GM Engine Swap

[69gladiator]

My son and I had the GEN I 232 in his 69 Gladiator rebuilt a year and a half ago. The rebuilt engine has been a disappointment . It has developed a tick in the head. The machine shop has not been entirely helpful. We are looking into scrapping the engine and replacing the entire drive train or at least the engine with GM components (small block V8). The truck has a T-18 and a D20 in it now. We are wondering if there is a good tutorial on the process. Novak and Advanced Adapters provides some useful information but we want some step by step info to avoid reinventing the wheel.

[tgreese]

Maybe I'm not the best person to start this, but I'm willing to write a response.

I don't think there's a single source that will help you. I believe Advance Adapters sells a book about engine swaps that covers Jeeps, but looking at their site, I don't see it advertised any more. Rather than a single source, I think you'll need to do the research yourself and read everything you can find about these trucks and people's experiences with swapping engines. From a purely practical point of view, you'd be much better off to sell the truck that does not meet your needs, and buy a truck with the equipment that does, rather than try to make this truck become something that it's not. I've suggested this before, and typically this advice has not been well received... so be it.

If you are dead set on a swap, the first thing I would mention is that there are many differences between the inline six equipped trucks and the V8 equipped trucks. This has been discussed a lot at IFSJA and here - you should research it. The T-18 for the sixes and the T-18 for the V8s are not the same - they are different lengths, so if you adapt the six T-18 to a V8, the shifter either comes up under the dash or the engine interferes with the firewall. You'll need a plan to deal with this.

Use Google or Bing to search for old posts here and at IFSJA on this topic. Enter "site:fsjnetwork.com <your search terms>" Swaps have been discussed a lot, and the old forum posts are your reference that will provide the background information that you want. I think the closest you will come to a tutorial is finding someone (through search) that has done a swap similar to the one you want to do, and talking to them. Otherwise, part of the work is doing the research to figure out what you need to do. It's work ... there's no way around that, but that's what's required.

[tgreese]

Thinking about this a little more, I wondered about an easy engine to swap in, in place of the Gen 1 232. As you know, the Gen 1 232 is different from the later 232 and 258, which have the "unified" AMC bolt pattern. So the later six cylinder engines will not bolt-in to replace the existing 232.

With your 232, you have a T-18 input shaft that is (almost) specific to that application. Looking at the parts book here: http://oljeep.com/parts_man/62-73_FSJ_P ... g_w_bm.pdf - Your T-18 has the 941110 input shaft. Jeep had many different configurations for the T-18, something like a dozen. However, the parts book says that your T-18 uses the same input shaft as 1972 or earlier 258 sixes. So you should be able to bolt-up one of these early 258s with its bell housing (1971-2 only, flange-style crankshaft, I presume). It is possible that the only difference between the 1972 or earlier T-18 for your engine and the later T-18 for the 258 is the diameter of the pilot tip. If this is the only difference, then you could maybe make a custom pilot bushing and use the existing input shaft with the later "unified" bellhousing, Jeep PN 3215152. The input shaft is group 6.060-1, the plate adapter is 6.053-1, and the bells are 5.054-1.

Now, if you can adapt a '72-up 258 using the unified bellhousing, you can also adapt a Jeep 4.0L engine, which would give you V8 power and should be a lot easier swap than a V8. All these engines use the Jeep T-18 927829 plate adapter between the bellhousing and the Jeep T-18. I strongly suspect that the input shaft stick-out is correct for the unified bellhousing, but the pilot tip is different. The only way to tell for sure is to measure what you have, and buy or borrow the parts from one of the later engines and compare the bell depth to the bell you have. Maybe if you have the measurements of the input shaft, someone here can measure a later six cylinder input shaft and tell you if it will work.

Another possibility is to put your T-18 output shaft in a Ford T-18, and bolt that to your transfer case, move the transmission forward so the V8 clears the firewall, and bend the shifter stalk in a dog-leg so that it clears the dash. The Ford T-18 can easily be adapted to AMC, Ford or GM engines. Novak has some info about this. This is probably easier in terms of mating the engine and transmission, but it becomes more work in connecting all the other stuff like shifters, drive shafts and clutch linkage. Plus you will need to take the Ford T-18 apart and put it back together with the Jeep output shaft, and do some drilling, tapping and hole filling in the Ford T-18 case.

