“Some things here under Heaven, are just cooler ‘n’ Hell.” – Ray Wylie Hubbard
We don’t always appreciate the little things in life. It’s important to do that. Time goes by so fast. It’s important to do the things you want to do, now. And so it was that about ten years ago I decided to put a small block chevy 350 in my 1989 Jeep YJ. The tired old straight six was having issues and, well, I had always wanted a small block chevy powered jeep! The first motor was a junkyard 350 mated to a Muncie SM465, and owing to being a little inexperienced, I mistook what was likely a noise from the transmission for a rod knocking and I had the engine pulled at a local mechanic shop to replace it with a crate Vortec 350. I normally do all my own work but I was just tired of working on the damn thing. I’d had it all the way down to the frame and back in the prior ten months of weekends spent wielding a wrench. I was tired and I didn’t want to wrench on it anymore.
The end result was I may have got myself boned, but I wasn’t mad about it. It was my own fault. To be honest, I don’t think the mechanic I took it to knew any better than I did that the motor may not have been the source of the noise. It sounded just like a rod knocking and it may have been (it is very possible to have two mechanical problems at once). The Vortec 350 they installed later became hydro-locked and broke a piston (long story) and I ended up having a 383 built using the heads and some other parts off the Vortec along with a 4-bolt main block. This motor I cherish and take very good care of. Hopefully it will be around for a long time! By the way, that knocking noise is still there but now only in gear with the clutch engaged. An older friend who went to school with my dad and has turned wrenches since he got out of Vietnam told me it’s most likely a chipped tooth on the input gear of the transmission. It’s amazing how an older mechanic can really have an ear for that sort of thing. Not many people are still running those old truck four-speeds today and a younger mechanic won’t know much about them.
Anyway, I decided to tap out this blog post to share my V8 Jeep YJ experience with anyone who might be considering a V8 swap in their YJ Wrangler. It’s a very doable swap and not nearly as wild an idea as some people seem to think.
Driving a V8 Jeep
First off, unless you drive like a complete asshole everywhere you go, a V8 YJ is not nearly as crazy as some people make it out to be. My 383 I would guess is probably putting out about 400 horsepower and really starts to come alive around 1,500 RPM. Below that it has at least as much, and probably more deep low-end torque than my 4.0 straight-six TJ. This torque characteristic is no doubt owing to the cam chosen by my engine builder, but it detracts nothing from the street drivability (there is no replacement for displacement, so even with a cam a big engine can have plenty of low-end grunt) and it adds a bit of character. I recall pulling into a place one night and some good ol’ boy in the parking lot came up to me with a big smile and said, “what you got under the hood? A straight six don’t sound like that even with a loud exhaust!” My V8 YJ isn’t very pretty but it turns heads and it’s a lot of fun to drive as long as you remember it’s not a sports car! And it won’t ever handle like one. But that doesn’t mean a V8 has no place in a jeep.
In fact, the predecessor of the YJ Wrangler, the Jeep CJ-7, came from the factory with an optional V8 for some time. I actually owned one and still have the title and powertrain for it (the sheet metal and frame pretty much dissolved from rust). Mine had the 304 but with a three-speed and it was a 1976, when V8 horsepower output was becoming very abysmal due to insurance and environmental regulations that weren’t there in the ‘60s. A friend who owns a junkyard had one of the early 304 CJ-7s with a four-speed and he told me his was a real runner. I would argue that Jeep Wranglers would probably still come with V8s if it weren’t for the reputation the CJ-7 gained for rollovers, owing in part to its narrow and flimsy frame (AMC was slowly going bankrupt at the time and looking for ways to cut cost). It’s hard to recover from a reputation like that, even though the YJ has a wider and stiffer frame which makes it arguably a safer subject vehicle than the CJ-7 for a V8 powerplant. In any case, I am only speculating as to why Chrysler never produced a V8 YJ and I could be way off base. But I do know from firsthand experience that a YJ is an excellent candidate to swap a V8 into.
Axles
Right up there with, “you can’t put a V8 in a jeep, you’ll poke your eye out!” is this idea that as soon as you hit the ignition key the stock axles will explode (the internet forums are full of armchair warriors). Let’s face it, the Dana 35 is not the strongest axle for running oversize mud tires even with the straight six. Add a V8 and do a little off-roading and it becomes a ticking time bomb. However, my Dana 35 took a surprising amount of abuse! Keep in mind that your mileage may vary, but mine held up a good long time until one night I was wheeling with some people on a piece of private property a good friend owns. I wasn’t doing anything too awful crazy. I was just climbing up over a little creek bank. There was some wheel spin and then it caught traction and broke a spider gear. I would argue that could have happened even with a straight-six under the hood. I’ll admit that the 383 torquing on it all those miles up to that point may have weakened it. Still, people with straight-sixes and big mud tires bust the Dana 35 all the time, and others seem to get by with it for a long time. I think it depends a lot on tire size and driving style, and luck.
What I am trying to say is if you’re building a YJ, V8 or otherwise, you should plan on an axle upgrade anyway. If you’re doing a V8 swap and it’s not in the budget at the same time as the V8 swap, I wouldn’t worry about it too much. Just don’t plan on doing much off-roading, or anything stupid, until you have budget for axles. My next step up after busting the Dana 35 was a Ford 8.8 LSD for the rear and I upgraded my Dana 30 front with alloy shafts, bigger u-joints, and a Detroit Truetrac. With the little bit of mild wheeling that I do with my YJ, I expect this setup to last long enough to be able to sell it to someone else when I install one-tons. You can read all about my axle upgrade here.
Fitment
There is a reason the small block Chevy was called the mouse motor. It is an incredibly tiny motor given the gobs of power it can output in the hands of the right machinist. As an aside, it has a reputation for reliability, too! But given the tiny size of the small block Chevy, it’s a perfect transplant for a jeep. The Chevy V8 in my YJ actually leaves the under-hood area feeling roomier than the anemic six that it replaced. A small block Chevy fits a Jeep YJ like it belonged there in the first place.
Conclusion
Ray Wylie was right, some things here under Heaven are just cooler than Hell! I love my little 383 powered YJ! It is a ton of fun to drive and I feel like I can use it the way a jeep was intended to be used. I can put a small load of firewood in the back or even tow a little trailer and not have the skinny pedal pegged to the floor all the time on these big hills out here in Appalachia. In fact, I have fallen in love the 383 motor itself as much as the jeep. It’s just a great truck engine, given the right heads and cam. It’s got plenty of low-end grunt to get you moving and it really comes alive where you need it to for towing.