Posted by Charlie on May 26, 1998 at 23:54:23:
I don't know of anyone who has actually done it, but I see no reason why a 4BT shouldn't fit in a M37, PW or 3/4 ton WC. The 4BT is available up to 130HP @26-2800 rpm, and 327 ft-lb @ 14-1800. It's the same length as a Hercules, ~100 lbs heavier (about the same as a Perkins 4.236). Length is NOT a problem; in fact, the necessary 5-spd will fit. However, precise choice of the 5-spd is important because the most obvious choice, the NV4500, has an excessively long tailhousing. An elusive NP540 or an easier to find Clark 280VO would be a better choice. A 5spd (or an Advance Adapters Ranger II overdrive with 0.73:1 OD ratio) is essential because the lowest ring & pinion available is 4.89. Even with 11.00R16s that boils down to 2640 rpm @ 60 mph; a waste of fuel and potential road speed. The Cummins 4B series has exactly the same bellhousing/clutch as the 6B, i.e. everything you can imagine. Specifically, all common proprietary (Ford, GM, Chrysler) patterns, SAE#2 and #3 - it's even used in a Red China PLA truck! You can even get an adapter to fit a Ford origin ZF 5 spd, which has its' own integral bellhousing. If the motor is placed with the fan 1-2" behind the radiator, there should be adequate room to clear the firewall even with a Power Wagon. An M37 should be a piece of cake. If it wasn't for the fact that I already have a Hercules 3.7DT and a Perkins 4.236 "just laying around", I'd be looking for one. Because of all the choices in rear end hookups, the power/torque picture, the nationwide parts network with a high degree of parts commonality with the Dodge pickup motors, it would be my first choice starting a Dodge conversion from scratch. It's true a gas V8 conversion might be easier (although I'm not so sure about that particularly with the narrowness of the Power Wagon and WC engine compartment), it's not much easier. I got 18mpg driving my M37 recently at 65-70mph for 300 miles one day 2 months ago. I don't think a petrol V8 would have done that. Plus the fact that these old trucks just look like the are begging for a nice torquey direct injection diesel. I'm sure I will hear cyberscreams from here to the moon, but I can guarantee you that any modern army, if offered the M37 or Power Wagon as a potential tactical truck today, would demand diesel power, and laugh at the idea of an underpowered flathead petrol six with splash-only lubrication of the bottom end! Besides, no country would buy such a fuel hog except for the US (which has gone all diesel the last 2 decades for logistical simplification and fire resistance) or an oil producer. The WC series were designed with petrol motors because in 1939 there were no small adequately powered diesel in the US then. Everything up to M4 Shermans were petrol (except for two versions with Detroit and Continental diesels); a decision that cost a lot of tankers their lives. The Red Army was ahead of its' time specing diesel for the T34 and KV series tanks.
Anyone, enough extolling the virtues of diesel; if you want one the Cummins is a great choice. If one of you decides to do it and wants some specific transmission ideas, feel free to e-mail me; I've made a study of the subject.
Charlie