omega_rugal Posted April 24, 2017 Share Posted April 24, 2017 i just found a 1970 J20 sitting on a garage collecting dust, the owner says the engine is busted (inline 6 4.2) someone tried to fix it but couldn`t and just left a bunch of parts in the box, so it may not be a complete anymore, the tranny is gone but it was an auto, very little rust considering it`s age, the only thing i gonna need to buy/make is the grill, i really like this truck but unless i can make it run again there`s no point in getting it, it`s very cheap btw the current owner says it`s been sitting there for like 15 years and wants to get rid of it, it`s a good truck that doesn`t deserve to end in the crusher... like i said the engine is an old 4.2, probably will not run again, so the idea is to put a modern 4.0 (sorry my ZJ, i`m looking at you) with a new tranny... but what are my options? i mean for an auto AW4 is the way to go but i prefer manuals all the way, i have read somewhere that the old manual jeep trannys "bolt in" to the 4.0, if so what are my options? Link to comment Share on other sites More sharing options...
jpnjim Posted April 24, 2017 Share Posted April 24, 2017 The AMC 6 changed bellhousing bolt patterns between 1971 and 1972, so if that L6 is original, the trans will not bolt to a 4.0L. The 4.0L shares bellhousing patterns with *66-91 AMC V8, and 1972+ AMC L6's. So a 1970's/80 Jeep T-18, or T176 4 speed will bolt up to a 4.0L, but you'd have to do something about the Crankshaft Positioning Sensor, since the 4.0L MPI needs one to work. FSJ T-18's used super long input shafts & extended bellhousings to get the transmission shifter out from underneath the dashboard, I don't know if the T170 series transmissions in FSJ's did the same thing or not, so keep in mind if you go with a non-FSJ transmission you might have to get creative if the transmission shifter pokes out from under the dash. T170 series Jeep transmissions are made by Tremac, they are decently strong, but far from bulletproof in a full size. 6 cylinder gear spacing is similar to our AX-15/NV's, without the overdrive. T-18's are strong, but with wider spaced ratio's, my old FSJ had a non-syncro 6.32 first gear, so it was a glorified 3 speed, starting in second gear on the street. I'd probably just use an AX-15, or NV3550 5 speed overdrive trans, and try to keep it alive in while pushing 1000lbs more Jeep around. I don't have a 1970 Jeep Factory Service Manual handy, but the 1969 book says ALL Gladiator L6 (232) automatics came with 4.27 axle gears, so the overdrive would be helpful. Also, double check the year, the J20 name wasn't used until 1974, lots and lots of changes were put in place from 1970 to 1974. *66-91 date for AMC V8's is for the later thin wall V8's, and does NOT include the first generation AMC 327 Vigilante's that were held over, and still used in Jeeps up until at least 1969. The first generation AMC V8's had it's own bellhousing pattern different from the later V8's, and the L6's. Link to comment Share on other sites More sharing options...
omega_rugal Posted April 24, 2017 Author Share Posted April 24, 2017 i can`t confirm the year model, not even the owner knows for sure, also doesn`t have a grill to compare it to, but IT does have a J20 logo on the drivers side... so it`s post 1974? no title, VIN is no legible (maybe if i search for other parts where it may be?)... it`s old and i`m no expert in telling them apart just by looking at them... anyway that engine either factory or not, is going to be discarded, i do have a HO i can use but has the less-than-impressive 42RE auto, i`m looking for an old 4 speed, or why not, a 3 speed manual, i don`t plan to race the truck i`ll see if i can get another look at it today.... Link to comment Share on other sites More sharing options...
jpnjim Posted April 24, 2017 Share Posted April 24, 2017 Big big differences from 62-73 and 74+, 1974+ has a lot of improvements, easiest way to tell is to look at the wheels, almost all 62-73's have a 5 lug (on 5.5") wheel pattern (1/2 ton and 3/4+ ton) 74's went to 6 lug for the J10's and 8 lug for the J20's. 62-73 J-Trucks (not Waggy's) had terrible 2" wide front leaf springs and were spring over axle up front. 74+ J-trucks went to the (much better) 2.5" wide Waggy style front leafs, and were SUA. 74+ had open knuckle front axles 62-73 had weaker closed knuckle front axles. That should narrow it down for you, there were also big changes in 1980, with the front axle drop going from passengers side to drivers side, and the top of the cab losing the built in sheet metal 'visor'. If there's no VIN, look for an aluminum plate under the hood, or on later Jeeps, an emissions sticker, the sticker should give a model year, the aluminum plate a serial number. Link to comment Share on other sites More sharing options...
ftpiercecracker1 Posted April 24, 2017 Share Posted April 24, 2017 I didn't see anywhere in your post a burning desire to keep it all "jeep". Have you considered a simple carburated small block Chevy and turbo 400/350 combo? I have the exact setup in my j10 and it goes pretty good. I don't think a 4.0 will be to much fun in a j-truck, to heavy, but thats just my opinion. Either way I'd love to see some pictures. FPC. Link to comment Share on other sites More sharing options...
omega_rugal Posted April 24, 2017 Author Share Posted April 24, 2017 it has 8 lugs AFAIK, that narrows it down... Have you considered a simple carburated small block Chevy and turbo 400/350 combo? if i had them why not... Link to comment Share on other sites More sharing options...
