Flattie Follies
I've read your magazine for a few years now and love it. I just decided to part ways with my '03 TJ. I'm currently active duty in the Army and just returned from a 12-month tour in Afghanistan and am currently serving another 12-month tour in Egypt. While over here I just found a '46 CJ-2A for $500. So, with a few quick emails to my dad and buddies it's being picked up this weekend.
I haven't had much contact with the guy I'm getting the flattie from so I don't have as much info as I'd like. Apparently the engine is in pieces in the garage, yadda, yadda, yadda. So it looks like I'm not getting the stock 134 L-head with the Jeep, but the rest of the original drivetrain (as far as I know) is intact. I've been looking online and can't seem to find hardly any L134s for sale, so I've been looking into engine swaps.
I've settled on a GM 4.3L V-6 as my main option. I would like to keep the flattie very simple and as close to stock as possible. Is this an easy swap that can be accomplished with few modifications? I would also like to drive the Jeep every now and then on the road, so I'm assuming the old Go Devil would have had a tough time keeping up anyhow.
Also what would you recommend upgrading drivetrain-wise? I would like to keep the original axles, but I'm looking at using maybe 33-35-inch tires and doing a 1-2-inch suspension lift with a spring-over.Chad Burnumvia e-mail
Sounds like you're planning a pretty smart little buildup. A 4.3L will be a great engine for a flattie. There are plenty of aftermarket motor mount kits available through Advance Adapters (advanceadapters.com) and Novak Adapters (novak-adapt.com) for starters, as well as conversion bellhousings and parts to mate the V-6 engine to the stock T-90 tranny and exhaust headers if you need them. However, I'd recommend using the stock 4.3L exhaust manifolds. Depending on which 4.3L you go with, you'll have some options as far as injection and wiring. The simplest method will be to nab a 3.8L (the smaller version of 4.3L, nearly as good, came in early '80s GM cars) or an early 4.3L with a carburetor and just slap it in there. If you go injected, steer clear of the later Vortec engines with the distributorless ignition and the coil-on-plug setup because the aftermarket support for these engines isn't as strong as the earlier Vortec V-6 engines.
The only other bummer you'll have with the 4.3L would be a little bit of distributor-to-firewall interference if you keep the stock large-cap HEI distributor. However, you can make it work with a hammer, or just swap to an aftermarket small-cap electronic distributor (Accell, Mallory, MSD, etc), as long as you're not running a computer-controlled ignition.
As for the drivetrain, I'd stick with the stock T-90 tranny. At least for a while. It'll hold up if you keep it moderately sane. The same is true for the Spicer 18 T-case. I'd think about eventually adding a Warn, Saturn, or ATV Mfg. overdrive. Check out all three at hermtheoverdriveguy.com. Herm Tillford offers a lot of early flattie stuff and does a great job rebuilding gearboxes. It's a good company to know about if you're building a vintage Jeep.
Axles I'd keep stock as well. You've got 5.38 gears in the Dana 25 front and Dana 44 rear. Lockers? I wouldn't. As soon as you lock up these axles, they start chucking their guts unless you upgrade the shafts, which can be costly. At the very most, I'd add a locker to the rear Dana 44 and would whip up some sort of full-floater conversion kit that replaced the stock 10-spline shafts with later 19-spline or aftermarket 30-spline shafts. Again, I think Herm has something on his site at atvmft.com for this.
As for tires, I think you're making a mistake trying to go all the way to 35s. That is, unless you want a full gonzo trail killer. Put that on the back burner and focus on having fun with the Jeep first. I'd suggest a simple spring-under suspension. Check around as there are lots of bolt-on kits. Replace the factory C-shackles with later ones if it hasn't already been done. As for tires, you can fit 32s with a 2-inch lift and you won't have any driveshaft issues. When or if you do finally pull the trigger on bigger tires and a spring-over, keep in mind that using 1-2-inch springs on a spring-over will be circus-wagon tall. Stock YJ leaf springs will give you plenty of room in a spring-over, but you'll have bad axlewrap and the springs will be in the way of the steering components.
I think a better long-term suspension plan would be to convert to YJ spring perches and then run a 3.5-4.5-inch YJ spring-under suspension. That way your steering is kept simple, you won't have any axlewrap issues, and you'll still have as much flex as you would with a spring-over and stock springs. It's a way better setup.