4bt swap questions

[oskarkat]

I'm interested in a 4bt swap with an automatic transmission like the TH400.
How much mod is required? I'd like to keep the stock body height i.e no springover. I tried searching the posts about this but it was very confusing. Can I keep the stock axles and transfer case? I'm not worried about driving 70 mph for hours in it because I'll never do it. 50 mph for 50 miles would be about it. The stock engine is gone, replaced with a 350. It runs pretty good but burns some oil and was obviously just yanked from some donor car without any rebuild. I'd like to start finding the parts so I don't have to pay the "I need it now" premium.

Any advice would be great!

[poolmike]

Shouldn't be a problem running spring under, may come custom oil pan work, nothing serious. Adapters are available to just about every trans. Definitely worth it.

[tndonor]

For what is worth, I had a 4b in my 1980 J10. Not the same but close enough for some generalities.

1. There are many variations of the 4b out there. You will need a motor from a road use application (VE pump or P7100....much more rare and $$$). There are lucas pump which operate from load induced..... WILL NOT WORK. Even a 4b from a genset may have a VE pump but will have a camshaft designed to operate at say 1200 rpms constantly.

2. There are adapters for chevy auto, manual, and for ford manual (these are the common adapters) with chevy manual probably the most common. There are also SAE adapters for say allisons, spicers etc.

3.You should be OK with the oil pan. It will help if not be necessary to have a rear sump oil pan with pickup. Im not 100 percent on this but Im bringing home my first 715 here SOON and can look at it further

I have a guy here in Knoxville that does all my diesel conversion fabbing and ordering. If you need something, Id be happy to pass you the contact info. Always good to atleast have more than one set of prices when gathering parts. All he does is Cummins conversions and he is an authorized Cummins dealer.

Also check out www.4btswaps.com
I had a 1980 Jeep J10 you can search for you get bored.
Keep us posted and Ill help however I can

Ill be putting a Cummins in my 715....... just not a 4B

[oskarkat]

Thanks for the quick replies! I'm relieved to hear that it will fit without the springover. I plan to use the truck as a semi-daily driver, pick up stuff for the shop....the bed is high enough already. I move alot of heavy stuff by myself and I'd hate to have to lift it over my head!

File this in the "I wish I knew at the time" bin....
My shop used to be in one of those multi-bay setups like a storage rental place, alot of small time mechanics, landscapers, ect. Some guys there bought a dozen-ish P30's at an auction and were cutting them up for scrap. I think all those engines just went to the scrap yard. The guys were of the $ now school of thought so I doubt they held on to them. I'm also pretty sure they stole about $4000 worth of stainless steel scrap from me, which is why I moved.

[cherylsm515]

you need a rear sump pan for sure. also a tilted gm adapter to get clearence for the diff to oil pan. i,am doing one with my mechanic right now. exhaust manifold flip also.
ron

[dahoyle]

Great idea for a swap, IMHO.

I'm biased, since that's what I'm building. I think that with the stock springs, you can pull it off without a springover, but I think you would be better off considering one. I know for a fact that it won't work with a J-truck, but obviously, an M715 has a bit of lift in comparison.

A great deal depends on what all you plan to modify. If you go for a bit more flex and ride quality, I think you would end up sacrificing it because you would likely have to lower your bump stops.

In any case, good luck on your build. I do have a few parts for sale if you arre interested, but I'll leave it at that as I don't want to hijack your thread.



Doug

[Mikel]

I'm working on a 6BT M715 now, but I have a completed '63 Jeep J300, a close cousin of the M715. It now has a 4BT, Dodge D60(SUA)/D70, Chevy NV4500 and my M715's NP200

My goal was to fit the 4BT in an unlifted truck. Dropping a motor in a truck that has lots of lift is easy, but can be tricky when space is limited. It did fit, but I only have about 4" clearance from the front axle to the oil pan.

[Mikel]

Going back to the subject, putting a 4BT and its 2WD transmission (from whatever vehicle the engine came from) should be an easy swap. Gearing is going to limit you to 40MPH before the engine start defueling. Much higher gearing will be needed and this will be the greatest problem in my opinion.

www.4lo.com for an excellent gearing/RPM calculator.

[militarytrux]

good luck with the swap, you also need to factor in clutch linkage and transfer case levers, dont forget about a return fuel line and tank vent.

[Swampthang]

I would consider the 700r4 over the th400. It has overdrive and a lockup convertor. Both of which will benefit the 4bt's limited rpm range.