tank setup. Trying to remember if the lift pump on the
engine is enough to draw the fuel or if i need a pump closer to the tank. Can't remember what the dodge gen 1's did. I think they just used the lift pump.

[Dieselwrencher]

Originally Posted by Vintage Windmills

I decided to roll the dice and try the all aluminum 2.44 thick 4 core off ebay. Its being shipped and now I'm working on figuring out the trans crossmember. Think I'll just build it from scratch or modify the chevy one.

on this cold day I'm putting a list together of things I need to research and figure out.

- Tach- Whats the best way to get a tach on this thing?
- AC compressor mount- needs to be up higher. I could try to locate a medium duty truck water outlet/mount bracket but it may be $400? Otherwise I could maybe buy this
setup but I'm concerned they say the lower water neck needs to point down at 45 degrees. I don't want to do that since that will send it right towards the frame rail.
https://www.dieselconversion.com/hig...l#!prettyPhoto

-Cruise control - whats a good non vacuum option?
-Dmax rear axle springs are so long, I'd have to move the stock saddle fuel tanks. The springs in the truck are 10 leaf and look like they'll be pretty stiff. Perhaps if/when I swap
to the AAM 11.5 I will just get a set of stock K20 rear springs. I have the air lift airbags in the rear for capacity when hauling heavy.
-Fuel system - need to figure out if I should replace/upgrade the tanks or just flush them out. I'd like to run the dual tank setup. Trying to remember if the lift pump on the
engine is enough to draw the fuel or if i need a pump closer to the tank. Can't remember what the dodge gen 1's did. I think they just used the lift pump.

Does your truck have a factory tach currently? On my 72 I haven't gotten my tach done but I am using a dodge pick up sensor from a 92-early 98. I'm also using that style balancer that has 2 extra grooves cut into it so it will pick up the proper pulse for the gm tach. You can then wire the pick up sensor to your truck harness but you have to add a 1k ohm resistor to the pick up sensor harness so the tach will work correctly.

Or you can get a signal conversion box from dakota digital or even off ebay.

AC compressor mount...... Here is a link to a thread that has the part numbers listed in it if you need them. If you go this route and let me know and I'll get you some prices if you'd like.

https://www.ford-trucks.com/forums/1...bracket-2.html

That DCS one does allow you to use your stock dodge alternator and the price isn't horrible. On the lower inlet you could make your own. Make a flat flange that bolts to the new mount and then use 90s and cut/weld to get your angle you need. On my Corvette I cut up a dodge bracket and welded a 90* bend on it and it's been on there since.

I feel this is one of the best cruise control set ups out there. Years ago I put some on semis and they worked great.

http://www.rostra.com/universal-afte...-by-rostra.php

As far as the fuel system goes, you can run your stock stuff and use that stock switch over valve. You don't need another pump other than the lift pump that is on the side of the engine block. The only thing that I don't like about using the dual tank set up is it is kind of small line size if you are running a p pump at volume. At the power levels you're going to be you would be fine though.

As far as the newer leaf spring swaps etc, I'm no help there. I haven't done any on these trucks.

[Vintage Windmills]

Originally Posted by Dieselwrencher

Does your truck have a factory tach currently? On my 72 I haven't gotten my tach done but I am using a dodge pick up sensor from a 92-early 98. I'm also using that style balancer that has 2 extra grooves cut into it so it will pick up the proper pulse for the gm tach. You can then wire the pick up sensor to your truck harness but you have to add a 1k ohm resistor to the pick up sensor harness so the tach will work correctly.

Or you can get a signal conversion box from dakota digital or even off ebay.

Thanks Ryan. Not a factory tach truck. There's a Sunpro tach that was installed for the BBC. It reads pretty high for a diesel. I'm mainly trying to figure out the pick up sensor. It seems I may be able to tap into the alternator rectifier, add a different damper with more grooves, or just add a 4pulse ring like this: http://www.destroked.com/mobile/prod_tach_kits.php Where did you mount your pick up sensor?

