‘91 FWC K5

[ZooMad75]

Having run 3.73’s, 35’s and a 465 in my old rig with a wheezy carb’d 350 it went nowhere fast. Even less fast when climbing hills around me. A 4bt would have more torque for sure but it’s doesn’t feel like a good combo. Besides having to deal with that paint shaker of an engine.

I might suggest to toss a carb on the 350 and rule out the injection system if it’s the problem. I know that’s a bit a work in its own right but it’s quicker than swapping in a 4bt/465.

 

[joshuak]

Hoping to fix that with the 3.73s and 35s

Info from the grimmjeeper gear calculator doesn’t look favorable on that combo…

I understand you want to keep the rpm of the 4bt bellow 2k to keep fuel efficiency and this is what it would look like with a 465/208 combo and 3.73 at the axles.



Not saying don’t, just saying beware.

I have Isuzu’s version of the 4bt in a square and it puts a huge smile on my face to drive it.

Good luck with whatever you choose.

 

[TooManyProjects]

Thats the 4db1 right? What trans are you running? Im not against a 4500, just the shifter sorta lands in the wrong spot I think. When I put the 3500 in my other k5 the shifter hole sorta ran into the transfer case shifter, that was the motivation for the 465, the holes marked. Also thought about a gear vendors with but a 4500 is the same deal pretty much but cheaper.

Info from the grimmjeeper gear calculator doesn’t look favorable on that combo…

I understand you want to keep the rpm of the 4bt bellow 2k to keep fuel efficiency and this is what it would look like with a 465/208 combo and 3.73 at the axles.

View attachment 478336

Not saying don’t, just saying beware.

I have Isuzu’s version of the 4bt in a square and it puts a huge smile on my face to drive it.

Good luck with whatever you choose.

 

[TooManyProjects]

Having run 3.73’s, 35’s and a 465 in my old rig with a wheezy carb’d 350 it went nowhere fast. Even less fast when climbing hills around me. A 4bt would have more torque for sure but it’s doesn’t feel like a good combo. Besides having to deal with that paint shaker of an engine.

I might suggest to toss a carb on the 350 and rule out the injection system if it’s the problem. I know that’s a bit a work in its own right but it’s quicker than swapping in a 4bt/465.

Ive heavily thought about tossing an avs2 offroad carb on it, just trying to figure out the trans setup too, if I get too much wrapped up in the 350 then maybe ill want to go a different direction on the trans, not sure, the 700 occasionally slips 2nd and 3rd. Not sure why, its been rebuilt and currently it makes no power so wondering what the trans health is looking like

 

[joshuak]

Thats the 4db1 right? What trans are you running? Im not against a 4500, just the shifter sorta lands in the wrong spot I think. When I put the 3500 in my other k5 the shifter hole sorta ran into the transfer case shifter, that was the motivation for the 465, the holes marked. Also thought about a gear vendors with but a 4500 is the same deal pretty much but cheaper.

Yep, mine’s a 4bd1t, although the indirect injected 4bd2t are out there too.

I have the nv4500, yes a little off from the OEM hole. But I would imagine that if I had worked harder on engine placement I could have gotten the shifter closer. Honestly it wasn’t a consideration at the time.

Mock up.



Finished product.



Because picture whore, DP came to visit and helped.

 

[TooManyProjects]

Yep, mine’s a 4bd1t, although the indirect injected 4bd2t are out there too.

I have the nv4500, yes a little off from the OEM hole. But I would imagine that if I had worked harder on engine placement I could have gotten the shifter closer. Honestly it wasn’t a consideration at the time.

Mock up.

View attachment 478342

Finished product.

View attachment 478343

Because picture whore, DP came to visit and helped.

View attachment 478344

That 3.9 looks like it was supposed to be there, hows the intercooler setup?

Hows the vibration with the 4cyl? Im not looking for a modern feel with smooth running but for something I plan to drive alot id like to avoid an eye floating vibration. I assume its noticeable but not bad.

By the looks of it im pretty better off with an early 4500 with the 6.5:1 low first and OD, maybe I can use the 3.9 length to my advantage and push it forward a couple inches to better fit the shifter or use a cable shifter for the t case and move it back or something. My 3500/241 combo worked fine so its not a huge deal, but made shift boots difficult.

 

[Cucv_M1008]

2jz swap

 

[joshuak]

That 3.9 looks like it was supposed to be there, hows the intercooler setup?

