Difficult Swap?

The difference in performance would still be night versus day. If you rated the F head at net, it would probably come in around 50 hp.

Personally, if I'm going to the trouble/expense of an engine swap, I confide in your statement and will build something tailored to my specific needs. But that can put the expense on another level altogether. Life is a compromise. How much one compromises depends on how much money one wants to throw at it. Maybe better stated throw away on it.

 

Yes, the LS swap is very popular. I have 2 friends with CJ7's and one with a 2A that have done it, and I catch myself (owner of 4 Dauntless Jeeps) looking at them over my shoulder. Even my brother is looking at one for his Commando. But, 2 things... a swap not for the faint of heart, cost-wise and skill-wise. The FI is $2500 alone, or roughly the cost of a rebuilt 225. And, for me there is the classic-cool-rare aspect. I like the sound of an oddfire, the familiarity, and the performance is ok. If I didn't care about that, I wouldn't be driving a 70 year old heap and just buy a LJ like everyone else I see anymore on the trail. But then I would be everyone else, (not counting everyone on this forum), and I like having a unique, built by me jeep. I have to admit though, if cost was no issue, I'd think about an LS in something that has more than 3 cubic feet of cargo space.

 

Ahhh, but that's part of the challenge, especially under the hood of a flatty. SDD-Space Deficit Disorder. And I do like the low grumbling exhaust of a V8.

 

Someone once asked me why I brought a half dozen eggs on a camping trip. I said because I drive a flatty. Every inch counts.

 

having done this conversion long before the “more modern” engines were readily available, or available at all, I would say it’s a huge improvement despite the work involved. While not fuel injected or as much displacement as a 4.3 it is a great compromise between weight, vehicle balance, distributor placement, parts availability, torque and hp, and overloading stock drivetrain. Around here most 4.3’s have a ton of miles on them so need rebuilt. If I had a low mileage good running 231 that’s what I would install. If both a 231 and 4.3 needed then I would rebuild the 4.3. I will also say a 231 due to size and space is a fairly easy install compared to a 4.3.
I’m putting my money where my mouth is. I’m currently building a Buick 252 (4.1) to replace my 231. The 231 will live in another project. I’ve also built 4.3’s.
They both have their pro’s and con’s depending on budget, parts availability, and intended use.

 

Im not panning your opinion, and I see how this would be a direction you would go in if you already had the engine, spare parts for it and the familiarity. You have done this before and your jeep is already set up for this. I get it.

My point is, its 2022. The 231 is an old engine and any of them need rebuilt like any other. To swap the stock 231, un rebuilt, un modified in place of an F head, you still need everything for a more modern engine like a 4.3 or LS or whatever. New wiring harness, Bell housing, Flywheel, Clutch, Fuel lines, Clutch linkage or hydraulic, engine mounts etc.. Its really the same effort and cost to swap out a 134 as it is to swap in anything else thats readily available. The 4.3 in my 2a uses the same space as the 225 did, so its not appreciably physically larger.

My point is that to swap out the 134 for a stock, unrebuilt 231 is a similar effort to swap in a more modern engine that has more HP and FI.

To do it over again, I would have put in the most modern engine I could find because, why not? Thats what people were doing in 1985 when they were swapping in the 231's.. They also did it because a lot of those jeeps had native 225 engines that needed replacement. It bolted right in, just like the F head bolts right in place of the L head.

Nothing bolts right in place of the F head aside from some obscure stuff or the Lhead. So for cost, parts availability and the amount of work required to swap a 231 in place of a F134, you can have a more modern engine.

 

No issues with distributor cap clearance on your swap?

 

no, and it doesn't move because timing is electronically controlled. the newer engines don't even have a distributor, but coil packs. To do again, I would have gotten as new of an engine as I could find that would work in the area.

My idea is if youre going to do this, why not do it with the most modern stuff available? I have an SM 420 transmission in my CJ behind that 4.3 and its got a great low gear that I never use..Its also got a hard to find syncho..and no backup light provision. Think about a more modern engine that has more HP and doesnt need that low of a gear and you open up more modern transmissions possibly with native OD, then that opens up your rear axle selections too that doesnt need the offset D44 because of the external OD on your D18.. All this stuff is more readily available these days and doesnt cost any more money if youre buying and rebuilding all the old stuff anyway. You just need to think about it instead of copying what someone else did 10 thousand times for the past 50 years.

The original question was basically, "Is it worth swapping a low milage 1979 231 for a F134".

My opinion is no. I do feel that swapping another engine in would be. The effort to swap in a very modern engine is commiserate with the 231 swap if you were starting from scratch in price and effort. Look at the guys who have swapped in the VW diesel engines.. Thats a lot of work and super cool!

 

As far as I know (someone correct me if I'm wrong) there's no 5 speed overdrive trans short enough to work in a short wheelbase CJ. I get your point though, I've been thinking about a more modern 5 or 6 speed for my Commando. It's got all that extra wheelbase which makes things easier.

 

Yeah, I have no idea either... but then again I have the D18 with OD and all that stuff..

 

Not your preferred transmission, but a T5 with dana 300 will fit in a flat fender with an 80" wheelbase.

 

I happen to have adaptors for the T90 to BOP bell housing, and I also have a 71 Jeep Dauntless bell housing which has been drilled and tapped for a T-90 which eliminates the need for adaptors. The adaptors would fit into a large USPS flat rate, the bell housing might be expensive to ship, but I am game for that if you are.