engine swap

[wasillashack]

My son just purchased two FSJ's, the first is a 1981 Cherokee,258/4 speed/4wd, the second is a 1978 Wagoneer 401, TH400, QuardraTrac, plans are to get both running, establish what is needed and ultimately transplant the 401 into the 81 and using the 4 speed /tcase from the '81. We have heard conflicting stories regarding the bellhousing and transmission from the 258 being used with the 401. We know the 401 flywheel is unique to 401's. Will the bell housing and transmission from the 258 work with the 401? Any changes necessary to either? I believe the transmission is a T176 or 177, not vrified, anyone know what was the original 4 speed behind a 258 equipped '81 Cherokee? Sorry for all the ? TIA

[rocklaurence]

The bellhousing will work fine. However, to install a V8 you will need the 5" spacer between the Bell and housing. Plus, the longer input shaft that is used with the spacer. The spacer is needed to keep the trans farther back so that the shifter isnt under the dash.

[tgreese]

This is correct. A V8 used with the 258 transmission will interfere with the firewall. These trucks were originally designed for a six, and Jeep fit them with V8s by moving the engine forward, with a long transmission input shaft and a big adapter/spacer. Here's an example of the type of spacer and long input shaft used with the V8s:


viewtopic.php?t=10473

It's a big spacer.

This topic has been covered a lot in these forums if you search. Many differences between the V8 and 258 models.

You should look at your factory service manual for information about the T-17x. There were different versions, with different ratios. Jeep's naming seems inconsistent - sometimes they are T-176s, T-177s or T-178s, and sometimes they are all called T-176. Check the 1981 TSM for details. The only manual transmission used in Wagoneers, CHerokees and J10s from 1980 on was the T-17x. The J20 got the heavy duty T-18. There were Wagoneers and Cherokees with the 360 2V and the T-17x, but those have taller ratios than used with the 258, so I expect the long input shaft for the V8 will not work with the transmission you have. Likely some research in the parts books here http://oljeep.com/edge_parts_man.html will confirm this.

JMO - the medium-duty T-17x is not strong enough for a 401, especially in a heavy vehicle like a Wagoneer. Just adequate with the 258 in a CJ. Longevity depends on the driver, but I would not attempt this plan especially with a young driver ...

[Stuka]

As an owner of a J-Truck with a T176 (177, or 178, no clue which really), and it being the second one I have had in it, I would never go through the work of putting one in on purpose. Its just not a great transmission.

Besides the transmission issues noted above, the differences between a V8 and an i6 FSJ are (but not limited to):

- Radiator core support is different
- Radiator is different
- Battery mounting is different (The inner fenders may also be different, I have not had them side by side in ages)
- Engine mounts from the frame are different
- Fuel lines run up opposite sides of the frame
- Front and rear drive shafts tend to be different lengths because the transmission moves

And then most likely little odds and ends.

[wasillashack]

Thank you tgreese/stuka. Almost all my Jeep experience is CJ related. Luckily, we have two FSJ's to select parts from, as I stated in my first post. We talked today about what parts to keep from the 401 GW (donor) Jeep, we finally decided on just about everything from the firewall forward,including exhaust, axles, as well as dash parts, the tailgate and any small items that are in better shape that the 258 Cherokee S Jeep. The TH400/QT will be sold if it proves to be in working condition, all 4 bumpers are in immaculate shape, surprisingly, so two of them will be sold, most likely the T17x will be sold. It is connected to a 208 tcase, are 208s compatible with a T18? What would be the most likely source for a T18 with long input and spacer, a J truck? Or? I suppose a Dana 18 or 300 might be an option if the 208 won't work.

[tgreese]

Well, Jeep T-18s compatible with the driver's drop NP208 only come from the J20s of 1980 or later. Few years and not many built. You can run a Ford T-18 (short input shaft) if you move the transmission forward, cut a hole in the floor and heat/bend the stalk so you can reach it. As mentioned, the stalk will come up under the dash, not in the factory location. If you look at my thread linked above, you can see that the T-18 in my 1982 J20 has a long output adapter. I believe this is the identical part to the output of a Ford 4WD truck with a New Process transfer case. Pretty sure the splines won't match between the Ford 4WD T-18 and the Jeep NP208 - maybe, I'd have to do some research.

You realize that Jeep switched from passenger drop to driver drop in 1980?

I would never consider the Dana 18 for a new build. The only reason people might look at it today is to replace the offset Quadratrac, and there are better solutions to that IMO. If you go driver's drop, you have plenty of drivetrain options to choose from, all with a centered output.

I would keep the TH400/Quadratrac and run that.

[Cecil14]

The '80s T-18s were an odd spline count; 31 maybe? All the other t-cases from our rigs in the '80s used a 23 spline input. You should be able to get a new input shaft for your NP208, but it would likely cost as much as a different case. D300s from the 80s CJs will work, but they're all passenger drop. You can flip them relatively easily, though, if you want driver drop. You'd still be kinda stuck on trans. The '80s T-18s are odd and rare, the '70s units are more available but even worse for t-case options; you're basically stuck with the D20.

Another option, more expensive probably, would be an NV4500. Not gonna push it a lot, but it's something else to look into. That would also net you overdrive, which you could probably actually take advantage of with the 401.

[tgreese]

One point I overlooked - I expect the Jeep T18/NP208 combo is too long and will interfere with the gas tank in a Wagoneer/Cherokee. Even without the Jeep transmission spacer, the Ford 4WD T-18 transfer case adapter is very long and may interfere when equipped with whatever NP transfer case the Ford uses. The NV4500 is a great transmission, but I hear it's wildly expensive to purchase used. There are other truck 4-speeds that could be mated with the AMC engines, including the Muncie SM465 and the Ford T-19 or NP435. The Novak pages have discussion about mating Ford or GM manual transmissions to Jeeps without fancy adapters. The T-17x bell housing is exactly the one you need for this. These all would have the same problem as the Ford T-18, ie the shifter coming up under the dash.

[wasillashack]

We are planning on swapping fuel tanks to a Suburban? 42 gallon tank, which will help with the planned TBI conversion. We have a 454 TBI, ECM , small cap HEI and harness. Will have to buy some sensors, I'm sure. Would like to have fuel and spark control, still haven't decided on modding the stock wiring harness and buying an aftermarket stand alone TBI fuel injection harness. Any thoughts?