my 401 is TIRED... thinking about a swap

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mgbreis
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my 401 is TIRED... thinking about a swap

Post by mgbreis »

I've had my '78 for over a year now, I don't post much but I really just enjoy the heck out of owning this jeep. I've done a ton of work to it just to get it going after it was nearly scrapped, most recently I replaced the chain in the quadra trac. I'm hoping for some snow this winter so I can experience the traction! Anyway, the 401 runs okay for just cruising around town and out to the fishing hole, but it is definitely tired. Leaks like a sieve and smells like unburned fuel at all times. I haven't bothered with a compression check but I have two plugs that foul repeatedly, it smokes some and it doesn't have a whole lot of power. Not a huge deal because I'm not interested in a serious off roader or a pulling rig. We basically just drive it around as a "vintage wagon", and that's about all I ever plan to do with it. I COULD rebuild the 401 and call it good.

But... man I would love efi and an overdrive...

From what I've read I could probably keep the quadra trac and the offset axles and go with either an LS or a vortec 5.7 with a 700r4/4l60e via an adapter that Advance sells. Is there any other combo that makes sense for a cruiser like I'm talking about? For example, I'd love an overdrive manual transmission. Is there any combo that could use an AX15 without $2,000 in adapters? I'm not too charged up about swapping axles, but I suppose that wouldn't be too difficult if necessary to change the pumpkin locations. Anyway, sorry to ramble, I've done a lot of searching and reading but the combinations and variables get very confusing!
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Stuka
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Re: my 401 is TIRED... thinking about a swap

Post by Stuka »

Unburned fuel just means you have a carb issue. I would also do a compression test, to see if it actually is worn out. Carb issues are easy to fix. Either with a new/rebuilt carb, or EFI.

You cannot put a QuadraTrac behind a manual, it will have a very short life (The shock loads will kill it).

Swapping in a whole different drive train is always an option, but its a time consuming and expensive solution. The other question is do you have emissions where you live? As that makes an engine swap more difficult as it limits your options. A junkyard engine can work, but you have to put all the emissions equipment that the engine donor came with.

So if it was me, I would go the simple route first, which is see if you can get your current stuff running well.
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mgbreis
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Re: my 401 is TIRED... thinking about a swap

Post by mgbreis »

No emissions (rural Nebraska). You're right, I'm a little lazy posting this without doing compression check, etc. first. However, in my defense, when I see two spark plugs that are caked in grease it's a fairly good sign the engine has an issue. I would imagine most 70's v8 engines with 100,000 plus miles are a little worn. I've a got two cars already with engine swaps, so I have an idea of the difficulty involved. I just don't have much knowledge of jeep specific stuff. My Dad has a Dana 18 I can have, but that doesn't seem to be a great solution either. I've been kicking around the idea of foregoing the overdrive and just using an adapter to connect a 4.8 to the th400. I had a tahoe with the 4.8 and I think it'd make a nice driver with that engine.
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Cecil14
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Re: my 401 is TIRED... thinking about a swap

Post by Cecil14 »

If you're going to spend any money on an adapter, you might as well skip that and ditch your whole driveline. You can get a modern OD trans and fulltime tcase (NP242 comes to mind as a decent case) for what the adapter will cost you. If you're going to swap anything, it makes no sense to keep any of the old. You're just killing yourself in efficiency losses and adapter costs.

Not sure if you can throw a manual in front of a modern fulltime case or not, I can't think of seeing them factory that way. As Stuka said, most fulltime cases don't like the shock a manual provides, they survive due to the cushion from the auto.


aa
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Fast Eddie
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Re: my 401 is TIRED... thinking about a swap

Post by Fast Eddie »

My J20 was a QuadraTrac and PO swapped out a NV4500 and Dana 300 T/C. Lots of work and $$$ but it IS a very nice combo to drive now! Axle in rear needs to be swapped for manual and of course a modified rear drive shaft. Just FYI!!! In my opinion, just rebuild your 401!!
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Stuka
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Re: my 401 is TIRED... thinking about a swap

Post by Stuka »