So there are a lot of possibilities to explore if you are serious about swapping. You will have lot of research to do, and you'll need to measure the parts that you have to see what will work.

[69gladiator]

My bad, the truck has a T14 in it.At the time of the post I had a T18 on my mind because I was buying parts for my brother. Again, sorry about the misinformation. You point about installing a Jeep 4.0 is a very good one. With some tweaking it can provide a lot of power. In your opinion if we go the 4.0 route, what would be a easy swap as far as the transmission and transfer case is concerned. I believe that we can adapt the T14 and D20 to a 4.0.

[tgreese]

Jeep continued to use the T-14 in the CJs with the 232 and 258 through 1975. These CJ T-14s use the unified bell 3215152 I cited before, so they would bolt up to a 4.0L. The unified bell does not have a provision for a crank position sensor, so you'd have to modify it to accept one using the 4.0L flywheel, or use the HESCO kit that puts a toothed wheel and the CPS on the front of the engine. I'm not an expert on T-14 parts, but I'm pretty sure the pre-72 J-truck T-14 is different from both versions of the T-14 in the CJs and Commandos (ie pre-72 225 V6 and post 71 "unified" AMC engines) and what was used in the trucks 72-76.

Anyway, experience has shown that the T-14 is not up to V8 power, and I do not think it would last long behind the 4.0L, especially a 4.0L that has been built for power. The simplest change would be to use a T-15 instead, which would be plenty strong. The output splines on the T-15 are different from the T-14 (6 instead of 10) so you'll need the T-15 output gear (bull gear) along with the transmission. Noval has a chart that shows the gear numbers for the Dana 18 and Dana 20 https://www.novak-adapt.com/knowledge/gear-table/ The T-15 is 1 5/16" longer than the T-14, so you may have to move the cross member and change the driveshaft lengths.

There are not that many transmissions you can use that won't require adapting on both the engine and transfer case end. A Jeep T-18 from a 72-79 CJ, 72-73 Commando or 77-79 258 wagon or truck would work, but they are harder to come by, more expensive when you find them, and heavy shifters - not everyone wants to shift a truck 4-speed. The T-15 will shift almost the same as your T-14, and while not plentiful, there's limited demand for them as an upgrade. There's nothing else that will bolt to both the 4.0L and to the Dana 20 without modification (correction - see below). If you are ready to spend the money, any of the truck 4-speeds could be adapted with aftermarket parts, but the truck 4-speeds are all big and heavy and take some muscle to shift.

[tgreese]

On second thought, the T-150 from a '76-79 CJ would work too. Stronger than a T-14, not as strong as a T-15. It too would need its own output gear to mesh with the Dana 20. See the Novak chart. The T-150 is only 5/16" longer than the T-14, but the bell and input is 1" shorter, so OAL looks to be about 11/16" shorter than the T-14 combo.

The T-15s you'd want would be from a 1972-75 304 V8 CJ-5 or CJ-6, a 1972-73 304 V8 Commando, or a 1977-79 258 J-truck, Wagoneer or Cherokee.

Be sure to get the bell and the clutch linkage with the transmission, if possible.

The T-150 is a Ford transmission built on license for Jeep by Tremac. The T-14 and T-15 are Borg-Warner transmissions.

[tgreese]

Here's a T-150 that might stil be available - http://www.jeepforum.com/forum/f126/t15 ... a-3865689/

[racerx12003r1]

If you lived closer to NC, I have a 258 with less than 20,000 on it that i pulled to do a 5.3 swap that needs a new home.

[o0elvis0o]

From a purely practical point of view, you'd be much better off to sell the truck that does not meet your needs, and buy a truck with the equipment that does, rather than try to make this truck become something that it's not.

Why do you think a person who loves vintage Jeep styling is better off getting a non-Jeep vehicle rather than modifying their Jeep to meet their needs/wants?

