my 401 is TIRED... thinking about a swap

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

Post by babywag »

fulsizjeep wrote:
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?
Nope, but I believe for ‘78 if you wanted a 401 in CA it was a 2bbl.
IH 401 was also 2bbl & I believe a 2100 carb.

I went look @ j10 down road many years back it was original owner. It was a 2bbl 401, Unmolested all original, old dude wanted way too much for it.
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fulsizjeep
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Re: my 401 is TIRED... thinking about a swap

Post by fulsizjeep »

babywag wrote:Nope, but I believe for ‘78 if you wanted a 401 in CA it was a 2bbl.
IH 401 was also 2bbl & I believe a 2100 carb.
That's right, it's the IH 401 that was red.
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tgreese
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Re: my 401 is TIRED... thinking about a swap

Post by tgreese »

fulsizjeep wrote:
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?
304s and 360s were red in California in 1972 and I believe 1971 too. 1973 they all were metallic blue.

I find no evidence of any factory 2V with a 401 in any of the years 1974-1978. They are all Z code, and that is explicitly given as a 401 4V in years 75-78. The Z code is gone in '79. Jeep distinguishes the 360 2V and 4V with a different VIN engine code, N and P resp. There is only one code for 401, Z.

In the carburetor listings, there is no listing for a 2V 401 in any of the years where the 401 was offered. There are a few different 4V carbs for 401s depending on the year, including a 4THD4 for the '74 J20s with manual transmission, and a 6THA4C for the '76-78 California cars (I presume these are all 4350s). But no 2V and 401, California or not.
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Re: my 401 is TIRED... thinking about a swap

Post by babywag »

Well you can believe it or not, but they exist for 1978. I have seen ‘em, there is also rumors of Canadian and export 2bbl/401 engines.
-Tony
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will e
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Re: my 401 is TIRED... thinking about a swap

Post by will e »

BTW, the tiredness might just be it isn't getting enough air. ;) Once you check the compression and such swap a 4bbl onto that bad boy.

Have you confirmed it is a 401 on the block?
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Re: my 401 is TIRED... thinking about a swap

Post by fulsizjeep »

I met a California Wagoneer once some 12-14 years ago. I want to say it was a 77 or 78 Z code. It was for sale. Talked to the owner a bit. He bought it from the first owner who said the 401 came with the 2bbl set up. Yeah, I checked the engine casting. There was a decal under the hood that also indicated it was equipped with California emissions and 2bbl carb. He wanted way too much for it considering one of the rear quarter panels had been smashed and beat back out with a hammer. Otherwise, it was a decent Wag with 2" AAL w/30" tires. Next time I went by there it was gone and I haven't seen it since.
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Re: my 401 is TIRED... thinking about a swap

Post by letank »

as usual back to basics: diagnostics to find the problems(s) starting with the easiest: timing (at least 12, but 14 is better and add for elevation), spark plugs, then to compression and carburator rebuilt especially if you are smelling gas we can suspect blown power valve.
Years ago I went to test a rebuilt 401 with a documented list of over $6K, it was a dog, no pick up power, worst than my 74 with 2.72 gearing and 1.08 venturi 2100. Which may also be a point to check that your carb is the 1.21 venturi version -stamped on the driver's side behind the solenoid
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mgbreis
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Re: my 401 is TIRED... thinking about a swap

Post by mgbreis »

I spent some time with it yesterday, checked the plugs and actually that issue seems to have cleared up because they all looked good. Dry and tan. I know this sat for years and was very neglected/beaten, so maybe the two oil changes and new plugs helped. Although, I swear when I got it and took the plugs out two of them looked like they'd been dipped in old wheel bearing grease. I didn't check the compression because I don't have time right at the moment. Too many Christmas chores.

I set the carb with a vacuum gauge, about 16hg at idle so that seems good. I also found two vacuum leaks where the ends of the hoses had split. So that should help. I think its the 1.08 carb, I saw that on the side yesterday. I'm not doing a manifold/carb swap, that would be like waxing the deck on the Titanic as its going down! It'll stay as is for now, I still want to fix the rust and plan for either an efi swap or an engine swap. I have other projects so nothing too drastic at the moment!
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tgreese
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Re: my 401 is TIRED... thinking about a swap

Post by tgreese »

Pretty sure if a 1978 401 got a 2V, it would be a 1.21" 2150. This is clearly a 1.08" 2100 - you can see the carburetor model and the venturi size in the pics above.