Originally Posted by Dieselwrencher

AC compressor mount...... Here is a link to a thread that has the part numbers listed in it if you need them. If you go this route and let me know and I'll get you some prices if you'd like.

https://www.ford-trucks.com/forums/1...bracket-2.html

That DCS one does allow you to use your stock dodge alternator and the price isn't horrible. On the lower inlet you could make your own. Make a flat flange that bolts to the new mount and then use 90s and cut/weld to get your angle you need. On my Corvette I cut up a dodge bracket and welded a 90* bend on it and it's been on there since.

Good reference on the part numbers, I need to compare the options today while looking at where the boost and air intake tubes will run.

[Vintage Windmills]

Pics of the rad. Looks good and box was in good shape and it was well packed. The funny thing is the one mount ear was bent. It must have been bent before being boxed LOL. Shouldn't be a big deal though. The size and quality looks good to me.


I bought a fan off craigs to see if I could fit the mech fan and I can get about 3/4" clearance it seems but I need to mock up grille, intercooler and AC conderser to confirm. The thing I'm not liking is the fan is too low it seems. The tips dip below the core support about 3 or 4 inches.

[Vintage Windmills]

Also I wasn't able to work in the shop much this past week. We were below zero for 3 days straight. Cut some dry oak to keep the house warm while I worked from home. Our office was pretty much closed and people were encouraged to work remotely. Brrr.

[Vintage Windmills]

This post is for my notes on the AC stuff:

Moving compressor up puts the back within 1" of the oil filter on the engine THis compressor is a about 8.5" overall length, which appears to be about the same as one on Vintage air site, the Sanden SD508. Vintage air also shows a SD-7B10 that is 7" overall length. I need to call them and see what compressor comes in the kit for a non AC squarebody. Here are the compressor dims: https://www.vintageair.com/universit...0-compressors/

Perhaps I could run a gmt400 type of AC compressor. They are pretty low profile but brackets would be more hassle. Here is one on rock auto: https://www.rockauto.com/en/moreinfo...051007&jsn=620

Need to do more thinking on the VA kit, it appears that adding the dash vents can be a pain and I'd lose glovebox space. Here is thread for reference http://67-72chevytrucks.com/vboard/s...d.php?t=489024

Trying to weigh the options of VA vs a factory swap.

I could sure use a squarebody parts truck for AC parts, a clutch pedal setup, and ideally an aux battery tray, power windows and locks, cruise, floor shift tilt column, tow hooks. You would think there'd be some rusty affordable ones around here but I haven't been able to find anything with more than a couple things on the wish list above for a good price.

[v30crewcab]

Ive had a 454 rad in mine for many years. never had it overheat. I have pulled 26K and not had any issues. my gooseneck and crane are close to 20K by themselves.

[Vintage Windmills]

Originally Posted by v30crewcab

Ive had a 454 rad in mine for many years. never had it overheat. I have pulled 26K and not had any issues. my gooseneck and crane are close to 20K by themselves.

Nice, glad to hear. Are you using mechanical dodge fan?

[Vintage Windmills]

Some parts that arrived:
-clutch rated for 450hp, should be 25 or 50 more than i need.
-new flywheel
-np205 rebuild kit, not sure if needed now or if I will save for the future but the price wasn't bad and I won't know until I pop some covers off. The np205 worked fine when I drove the dodge it was in.

Also I made an adapter plate for lifing np205's that bolts to my floor jack

[Vintage Windmills]

Seems like there's no traffic in this area of the forum anymore.... no posts in any threads in the diesel conversions section today. Overall traffic on the entire website seems to be a fraction of what it was a few years ago. Where did everyone go? Are people reading this thread besides those that post? Is there a better area for these projects?

[COS399]

Just my opinion but I think everybody might have shifted over to a quicker platform. This is kind of like writing a letter and almost everyone wants it now and they don't want to wait. Keep posting and I will keep reading along.

That issue with all the lost photos didn't help either.

[Dewey72]

Originally Posted by Vintage Windmills

Seems like there's no traffic in this area of the forum anymore.... no posts in any threads in the diesel conversions section today. Overall traffic on the entire website seems to be a fraction of what it was a few years ago. Where did everyone go? Are people reading this thread besides those that post? Is there a better area for these projects?

