Engine swap


Sharpest Tool
Jul 11, 2010
Western NY state 315 er
Willys Model
Willys Year:
My wife has been putting a few miles on the 51 Willys truck using it as a daily driver to work.The F head four runs well enough but the big puff of blue smoke after idling says the valve guides are worn and maybe more.It doesn't smoke driving down the road,the oil pressure is good and it leaks just a little oil,right now.
So I'm figuring over the winter to pull the head and deal with the intake valves.....But I know this is never the end and sure as shit it'll become a re ring job at the least.Looking around I see the engine parts are expensive.
I've done engine swaps so maybe it's time to think that way.Don't need a lot more power than it allready has......Obiviously the Buick V-6 comes to mind...I think the oil pump/filter is an issue,hits the front diff., in a Willys truck swap? And then there's the problem of finding a Buick clutch housing. For chump change I can buy running 2.5 4 cylinder engines from 80's S-10's.Most came with a clutch so that's less of a problem( I believe they use the common SBC housing?).Easy to convert to a carb also.Should fit right in using readily available tranny adapters.
what do you think?
I've seen F-134 complete motors sell for very little before. I've even been offered at least a couple for free in my time. My .02, keep an eye out for a spare motor in decent condition and go through that while it's out, and then swap it in when you're all done with it. I prefer to keep things stock. Parts may be expensive, but you're going to lay down $500-800 for just the transmission adapter to run a typical GM engine.
What about getting an Isuzu deisel truck and using that engine? Similar power and great milage.
I agree with cnsay... a diesel would be a good upgrade and also a bit different from all the other V6 or V8 engine transplants. It might be possible to put a Mercedes 300TD in your 51 but the weight might be too much at 650 lbs.
I second the Mercedes 300TD swap, I see them on craigslist for $300.00 all the time.
Ok folks, I've been biting my tongue on this one, waiting to see the inputs.

MY TURN!! :)

EVERYBODY always seems to lean towards the idea of an engine swap. It's understandable, BUT...why?? What's the real reason behind it??

1. The original engine is tired and you want more power.
Ok, now consider this:
a. Cost of the engine and more than likely it needs a rebuild as well.
b. It's too much power for the original equipment, so now you have to think of changing the trans, and maybe the xfer case. The original trans won't hold up long. Been there done that. Axle gearing too low, unless you're going Monster Truck with it. Frame needs rework, Steering needs rework, Brakes need rework, and on and on and on.
Speaking of brakes; let me just say that the original set up works just fine for NON re powered vehicles. Even with a V8 swap, my brakes always stopped me quite well. Ok, moving on...

2. You want a diesel for economy?
Consider most of what is above, PLUS an appropriate fuel system with all of it's gizmos and such.

You want dependability? Guess what...YOU GOT IT. How old is that original engine?? 40 - 50 years old. Sounds pretty dependable to me. You say somebody rebuilt it once and it just didn't last?? Consider the source. Odds are it wasn't built correctly.

3. You say you want to cruise at highway speeds?? Alright, so that's usually around 70 - 75 mph. Refer to point 1. The complete vehicle wasn't made for that purpose.

SOOooo...what's my point with all of this?? Easy. Your original "issue" is that the engine is puffing and you fear it's rebuild time. Yeh, probably so. A Good, Professional rebuild is going to run anywhere from 3K to 5K. That's alot of money, I know. I'm finally gonna get to take mine to be done in September. It's gonna hurt. But now figure the costs incurred for everything else you would need to do (and that means properly) for a swap. You'll end up spending less on your current engine. PLUS you can squeeze a few more ponies out of the ol' F head. A port and polish alone could net you up to 10 hp by itself!! Now consider a good three angle valve job with hardened seats - Boring, Balancing, decking. You could be looking at a possible 30hp gain easy...IF DONE PROPERLY.

If you want more speed consider an overdrive:
In the beginning...I put a Ford 302 V8 in my wagon with original trans, xfer case and the overdrive. Yes it had grunt, but cruising on the hwy still meant high rpm with those gears so with overdrive it went down the road comfortably at 60 mph. I could stab it and jump up to 80, but it wasn't pretty, and I stressed out the tranny with that extra power. Had to replace second gear twice.

In the last many years i've been running the 226 flathead. With OD on the highway the comfort level is between 55 and 60. I never put a tach on it, but i'm guessing 60mph was around 2800 to 3,000 rpm.

Once again, if you want highway speeds around 70 - 75 mph, and you start changing things, then by the time you're done, the only thing left that is Willys... is the body. You might as well by a chevy and run that down the highway.

Alright, there's my nickel's worth...again. I just want folks to think about what they want, before cutting and hacking to the point of no return. Thanks for entertaining these thoughts all the way to the bottom. :)

For you guys that have done the swaps, i'm not slamming you. Some of you have gone the distance and done it right. Hell, if I could afford and find a 2WD pickup, i'd have a field day with it. Pavel, you definitely have things going in the right direction for what you have done. I really like the 4WD Willys trucks and wagons and hate to see them cut up or changed in a manner that takes away from the uniqueness of these animals.

All I ask is that for a big change over find one that's already been hacked up and continue from that point, rather than taking another "gem" out of the motor pool. OH, keep in mind that in the original posting the last line is "what do you think?"
Thanks!! :)
I agree that repowering a Willys is more involved than just dropping in a motor if you want reliability. That is why I suggested the Isuzu deisel, the Pup had a 54 HP 2.2L engine that would have good mileage and similar power. Not sure what it weighs though.
Interesting opinions.The way this truck is used the stock 4 cylinder and gearing is adequate.Doing some measuring on my XJ Cherokee with a 4.0 says using a long inline engine will probably hit the front differential so the front suspension needs modifications. There is a rotted CJ nearby with a fine running stock V-6 for short money so I was thinking that swap.But again I can't say if the V-6 clears the front axle in a Willys truck,does anyone know if it's a bolt in swap?.By bolt in I mean you don't have to change the position of the transfer case or alter the axle location.
Rebuilding the stock F head is ok with me more or less.Being realistic ,if the engine needs a rebore with new pistons and the crank turned,plus doing a proper valve job,gaskets,it's close to a thousand bucks even when you do your own engine assembly.Money and time to do this isn't an issue really.
This truck is completely stock except for wagon wheels and radial tires.Like the guy said above they are kinda rare so any swap ,if I do one,will be very conservative.