Plenty of room.

In hindsight bigger is better, should have installed the biggest I could fit. Instead I sized it according to engine requirements and advertised cfm. OEM rad and shroud.

For pics again DP to the rescue.

Hows the vibration with the 4cyl?

Compared to a 6.2 diesel, I don’t notice much if any difference. When turning off the engine more perhaps.

Im not looking for a modern feel with smooth running but for something I plan to drive alot id like to avoid an eye floating vibration. I assume its noticeable but not bad.

Proper motor mounts have a lot to do with it I think too. Check out Alan2smiley’s (?) build, he did a really nice job.

By the looks of it im pretty better off with an early 4500 with the 6.5:1 low first and OD,

Fair warning, I’ll shift three times to get through and intersection if there is any sort of upwards slope.

maybe I can use the 3.9 length to my advantage and push it forward a couple inches to better fit the shifter or use a cable shifter for the t case and move it back or something.

Lots of room.

My 3500/241 combo worked fine so its not a huge deal, but made shift boots difficult.

Understood, low on my “to do” list is clean up that area.


If I could suggest something is try and ride/drive one before you commit. If you find yourself in DE/MD area stop by.

 

[TooManyProjects]

Plenty of room.

In hindsight bigger is better, should have installed the biggest I could fit. Instead I sized it according to engine requirements and advertised cfm. OEM rad and shroud.

For pics again DP to the rescue.

View attachment 478356





Compared to a 6.2 diesel, I don’t notice much if any difference. When turning off the engine more perhaps.



Proper motor mounts have a lot to do with it I think too. Check out Alan2smiley’s (?) build, he did a really nice job.



Fair warning, I’ll shift three times to get through and intersection if there is any sort of upwards slope.



Lots of room.



Understood, low on my “to do” list is clean up that area.


If I could suggest something is try and ride/drive one before you commit. If you find yourself in DE/MD area stop by.

Well, I appreciate all the info, I’ve driven several 6.2s and 6.5s, the vibration was so little in my mind that its not a concern, so thats good, ive never driven a 4b or 6b so I wasnt sure what to expect.

In regards to driving one first, im looking at a bread truck thats a 92 oshkosh 4bta 4 speed so I could get a feel for it if I ended up with that one. Trying to figure out if the oshkosh rigs used the gm adapter or not, id like to run a gm trans and the adapters are rather expensive aftermarket.

 

[Chickntrk]

Well, I appreciate all the info, I’ve driven several 6.2s and 6.5s, the vibration was so little in my mind that its not a concern, so thats good, ive never driven a 4b or 6b so I wasnt sure what to expect.

In regards to driving one first, im looking at a bread truck thats a 92 oshkosh 4bta 4 speed so I could get a feel for it if I ended up with that one. Trying to figure out if the oshkosh rigs used the gm adapter or not, id like to run a gm trans and the adapters are rather expensive aftermarket.

The 4bt is nowhere near a 6.2 or 6.5 in the shake, rattle roll dept. definitely drive one first…..it’s a great engine and they live pretty much forever but I’d never want one in something I planned to drive somewhat regularly…..even a 6bt is smooth in comparison. Like Rob said, paint shaker is an accurate description.

 

[joshuak]

...

In regards to driving one first, im looking at a bread truck thats a 92 oshkosh 4bta 4 speed so I could get a feel for it if I ended up with that one. Trying to figure out if the oshkosh rigs used the gm adapter or not, id like to run a gm trans and the adapters are rather expensive aftermarket.

Don't know if this is the case with the Oshkosh rigs, but I believe that the bread trucks that had a 4bt/gm tranny had an adapter that tilted the engine 15 degrees or so. So buyer beware!

And like most things, I would multiply what you think the swap will cost by 1.5 or 2 for a little bit more accurate number. Nickle and dime you to death.

 

[ZooMad75]

The 4bt is nowhere near a 6.2 or 6.5 in the shake, rattle roll dept. definitely drive one first…..it’s a great engine and they live pretty much forever but I’d never want one in something I planned to drive somewhat regularly…..even a 6bt is smooth in comparison. Like Rob said, paint shaker is an accurate description.

We were still selling the 4bt option at workhorse on the step vans when I was there. It was lightly used compared to the na 6.5.

