Simple Question : Simple Answer

I believe your original question "What is more cost effective? 4cyl rebuild or V6 SWAP" ..............was answered correctly.

Now ask this question: What would you prefer factory motor wise in a Jeep of that era? And I think the V6 option would shine over the 4 cyl.

 

Jim (jpflat2a) is right, that this is a rare Jeep. Last year of domestic production for the F134, and Jeep likely made very few of them, I'd guess as few as a few hundred. But rare does not mean valuable. The CJ-5 changed very little from its introduction in 1955 through 1971. We enthusiasts see the differences between 1955 and 1971, but to the uninitiated there are many thousands of Jeeps out there that they would consider equivalent to this one. Indeed, Jeep did not even identify the year of manufacture in the VIN, so the only way definitively to know the mfr year of many of these Jeeps is through the sequential serial number database kept on this site.

And the V6 is a great upgrade ... it's one of several major upgrades that owners of these Jeeps often do ... brakes, steering, engines, transmissions, axles, suspension ... all very common, and all totally appropriate if they meet the owner's needs. CJ Jeeps are some of the most modified vehicles in the world, I would say.

One word in your original post was a little surprising - "customer." To me, this means that you are the shop owner whom the owner (customer) has asked for advice regarding how best to repair their Jeep, for as little money as possible. The customer would also like an engine upgrade, if it does not cost too much. It is admirable that you want to do what's best for your customer, and that your customer trusts your advice about what to do here. However, you do have a clear conflict of interest since it's likely the option that's best for the customer will be the worst one for you.

If I were in your customer's position and had my background and knowledge, I would expect shop charges for a V6 swap like this to (greatly!?) exceed the value of the Jeep. The only way I would consider having it done were if the Jeep had significant sentimental value to me, and I were so well off that the money was not an issue.

Note well, if you own a 1971 F134 CJ and sell it and buy a Jeep that's just one year newer, at a minimum it comes with a modern inline six that makes it fully highway capable, better axles with highway-capable ratios, better brakes, better steering ... all of the things that Jeep owners want to do to their Jeeps. So economically - purely from a money standpoint - there is no possible way that you can save money by making all these upgrades, unless you can do the work yourself.

 

Sentimental attachment is often a factor. Sorry I did not read this reply until I wrote my lengthy reply above.

IIRC there are places in the USA that will sell you a Willys 134 short block ... if no one here has a suggestion, ask for recs at the G G503 Military Vehicle Message Forums • Index page in the civilian and M38A1 tech forums.

 

I'll agree that is the popular and probably accurate concensus, but just say the word "road" should be underlined. The F-134 in many ways is satisfactory for off-highway purposes. All depends on the owner's intended uses.

I'll just add that all the above posts give very sound advice.

 

This topic has been covered again and again in archived posts, but maybe not in a single statement ... so just as information -

The F134 is fine in most (many?) off road situations. For dirt road cruising and your typical dry rocky trail, and cruising around the ranch or savannah, the F134 does fine. It can also be highway driven under the right circumstances (ie overdrive, fairly level highway, no great frontal area increase due to big tires and lots of lift, and the proper expectations). However, there are off-road situations where more power is simply better (dunes, mud) due to the power required for sufficient forward speed and wheel speed. IMO there's no significant fault to the V6 conversion (either the Buick or Chevy) other than the conversion cost and effort/engineering involved. Even the fuel economy is similar, and I suspect it may be slightly better with the 4.3L and native EFI.

So it's not all about cruising on the highway. Highway capability is also greatly enhanced by better brakes, better steering, and a more suitable final drive ratio.

 

The owner may or may not know what he has.
Yes this 1971 standard 134 engine Jeep is a rarity.
An F-134 engine means this 1971 jeep was factory equipped wih the lower geared T90 C transmission.
More importantly...
The 1971 CJ rear axle is the very desireable offset flanged Dana 44.
In this case it will have the uncommon standard F-134 ratio of 4.27.
It could also have the standard optional 5.38 differential ratio.
The Dana 44 offset flanged rear axle with factory 5,38 differential ratio is the rarest of the rare and is extremely desireable for old jeeps that are destined to be crawlers.

So the owner really needs to understand what he has to work with.

 

My experience is that the 225 V6 is that it is light years ahead of the F134 both on and off road. Unless you happen to have the not very common optional T98 transmission with an actual low gear, either 134 fair poorly in moderate to serious rock, especially steep rock. 5.38's or not. BTDT and absolutely no desire to run a 134 anywhere other than maybe a parade.

As to the original post, an LS swap would be perfect. But it ain't gonna be cheap--------- If cheap is the WORD, the only viable option is to rebuild the F head.

 

Yep............I would agree. around town and moderate highway use OK..................The one place that years ago turned me off to the 134 irregardless of gear ratio was altitude.............get it over 5000 ft and it turns into a 50 HP slug even with the high altitude kit installed.

 

I probably should have stated in the beginning that this customer uses this Jeep at the lake to "putter around". I talked with him the other day regarding the project and all the great information I have learned from this forum.

The decision has been made to rebuild the 4cyl and keep it as original as possible. Having said that, we pulled the head off yesterday and can see evidence that at least 2 of the pistons were starting to slap the head. The cylinders look surprisingly clean and I don't see any ring groove or excessive wear. We are hoping that the most we would have to go is .030 over.

Now the big question....where do I find a rebuild kit for this engine (gaskets, bearings, pistons, rings, etc..)?

John

 

start a build thread! we like pictures...before....during....and after....