Ya I follow along and check in at least once a day but just realized I haven't posted on my thread in almost a year!! My bad. I'll try to get a update this weekend.

[Vintage Windmills]

Originally Posted by Dieselwrencher

Have you looked at the industrial 5,9 tensioners to see if they'll work for you? I've had very little luck with the 3rd gen after market ones living short lives. Would an intercooled 1st gen fan hub suite your needs better? They are raised up a little more than the 2nd gen ones. You could make your own mount with DOM, flat plate and gussets. Tony made one for his suburban but I'm not sure he posts on here much anymore. I'll message him and have him put his pics here. I sent you an email with a pic of some hooks too.

I found a new 3rd gen Cummins genuine tensioner for $75 so went with that.

An IC 1st gen hub would probably work better but they are hard to find. Do you have one? I wish I had one to at least borrow to look at/measure. Unfortunately I sold both 92 dodge w250's i had awhile back. I may just fab one up like you say.

Got your email. now I see you emailed me back late Jan, not sure why i didn't get it or see it before!

Originally Posted by Dewey72

Ya I follow along and check in at least once a day but just realized I haven't posted on my thread in almost a year!! My bad. I'll try to get a update this weekend.

Sounds good! You have a great project there and we'd like to see more of it.


I took the running boards off awhile back but forgot to post a pic. I think it looks better

[randy500]

I started reading your build a couple weeks ago, I like it.

Looks like your working out the ac compressor mount. I bought the Cummins high mount freighliner parts and modified the alternator bracket so I could use the dodge denso unit. When I was doing the changeover I felt like I could have modified the low mount ac bracket like you are working on.
Looks like you will have to change water necks for belt clearance.
When I put the ac on mine I tried the tensioner up high like you have yours sitting (4bt style) I hade very little belt clearance and the belt length had to be spot on, took a bunch of fitting and belt searches and in the end the tensioner did not tension the ac compressor enough which caused it to chip from belt skipping and when that happens The tensioner has wild adjustment fluctuations. It was jumping crazy back and forth trying to keep tension.

I read it’s best to have the tensioner last in-line and that’s what I did, I put it down by the frame rail, fixed the problem.

For belt length I cut my old dodge belt then used it to wrap and mark needed belt length, laid it out flat and measured the length then found that length online in the gates or dayco online catalog. Belts are $50 or so local but I found the ones I needed on rockauto, amazon and eBay for about $20 or less.
There are plenty of 8rib belts in the length you need...that had me worried too.

For your tach, you can get a tach signal from the 2nd gen crank sensor, I wrote up how to do it, just set your aftermarket gas tach to 4 cyl mode and it will read correctly (2 pulse per revolution) which you get from the 2nd gen sensor.

You have probably already looked it up but a 1st gen fan hub will move the fan up and center I believe, it also gives you .75” or so of more fan to radiator clearance, the pulley is different from 2ng gen so you need it with the fan hub.

[randy500]

I will share some A/C things I learned too...
The sanden sd715 compressors, I think all have the same bolt pattern and the variances are compressor clutch style and clutch groove centerline and back head style.
The wires vary and have or do not have diodes, change out as needed.

I bought a new compressor from acparts.com for about $130, it was a random compressor that had the proper 8rib centerline and a head configuration I thought would work and it did. I searched by price then researched attributes of compressor number on the sanden website.

As far as your home made bracket...if you can somehow duplicate the lower compressor bolt centerline to above the waterneck it will all line up when installed. I think you could fasten the existing bracket to a bench, find or attach a measuring point and modify away.
Maybe you Could make a flat plate for the ac compressor that mounts to the lower bolt holes with spacers and hole that clears the waterneck? If so you could lay out the pattern on flat plate then bolt it to the dodge cast iron bracket.
You can ballpark the lower alternator mount and adjust with shims or spacers to get the centerline right.

