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Post by fred46 on May 2, 2021 15:53:48 GMT -5
My rebuilt L4-134 is in a self restored ‘46 CJ2A (owned and under my care since ‘71). She chugs at idle only when warm. Chug, chug, chug.......idle speed good and holds adjustment, idle mixture when adjusted responds as normal and holds its setting. Cold idle all is good. She also pops and backfires when warm at moderate road speed when I back off throttle going downhill. Gold start great, warm/hot start is great. Running/driving at higher rpm is great. It never stalls, always dependable. Just the chugging at idle and popping going downhill when warm isn’t right. Carter WO (model tag missing) is from a ‘48 CJ2A. Carb was professionally rebuilt when I rebuilt the engine many years ago and has been through many years of winter storage and fair weather driving. So my first thought is it’s time for a carb cleaning/rebuild. (I’ve done YF carb rebuilds before, just not a WO). BUT reading Scoutpilots posts he recommends checking all other aspects before tearing into a carb which I understand. Those things should be good as I maintain and tune up regularly but I can’t tune out the chugging or the downhill popping. Anyone’s thoughts? The engine is long due for a valve adjustment so I am proceeding with that first. Carb is now off pending it’s likely rebuild, manifold removal, and valve adjustment. I picked up a Carter NOS master kit. And ready to go. I’m looking for any suggestions from my fellow experienced Willys fanatics on any other aspects needing attention before I tear into the carb. |
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Post by Scoutpilot on May 2, 2021 18:12:27 GMT -5
Need some numbers. Vacuum reading, Dwell, Idle RPM. Finish the valve adjustment and run a compression test. Then let's get those numbers.
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Lee
Full Professor
Vagabond Jeeper
Posts: 704
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Post by Lee on May 2, 2021 20:31:56 GMT -5
I would look at the distributor, sounds like your advance weights are flopping around due to loose or sloppy return springs, this is the most often overlooked part on a Jeep IMO.
Lee😉
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Lee
Full Professor
Vagabond Jeeper
Posts: 704
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Post by Lee on May 2, 2021 20:40:16 GMT -5
Oops
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Post by fred46 on May 4, 2021 23:13:17 GMT -5
Thanks for suggestions. I’m proceeding. i suspect carburetor or distributor shaft bushings/advance mechanism or valve lash. So today I removed carb, left front fender, manifolds to gain access to valve train. Will begin with adjusting valves then examine distributor You can see I removed the side cover to expose valve tapper adjustment. Will adjust tappet clearance to spec tomorrow.  Well, when I removed the intake/exhaust manifolds I found the likely problem... Cracked/broken ear on cylinder 1-2 intake flange. Look at the red circle on left, the tab below it was broken. 😕The one on the right is ok. 🙁 1/3 of the intake port for cylinders 1 & 2 was apparently leaking badly when warm. Vacuum was compromised. Very likely my problem. Can’t repair, will need a replacement intake manifold. 🙁  Here you can see better after I separated the intake from the exhaust. You can see the broken ear tab piece. I’m thinking the reason she ran okay when cold was the crack was closed. Once running and warmed up the manifold expanded and the crack opened more lowering manifold vacuum. Beginning my search for a replacement intake manifold. |
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Post by fred46 on May 4, 2021 23:14:59 GMT -5
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Post by Scoutpilot on May 5, 2021 2:18:32 GMT -5
Tough break. Good luck.
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Post by fred46 on May 19, 2021 10:39:37 GMT -5
Adjusted valves to .016, Completed replacement of broken intake manifold. Did NOT rebuild or disassemble WO carb, (followed Scoutpilots advice to check everything else first) so I just thourghly cleaned throat, ports into throat, blew it all off with compressed air. Installed and she fired right up. 👍
Followed Scoutpilots post on adjusting without timing light. Using dwell/tach, vacuum gauge.
Was able to get vacuum of 20.
She purrs like a 75 year old kitten. Next the test drive, shake down, spring cleaning. Just made it for the Spring Willys Reunion this Fri/Sat.
See you all there.
A BIG shoutout and thanks to ‘lowenough’ for the take-off period correct intake manifold.
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Lee
Full Professor
Vagabond Jeeper
Posts: 704
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Post by Lee on May 19, 2021 18:26:09 GMT -5
Nice!, enjoy it and have fun at the reunion....
Lee😂
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