I am going for the LS swap myself. I love the Jeep's looks and interior. So does my wife and all our kids. But the carburetor and poor gas mileage are problems we don't wish to live with. Our intents are to drive the hell out of this old Jeep, and do it comfortably. Rather than fiddle with adapting a fuel management system onto an engine that isn't native to it, I think the LS swap wins hands down for our situation.

You may have explained your thoughts on this in detail in another post and I just haven't seen it yet. If so, could you give me the link? I am open-minded and would like to understand your stance. Thanks, tgreese!

We are looking into scrapping the engine and replacing the entire drive train or at least the engine with GM components (small block V8).

I haven't seen an 'official' write-up but looking at build threads and some of the other very detailed posts where someone is doing an LS swap I think every angle and question has been answered. It seems that way from the outside, at least. I am saving up for the donor vehicle to get my swap started. If you get started before I do I would love for you to document the details of the process here. I will do the same with mine. However, I will swap over a GM manual transmission as well and have to deal with all the adapters for that and the custom length driveshafts.

[tgreese]

I never suggested a non-Jeep vehicle. If the OP wants a Jeep truck, he can find one equipped to meet his needs. Indeed, it would be significantly easier to find a replacement '69 Gladiator with a V8 than one with a six. And going a few years newer will glean many significant upgrades, with little change in appearance - and the appearance issues that do change can easily be modified to look like the earlier models.

Someone wanting to swap from AMC six to AMC V8 comes up pretty often. In these cars, it's not very practical IMO. There are a lot of differences between the V8 and inline 6 equipped FSJs, and the V8 cars outnumber the sixes by maybe as much as 50 to 1. It seems a little quixotic to take on such a conversion, when there are so many other used Jeeps out there. Leave the six cylinder trucks to the owners that want one equipped that way.

Same with converting from manual to automatic, or vice-versa. Just find a car equipped the way you want, and swap cars. Especially if you want an automatic, there are many many more automatic-equipped FSJs available than not.

The complete drive train swap to modern SBC with a modern GM overdrive automatic has a lot going for it ... I'm not really arguing against that. However, it will cost a lot in time and money, and it will take years (if ever) to make back the savings in operating costs compared to driving a J-truck or Wagoneer with factory equipment. I think the gas mileage argument simply does not hold water - you will never achieve the MPGs of the donor, simply because the antiquated chassis has so much more drag. Your gas mileage will improve, but it won't be as good as the donor. Do your back of the envelope calculation, and see how long it will take to make back your investment from increased fuel economy. I do agree that modern fuel injection, like the SBCs have, is a big upgrade. But it is possible to have turnkey fuel injection and not do a drive train swap... If you have much higher peace of mind with the SBC swap, I can understand that.

Often owners set out on such upgrades thinking they can carry it off quickly and at minimal expense. JMO - such projects seldom end up as cheap and as quick as they think they will be, and there is significant economic and emotional risk involved. Very often such projects end up unfinished, after significant investments of time and/or money - often at no fault of the owner. Life can interfere. Unfinished car projects usually sell for a tiny fraction of investment, and selling off the pieces of a project - to minimize the loss - can take a long time and require a lot of effort. Indeed, buying an unfinished project can be a terrific bargain for someone with the time, the skills and the money to turn it into a running vehicle, or who is willing to sell off the valuable parts of the project at a profit, and with sufficient emotional distance to scrap what's not valuable.

My main point has been that, if you value your time and money more than the emotional and aesthetic appeal of owning a specific old Jeep, you cannot justify a drive train swap. Breaking the emotional bond with a specific car can be difficult... but IMO that's the appropriate action in most cases.

[o0elvis0o]

Awesome response. Thanks!

I see what you were thinking and completely agree. I didn't know the six to eight was such a complicated swap. I see now where you are coming from about leaving a six a six.

You certainly have a deep understanding of the ins and outs of these old Jeeps. I really admire that.

[racerx12003r1]

A 6 cylinder to GM swap isn't that hard. With a little imagination and help from your local parts house, you can hook a Gen 1 or Gen 3 small block to a 258 radiator with no problem, and believe me, it will keep it cool. Mine runs at thermostat temp all the time, whether its 195 or 165 degree thermostat in the middle of summer on the trails.