I'm just surprised that Jeep would not document such 2V vehicles. I could only imagine that they ran into some homologation problems with California at the end of 1978, and dealt with it that way. And then, why would they not document it in the parts book? Strange. Maybe there is a service bulletin that applies?

Or maybe it's an end-of-run issue? Both the P and Z codes are gone for 1979, so the 4350s were eliminated around then.

Back to the OP, if you have not rebuilt the carburetor, that would be a good move. Get a kit for a 1973 CJ-5 with a 304, and it should fit. Almost any carbureted car that's been sitting idle need to have the carburetor gone through. The kit would come with a new power valve.

If you needed to fix vacuum lines, I'd suggest replacing all of them. The TSM will show you how they are connected, and almost all of them are 5/32" ID that you can readily get at the parts store.
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Re: my 401 is TIRED... thinking about a swap

Post by letank »

Looking good. Also when the transmission modulator goes on the TH400, the engine will suck large amount of transmission fluid at idle and the exhaust will let go a large puff of white smoke...

Before I fixed the valve seals, and it passed smog.

Image

and the 1.08 venturi, it took me year to figure out why I was getting such a good mileage until

Image

Hope they post
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Re: my 401 is TIRED... thinking about a swap

Post by Stuka »

fulsizjeep wrote:
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.
Oh, it can run good. It just really limits power. And it would need to be re-jetted to not be really lean if it was a carb jetted for a 304.
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Re: my 401 is TIRED... thinking about a swap

Post by fulsizjeep »

This is true Brandon. The 360/401s are surely set up for better power when they can breath. I sometimes still miss the days of a my reliable 2150 aspirated 360 for all around use. I was kind of amazed at how well it worked for off-road steep incline/decline/off camber/bumpy driving.
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Re: my 401 is TIRED... thinking about a swap

Post by Nikkormat »

The intake runners aren't much different from the 2bbl to the 4bbl spreadbore intake. I say after a compression check you ought to pick up a 500cfm Holley 2bbl and try tuning it up a little.
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Re: my 401 is TIRED... thinking about a swap

Post by fulsizjeep »

I know a few people who went this direction. I think the best new 2bbl for the stock engine w/2bbl intake is the Holley 500.
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Re: my 401 is TIRED... thinking about a swap

Post by HeavyMetalThunder_81 »

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

Post by REDONE »

Dizzle! That's so shiny!
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Re: my 401 is TIRED... thinking about a swap

Post by fulsizjeep »

It looks like some kind of fishing lure to me. I dunno...
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REDONE
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Re: my 401 is TIRED... thinking about a swap

Post by REDONE »

Haha! Maybe bait, but it's cheaper than the 4bbl fuel injection I put on money badger, and it's Holley! Now I'm thinking about Hot Wheels with the stock 2bbl and 360...
79 J-10 (Honcho Mucho) KE0LSU
304/Performance Fuel Injection TBI/MTA1/SP2P/Magnum rockers
T18/D20/D44s&4.10s/33" Mud Claws
Grizzly Locker Rear
4" front spring drop, 5" rear shackle flip
Chevy style HEI (ECM controlled)
Dolphin "Shark" gauges in a fancy homemade oak bezel
3/4 resto, rotting faster than I've been fixing it.
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Re: my 401 is TIRED... thinking about a swap

Post by tgreese »

JMO - I have used the 500 CFM 2300 Holley on a Jeep, and while it gives a significant power boost over a 2100 on the street, it's a terrible carburetor on the trail. It floods and starves badly over bouncy terrain, and there are uphill and downhill attitudes where it won't run without pumping the pedal. Look in the 4WD literature and you will find many articles about improving the Holleys with spring loaded floats, slosh baffles, improved bowl vents, etc. This is in addition the conventional tuning you'd need for a custom application ... jets, shot cam, power valve, and so forth.

There are new 2150s available from this eBay seller https://www.ebay.com/itm/NEW-MotorCraft ... ccATR7gYzA and he could likely build a 1.21" 2150 that would work well without much tuning on the 401. These carburetors are much much better on the trail than the 2300, and considerably less expensive.

If you want to use a Holley, buy a book about tuning them. They are pretty easy to tune, and the tune-up parts are widely available. If you go with all the off-road mods, expect to pay more than $100 extra for tuning parts and modifications.
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
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Re: my 401 is TIRED... thinking about a swap

Post by fulsizjeep »

Wow. This is good news Tim. Thanks!
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