Fast Eddie wrote:My J20 was a QuadraTrac and PO swapped out a NV4500 and Dana 300 T/C. Lots of work and $$$ but it IS a very nice combo to drive now! Axle in rear needs to be swapped for manual and of course a modified rear drive shaft. Just FYI!!! In my opinion, just rebuild your 401!!
Not to hijack, but there was only one rear axle used on J20's. Both manuals and autos had the same rear axle that was offset 3" to clear the fuel tank. No need to swap that out unless you are also changing the tank.
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Fast Eddie
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Re: my 401 is TIRED... thinking about a swap

Post by Fast Eddie »

No Problem, looked at my notes from PO, he swapped out the axle to get the Limited slip, not to change axle center location, my mistake!! (Still learning about this vehicle)! THANKS
1979 J20, 360 w/NV4500/D300 Twin Stick/3.73 SOLD
1978 Cherokee Chief W/T Levi interior, 360 Q/T. SCRAPPED
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will e
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Re: my 401 is TIRED... thinking about a swap

Post by will e »

A swap is pretty expensive, especially all of the add ons. If you were daily driving it I would say 'go for it'. It you put just a few thousand miles a year on it I would stick with the 401 and have it rebuilt and spend the money on other upgrade options.
This after doing a compression test. If you have good compression and good oil pressure then figure out why it's not runnng as good as you expect. Keep in mind, none of these rigs are rocket ships.
Are the fouled plus next to each other? It would indicate a blown head gasket or a warped head if they are.
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Re: my 401 is TIRED... thinking about a swap

Post by Stuka »

And also, are they still fouled after replacing them with new ones and driving for a while?
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mgbreis
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Re: my 401 is TIRED... thinking about a swap

Post by mgbreis »

I appreciate the pointers on maybe getting the 401 running a little better. I have a vacuum gauge and will try to tune the carb little this weekend. BTW, is it weird that it is a 401 and it has a Motorcraft 2 barrel? It all looks original. The fouled plugs are not next to each other, one on each side. And yes, I did put new plugs in when I was reviving it. I forgot to mention oil pressure, it's not great. I've been running 30w in it and it's under 20lbs when hot. I'm actually not too concerned about mileage, but would enjoy overdrive just for the more relaxed highway manners. I know that's not what most of the members here think about!
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Re: my 401 is TIRED... thinking about a swap

Post by tgreese »

Year/model/tag number/VIN?

AFAIK the only 401s with 2Vs were used by IHC in some pickups or Travelalls. Jeep only offered the 401 1974-78, and only with the Motorcraft 4V carburetor. The 360 was offered with a 2V or a 4V, but not the 401.

20 lbs hot idle is not bad ... not like a new engine, but not about to self-destruct. These engines will show very low hot idle oil pressure when worn out, like 5 psi or less. The main danger at those very low pressures is to the rod bearings.

If you have trouble keeping the plugs clean, go to a stage or two hotter plug, or install anti-foulers.

15W40 Rotella (what I put in my Jeeps) or Delo would be good. No reason to run single viscosity in these engines. If the weather is really cold where you are, you could run a 10W30 or 10W40.

Should be fine on the highway if you have quiet tires and factory exhaust. Insulate the floor to make it quieter.
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mgbreis
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Re: my 401 is TIRED... thinking about a swap

Post by mgbreis »

It's a 78 Wagoneer, or at least that's what the title says. I have confirmed the "401" cast on the side of the block. The oil pressure fluctuates a lot, which probably isn't unusual. But it drops pretty low when running steadily at higher rpm. I actually am running the 15w40 rotella, my recollection on the 30w was wrong. I should change the oil again anyway. When I got it the old filter had about a half inch of grease on the top side and the old oil came out in globs. I'll post a few pics of the tags etc. Sorry if you can't read any of it, it was dark and cold!
ImageImageImageImageImage


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Re: my 401 is TIRED... thinking about a swap

Post by tgreese »

There should be a tag on the right-hand valve cover that will tell you the engine build date.

The 3DA2 carburetor is a 2100 from 1973ish with an automatic, I'd guess from a Commando with a 304 V8. Could also be from a 1973ish Wagoneer, also with an automatic, but the DA number seems to be associated with the 304, and there was no 304 in a '73 Wagoneer or J-truck. And 1.08" venturi is the smallest of the Motorcraft 2100 2Vs, though that does not rule out an original 360 application. The 304s all got 1.08".