I made my own lines using aeroquip ez-clip fittings and line, these lines and fittings are expensive in kit form or new but can be found on ebay super cheap. They “crimp” using cv joint clamp type pliers, aeroquip sells the crimpers for $120 or so.
I used Oetiker side jaw pincer pliers for single ear clamps. I used the single ear clamps on my fuel, vacuum and pressure lines too, eliminating gear driven hose clamps which I hate.
Compatable fittings to aeroquip are available under weatherhead and red dot brand names too (eBay and other sites), they are all identical.
There are a limited number of ac line sizes and fitting types, fitting charts are online, just match up to the parts you have like condenser, evaporator and compressor head or manifold,
Nice looking lines, very heavy duty and easy to assemble and crimp at home.

I have some pictures of the ac stuff in my crew cab preview thread.

[Dieselwrencher]

Originally Posted by Vintage Windmills

I found a new 3rd gen Cummins genuine tensioner for $75 so went with that.

An IC 1st gen hub would probably work better but they are hard to find. Do you have one? I wish I had one to at least borrow to look at/measure. Unfortunately I sold both 92 dodge w250's i had awhile back. I may just fab one up like you say.

Jud, the only one I have is on my Longhorn. I'll dig through my stash and see what else I have. I used to have a couple weird ones off of 4BT's.

[Vintage Windmills]

Originally Posted by randy500

I started reading your build a couple weeks ago, I like it.

Looks like you will have to change water necks for belt clearance.
When I put the ac on mine I tried the tensioner up high like you have yours sitting (4bt style) I hade very little belt clearance and the belt length had to be spot on, took a bunch of fitting and belt searches and in the end the tensioner did not tension the ac compressor enough which caused it to chip from belt skipping and when that happens The tensioner has wild adjustment fluctuations. It was jumping crazy back and forth trying to keep tension.

I read it’s best to have the tensioner last in-line and that’s what I did, I put it down by the frame rail, fixed the problem.

You have probably already looked it up but a 1st gen fan hub will move the fan up and center I believe, it also gives you .75” or so of more fan to radiator clearance, the pulley is different from 2ng gen so you need it with the fan hub.

Thanks Randy for the good info. You;re right about the tensioner placement. I have redesigned it to have an idler pulley rigidly mounted by the water neck and the tensioner down by the frame rail. Below is kind of a mockup showing where things will be. I think there will still be enough wrap angle on the crank pulley, that is my only concern at this point.

Also shown is a pic of my machined DOM and steel plate solution that will do the same thing as the 1st gen intercooled fan hub mount.

Originally Posted by randy500

As far as your home made bracket...if you can somehow duplicate the lower compressor bolt centerline to above the waterneck it will all line up when installed. I think you could fasten the existing bracket to a bench, find or attach a measuring point and modify away.
Maybe you Could make a flat plate for the ac compressor that mounts to the lower bolt holes with spacers and hole that clears the waterneck?
You can ballpark the lower alternator mount and adjust with shims or spacers to get the centerline right.

Yep, I put a straightedge from another pulley on the engine and measured off that to set the distance for offset. My bracket ties to the engine in two spots and the bolt hole on the lower waterneck that the tensioner used to go into. I think I can do an angle iron bracket off the old compressor block mount holes for the belt tensioner.

Originally Posted by Dieselwrencher

Jud, the only one I have is on my Longhorn. I'll dig through my stash and see what else I have. I used to have a couple weird ones off of 4BT's.

No worries, I want with the DOM and plate fabrication. The fan is now about 2 inches higher and 1.25" towards passenger side compared to than the 2nd gen position. Its weird the passenger side shift works better with the 2nd gen fan shroud, rad and radiator hose setup. I don't know if my hoses are longer and need to be cut to length or what, but I expected the left right with all 2nd gen stuff to work best with the 2nd gen fan position!

[Dieselwrencher]

Jud, which tow hooks are you looking for? Just the standard ones that came on these 80s square bodys?

I know a lot of the guys that used to post in here just got too busy and don't get on here much, or they moved on to other social media sites. But I feel this is still a better place to get and find info. Especially for your own builds.