Eagle Posted April 24, 2017 Share Posted April 24, 2017 The VIN should be on a plate on the dashboard, in front of the driver. IMHO it doesn't matter. The engine is trashed, and the tranny is gone. So start over -- pull a complete engine/tranny/transfer case out of something and plug it in. If a CPS is the only issue, last I knew (which was a few years ago) Hesco offered a kit to mount the CPS on the front of the engine and read the signal off a spacial vibration damper. Or -- just buy an electronic distributor, run a carburetor, and forget ever having to change a CPS ever again. A J20 was a heavy-duty truck. If I had one that needed an engine, I'd look seriously at an AMC 360, 390, or 401. Link to comment Share on other sites More sharing options...
omega_rugal Posted April 24, 2017 Author Share Posted April 24, 2017 So a 4.0 HO will not cut it? Link to comment Share on other sites More sharing options...
jpnjim Posted April 24, 2017 Share Posted April 24, 2017 So a 4.0 HO will not cut it? Depends on what you want to do with it, if geared right, a 4.0L J20 would be a decent around town truck. I had a 73 J4000 (3/4 ton) as a daily driver for a few years, with a wide ratio granny gear T-18 & 4.10 axles, even with a decent 360 (torque cam/intake & 4v Holley) it was still going nowhere fast. It's easy to forget how many old full size trucks went their whole lives with L6's chugging them along, in all honesty, other than holding the shifts out a few more RPM's, I don't a think 4.0L swap would have changed the slow moving, stump pulling personality of that truck. Well, that and maybe the 8MPG might have improved to 10 with MPI lol. :doh: :yes: Link to comment Share on other sites More sharing options...
omega_rugal Posted April 24, 2017 Author Share Posted April 24, 2017 if geared right, a 4.0L J20 would be a decent around town truck. that`s what i want it for... Link to comment Share on other sites More sharing options...
jpnjim Posted April 24, 2017 Share Posted April 24, 2017 My old 73' granny trans & 4.10's = big heavy and slow even with a fresh 360, bigger cam, Edelbrock Performer, dual exhaust & Holley 750 vac. omega_rugal, you said the one you're looking at doesn't have a grille? Does it have the sheetmetal that would normally be below the grille like above? Link to comment Share on other sites More sharing options...
omega_rugal Posted April 24, 2017 Author Share Posted April 24, 2017 no, it has no lights and i can see the radiator... Link to comment Share on other sites More sharing options...
DirtyComanche Posted April 25, 2017 Share Posted April 25, 2017 So a 4.0 HO will not cut it? It's won't be a speed demon. But it will be way better than stock... I've debated throwing a 4l in my 76 because the 258 is seeming less than healthy. Link to comment Share on other sites More sharing options...
jpnjim Posted April 25, 2017 Share Posted April 25, 2017 OK then, someone must have needed a new nose, that sucks. You could probably fab some sheet metal panels up to support the headlights, and hide it with a later full width plastic grill. Link to comment Share on other sites More sharing options...
omega_rugal Posted April 26, 2017 Author Share Posted April 26, 2017 i would like to make something like a rhino grill, the later grills meh... the owner is not home, but i`ll see if i can take a pic from outside, it`s a private property... Link to comment Share on other sites More sharing options...
omega_rugal Posted April 27, 2017 Author Share Posted April 27, 2017 finally the door was open yeah it`s too small, taken from far outside, you can see the lack of grill, four holes for lights that hint to a pre 70 era but i have seen full width grills on top of those so not conclussive another clue: front diff drops to the drivers side... and leafs are below the axles...so it`s more close to an 80`s model? Link to comment Share on other sites More sharing options...
FrankTheDog Posted April 28, 2017 Share Posted April 28, 2017 Does it sort of have a visor over the windshield or does it look more like a wagoneer in that area? If it has a 258 in it it will have had a Chryler 727 TorqueFlight transmission. It is an 80-88. The sheetmetal you see surrounding the radiator opening didnt change from 65-91, you can put any style grill from any year FSJ on it. Link to comment Share on other sites More sharing options...
DirtyComanche Posted April 28, 2017 Share Posted April 28, 2017 If it has a 258 in it it will have had a Chryler 727 TorqueFlight transmission. I believe if it has a Quadratrac it will have a TH-400 even if it's a 258. Link to comment Share on other sites More sharing options...
FrankTheDog Posted April 28, 2017 Share Posted April 28, 2017 TH-400 is 79 and older passenger drop. TF-727 is 80 and newer drivers drop. Link to comment Share on other sites More sharing options...
omega_rugal Posted April 28, 2017 Author Share Posted April 28, 2017 Does it sort of have a visor over the windshield or does it look more like a wagoneer in that area? it the pic is not very noticeable but there`s a visor... Link to comment Share on other sites More sharing options...
omega_rugal Posted May 12, 2017 Author Share Posted May 12, 2017 update: is gone, the guy raised his price wayy too much, someone must have tipped him about it or got a better offer... i`m seriusly considering getting a beaten up wagoneer and cut her up to make a gladiator... Link to comment Share on other sites More sharing options...
omega_rugal Posted May 24, 2017 Author Share Posted May 24, 2017 last update yes, someone else bought it and is restoring it, painted it gold and... slapped a chevy 350 in it... oh and mistery solved, it`s an 84... Link to comment Share on other sites More sharing options...
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