One in particular I got sent out to inspect was a step van in MO that was used for a florist. They ordered it with ac and the 4bt. Problem was the Cummins shook so much the brackets for the compressor kept having the bolts rattle out of the block and head. If that gives you any idea of what they do I don’t know what else to say. Part of the issue was the design of the bracket, but the other was the constant vibration. Engineering had to completely revamp the design to fix the issue as the shaking wasn’t going to be stopped.

I’m not anybody to tell a guy what he can or can’t do on his rig, but I agree with the suggestion to go drive anything with that engine and see for yourself what it does and make your own call on it.

 

[TooManyProjects]

Don't know if this is the case with the Oshkosh rigs, but I believe that the bread trucks that had a 4bt/gm tranny had an adapter that tilted the engine 15 degrees or so. So buyer beware!

And like most things, I would multiply what you think the swap will cost by 1.5 or 2 for a little bit more accurate number. Nickle and dime you to death.

Any inherent issues with the motor being tilted?

 

[Truckman4life]

Ford inline diesels in their older f650/750 trucks were tilted a lot. If designed that way then keep it that way.

 

[joshuak]

Any inherent issues with the motor being tilted?

Not that I know of. They had their reasons in doing it that way.

To me having to deal with that would add an extra level of complexity when trying to set the driveline angle, that I would be willing to avoid by paying for one of the more common adapters. Even things like motor mount brackets, you can pay for someone’s R&D or try your hand at it.

Trying to say I did my swap in the driveway, on dirt. Was frustrating at times. Having parts that were made to fit and work together would have been nice.

 

[TooManyProjects]

Well im finally getting around to doing something with it, it sat for a couple months and in the meantime it lost fuel and spark, will be dragging it into the shop and ordering an avs2 offroad carb and all the goodies for that, not quite ready to give up on the 350 after watching VGGs new video with the blue square, ive never had a 350 problem, only efi problems, so time to loose the efi part and go from there, hopefully mr slippy holds together for a while if I get it back on the road.

In the meantime ill slowly look for parts for plan C, I want to find a diy4x dash, and Id like to have a hydroboost hydraulic clutch pedal assembly on standby for whatever diesel 4/5 speed combination I decide to go with long term.

With any luck Ill get the truck to a good useable/ driveable state and get working on the FWC later this year

 

[TooManyProjects]

Quick update, carbs on, it runs with fuel in the bowl, diesel sending unit should be in tomorrow to get the tank back in, carter pump, 2 micron filter and regulator are mounted, will finish AN lines tomorrow too.

If anyone is local and wants a decent used set of tbi hard lines tank to throttle body ive got a set.

Also noticed the rear frames bent on the bottom flange, looks like it was rear ended with a drop hitch in or something and the receiver smoked the bottom flange, or someone had way too much tounge weight and broke the rear receiver bolts, not sure. Also looks like it may have bowed the frame at one point above the axle, frame looks alright now I think so maybe it was straightened but the cab floor in the back still has the bow in it. Not really affecting anything so who cares lol.

 

[TooManyProjects]

Swap is done, been driving it a couple days now. Out of the box untouched the carb runs better than the Tbi was before it gave up on me. Half of the tbi harness had bare spots from it rubbing the firewall. Could have been fixed but by the time we found that I was committed.
Ive adjusted the choke a couple notches and turned the high idle down. Even at 28 degrees when I got off work it fired right up and drove, didn’t even have to warm it up any. Its already good and will get better as I learn how to tune it(my first carb truck). Now my biggest problem is I think the trans is slipping the 2-3 shift. Piece by piece it will get somewhere, but for now I can actually enjoy driving it again.

 

[TooManyProjects]

Little update, looks like im picking up a hydraulic 465 this weekend, starting the parts collection for removing the fluid heater between the 350 and 241. Going to need a set of vac brake hydro pedals if anyone has any floating around. Also going to have to find a 32 spline 208/241/243 to rob the input gear and bearing out of. Probably going to do a SYE while im in there and add a parking brake to the t case or something along those lines. Really looking forward to ironing out the driveline on this unit and hopefully starting the FWC restoration part of this project. Taking a week out in Montana in June to visit my buddy, would sure be nice to have the camper done…. Tacoma trip this go around.

 

[ZooMad75]

Look in the classified section here or post a wanted ad for it in that forum. Usually somebody has a set. I’m all for switching to the manual, and I know you are going to pick up a 465, I would keep an eye out for a 4500. If you do plan on road tripping a lot the OD is nice to keep your sanity rather than listening to the 350 buzz along at 3000 rpm or up depending on your hearing and tire size.