restore it or build it?

Hey Gang,

I'm furious with myself for ruining the 258 in my newly acquired 1975 CJ5, but you can't help with that (You can't fix stupid).

You can help me think through what I do next, tho, so thanks in advance.

This Jeep has only minimal rust and looks to be a candidate for a frame up resto. It has the (I'm told) rare tailgate option as well as a T18 4-spd.

Dusting my 258, however, brings me to a fork in the road. Do I order a rebuilt 258 long block and just bolt it in, preserving the original build configuration and working in the direction of a restoration?

Or do I utilize the like new Jasper remanufactured Chevy 305 complete engine that I possess as a swap-in, thereby rendering the Jeep a "conversion" whose engine doesn't match the serial number?

I realize this choice of mine might trigger responses from both purists and the "It's your Jeep, do what you want" crowd, and I welcome that. I really want to hear what you have to say.

My goal is a dependable nostalgia-machine (I've had Jeeps since I was 16 in 1958), not a rock-crawler. No lift-kits or swampers for me, just a fresh-air Jeep that works. I guess my only real question is, which works better, the original 6 or a small block Chevy?

Al from PA

 

keepit stock. the 258 is a rock solid engine and the conversion you are looking at doing is a whol lot of work.

 

Thanks, HH

Would you obtain a rebuild or a "remanufactured?"

 

IMO, 258's are dime a dozen, just go pull one out of a Jeep, and rebuild it if it's not going already. I know they pop up locally for sale, sometimes even free. That is, unless you don't upgrade to a 4.0L from a TJ or such. I don't know what is required, just I know they are the same block.

 

I bought a core engine for $150 and had it rebuilt at a local shop for $700. Sold the Webber carb off the core for $100 so I was not out a lot of cash.

 

If you are going for nostalgia machine I'd keep the original engine. I had the same choice of upgrading to a 360 or re-doing the 304 and decided to keep the AMC 304.

 

I have owned multiple 258 Jeeps and my 74 CJ with the V-8. I happen to love the V-8. So much more torque and power than the 258 six. Keep in mind, all of my 258's were stock with exhaust systems being the only upgrades. Sure you could build up a pretty strong 258 ,as I am sure many guys on here have done, but there is no substitute for cubic inches!! I just happen to be a big fan of V-8's and have no love for the 6's.....

This seems like a good time for you to make a big change considering your 258 is shot.

 

I think you should stick with the 6. I do think there is something to be said for the newer 4.0 liter with fuel injection. Perhaps a stroker motor? There was a guy on GL4X4 that was selling stroker motors at what seemed a reasonable price.

 

I think the only point in the 305's favor is that you have it on hand. That, and Chevy hop-up parts are cheap and available. Every swap involves more work than just bolting up the adapter ... you'll need mounts, and all the accessory hook-ups. And you'll end up with only 47 cid more than the 258.

There were a lot of 258s made, and good ones are cheap and readily available. Look around and you should be able to find one private party for very little money.

If you want something a little more wild, you could swap in a 4.0L HO engine, with its MPI, or build a stroker engine. An engine built with a 4.0L block will be lighter, fit in with no adapter, mount, or cooling changes, and should easily produce as much or more power than a stock 305.

IMO the 305 will be no more reliable or durable than an AMC inline 6. Both the 258 and 4.0L have a reputation for toughness and longevity that speaks for itself. Look at all the 200K and 300K XJs out there with 4.0Ls ... stock parts are inexpensive and widely available too, so the Chevy has no great advantage in that category.

I'd probably keep the 258 and go with the 4.0L HO head, MPI, mild cam, and drive it.

 

Thanks to all of you for taking the time to give me your points of view.

Timgr, I hear you that availability is the big thing going for the 305.

Perhaps a power boosted 6 would achieve all my goals: It would still be a Jeep, it would be a "bolt back" in instead of a "conversion," it would perform reliably and with a bit more punch than the worn out 6 it came with.

Thanks everyone. Happy to hear more opinions if you got 'em.

Al from PA

 

I'd like to throw a spin on 1975CJ5T18256's question:
What if it were a Chevy 350 he had laying around and not a 305?
Would it then be worth the conversion?

 

It would provide a better reason if you wanted to swap for more power, but I don't think that would be enough to sway me. Some people are fans of the Chevy motors... I don't think there's anything special about them except that they are plentiful and comparatively cheap to fix or build up.

From that era, the 258 w/ CR T-18 is the most desirable factory setup IMO, esp. with 4.27 axles. If I were looking to buy a CJ-5, that combination would be worth a premium price, and I'd probably pass on a CR T-18 that had been converted to SBC power. My preference. Any swap, particularly a V8 swap, would make me wonder about both the execution of the swap and the kind of (ab)use the Jeep had been subjected too. I can understand swapping out a F134 that can't keep up normal traffic, but a 258 will move one of these Jeeps at super-legal speeds easily, and I have the speeding tickets to prove it. JMO.

 

Personally, I'd go with a 4.0 HO. It has puts out substantially more horses than the 4.2l. 190 vs ~110. You will definately notice the difference. It still peaks it's power curve at low RPMs but it's a huge improvement over the 258 with minimal changes to the existing setup. I found a good one with 90,000 on it for $300.

Then again I'm partial to straight 6's and not SBCs.

 

Thanks forthe extra insights, and for the reassurance about the 258.

I'm gonna' begin thinking along the 258 path.

Which makes me want to ask- how hard to add power steering?

Al from PA

 

Just my 2 cents - I just did a frame-off resto on my 79 5 w/AMC 304. Had the original block rebuilt. It runs like it just rolled off the showroom floor, and it was very easy to drop back in the Jeep. Also, if I ever NEED to sell it (I'll never WANT to sell it) a numbers-matching original will fetch much more than a conversion. And if I were a buyer, I'd much rather buy a CJ with a rebuilt 258 than a Chevy V8. My buddy has a 7 with the 258. I may blow his doors off on the street, but he always keeps up with me off-road and gets better mileage. Last point - The world needs more stock, original, numbers-matching cars. Conversions, hop-ups, rods, and customs have their place, but my heart really gets racing over a classic stock original vehicle. Keep it stock!

 

i would go back stock, im a chevy man myself but the 305 was what i believe a lacking motor, i have one in my 84 k10 and its ok but it needs something more and the #'s matching thing would be nice.

 

i am with mgtmel and Huntman. if you arnt looking for something to go crazy with and want to cruise it around then i would keep the numbers matching. nothing like an all original classic.