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Unread 04-01-2014, 10:56 PM   #1
Registered User
1979 CJ7 
Join Date: Mar 2014
Location: Jackson, Idaho
Posts: 25
A little more help with my carburetor?

So my 79 cj7 has a square bore manifold, I believe it is cast not aluminum, I don't know what it is off of... it has G.P.2.-P. AMC cast on it in front of the carb. mount. The carb is a Motorcraft 4350 4bbl. which is a spread bore on an adapter. I bought a rebuild kit for it and put it back on and it seems to have made my problem worse. Here is my problem, when I drive down hill, or on really uneven ground it throttles up. Before I worked on it, it was manageable with the brake. Now sometimes it throttles up and wont idle back down unless I shut it off and restart it. I'm ready to scrap it. I'm looking for any help with the 4350. this will be my main off-roader it will see very little pavement. Any suggestions on a better set up? By the way the timing is set at 5 deg. BTDC if that makes a difference.

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Unread 04-02-2014, 07:12 AM   #2
Mike Romain
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1986 CJ7 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 18,090
Bad engine or tranny mount allowing the gas pedal linkage to get too tight or pulling on the linkage cable. Have seen this before.

Have more often seen a mechanical choke linkage cable that doesn't have a lazy S bend in it do this. Choke cables have to have the S in them for engine movement.

Just a couple wild guesses for you...
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89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 04-02-2014, 07:56 AM   #3
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1981 CJ7 
Join Date: May 2011
Location: Elbert, CO
Posts: 15,643
I've read the 4350 was notorious for flooding on inclines, and leaning out on descents. Based on my research, it's generally considered a poor off-road carb.

You might consider a Holley, since you have a square-bore manifold.

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Unread 04-02-2014, 11:38 PM   #4
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1979 CJ7 
Join Date: Mar 2014
Location: Jackson, Idaho
Posts: 25
Motorcraft 4350 I think I have it figured out, I talked to a guy who used to do a lot of work on Ford carbs. I just had to get the float in the right position, and the vacuum piston fine tuned. There is a primary and auxiliary valve on the fuel inlet, so you really have to check the float levers and make sure its dialed in right to seat. I went with a **** hair over an inch on the float level, and 1/32 on the auxiliary inlet. I think my problem worsened when I dropped my transfer case for the lift. It was probably out of tune because the PO had already dropped the t case 1". The vacuum piston and metering rods are another story I guess you have to dial them in over time. I found a link online that said 1/8" of travel that was 6 turns for me. I went 1.5 turns on the idle air mixture screws. 2 notches rich on the auto choke. Also on the primary throttle lever there was a tab that was bent and wasn't catching a spring end on the secondary shaft so the secondary throttle plates weren't being opened.
That little lever that was bent got caught on the wrong side of that spring and stuck the carb wide open on a test drive, which wouldn't have been bad If I could have had my brakes bled, I tried and tried after the lift, damn near wet myself, I came in hot about 20mph into the shop, luckily my dads project 46 power wagon was parked in there and I managed to hit my front tire on his and bounced it back about 5 feet, thank god it was there and weighs so much or the shop would be a drive thru. I think the 10 psi in my tires really helped out. When I got out the end of my handyman jack was about 2" from the side of his Coronet project. My jeep has a nasty sense of humor to do that to me last night, on April fools. Thanks for the replies guys.
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