It's way wrong for a 1978 tag, which would be something like 8DA2 for a 304 automatic in 1978. Additionally, Jeeps were getting 2150s by 1978, not 2100s.

VIN is right. Jeep, 1978, Automatic, model 15 (Wagoneer), N = 6200 GVWR, Z = 401 4V, sequential serial number. 7L is Loden Green paint, 1BR is Black Brampton Plaid Cloth trim. The rest of the VIN plate is expalined in the TSM, but only makes sense to Jeep Corp.

The OP gauge should not jump around. I would look at the connection to the sender (next to the oil filter) and test the gauge using the procedure in the TSM. Jeep calls for a special tester, but you can use fixed resistors and a couple of clip leads instead. The sending unit is a common failure. A quality aftermarket mechanical oil gauge will tell you more.

A good rule of thumb is you need at least 10 psi for every 1000 RPM. OP should hold steady at cruise around say 30 or 40 psi. OP at hot idle should be your lowest reading, and rise steadily with engine speed to whatever it is at cruise. Any other trend - suspect the gauge.
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Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
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Stuka
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Re: my 401 is TIRED... thinking about a swap

Post by Stuka »

So the question is, why did somebody swap out the intake? I don't see any signs of an adapter. And like tgreese said, that carb is way small for a 401. That could make it run very lean if its still jetted for a 304, and it just kills mid-top end power.
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mgbreis
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Re: my 401 is TIRED... thinking about a swap

Post by mgbreis »

The engine code tag says 109Z09. Assuming its the original engine I'm assuming an owner in the distant past must've swapped out the intake and carb seeking better mileage?

I really appreciate the information, I didn't even know that tag on the valve cover existed!
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Re: my 401 is TIRED... thinking about a swap

Post by Cecil14 »

Honestly it could've been swapped for a number of reasons; mileage may have been one, but I've seen people swap stuff for far worse reasons. ie: the original carb didn't work right, I didn't know how to fix it, and I happened to have this fancy setup from a running 304 that bolted right on. It's easier to swap intakes to some people than just fix what's there. People are crazy. :)

I always assume the worst when looking at new problems, and just plan out the *correct* fix.

I'm with everyone else so far, do your standard troubleshooting and see exactly where you're at with the 401. I think you've likely got a pretty healthy motor under all the surface problems.


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Re: my 401 is TIRED... thinking about a swap

Post by babywag »

If bought in CA a 2bbl intake could be stock, for last couple production years only 2bbl was offered.
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Re: my 401 is TIRED... thinking about a swap

Post by tgreese »

mgbreis wrote:The engine code tag says 109Z09. Assuming its the original engine I'm assuming an owner in the distant past must've swapped out the intake and carb seeking better mileage?

I really appreciate the information, I didn't even know that tag on the valve cover existed!
1 = 1977
09 = September
Z = 401
09 = 9th day

Reasonable build date for a 1978 model. Again, your TSM will have this info.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
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Re: my 401 is TIRED... thinking about a swap

Post by fulsizjeep »

Stuka wrote:So the question is, why did somebody swap out the intake? I don't see any signs of an adapter. And like tgreese said, that carb is way small for a 401. That could make it run very lean if its still jetted for a 304, and it just kills mid-top end power.
This 401 would have had the 4350 spread bore. If that got to be difficult to keep running, a reasonably cheap swap would be to a 2bbl set up. I kept the 4350 going fairly strong in wife's 77 401 until 2010 and just got tired of dinking around with a worn out carb. Most the 4350 still in use are probably pretty worn by now unless it is very low miles. I think it is not really "way small" for a 401 but more like "a little small". The last 401 I pulled had a 2100 and 2 bbl intake on it and it ran pretty damn good.
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Re: my 401 is TIRED... thinking about a swap

Post by fulsizjeep »

babywag wrote:If bought in CA a 2bbl intake could be stock, for last couple production years only 2bbl was offered.
Weren't they painted red also?
Flint Boardman
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