My Willys 3A and 3B Community
TECH FAQ SECTIONS => Engine compartment => Topic started by: DavidB on May 19, 2018, 08:45:24 PM
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Just rebuilt my carburetor, and cannot keep engine running unless choke is fully closed. I have correct pump travel and have set metering rod adjustment with the correct tool. I've also tried the propane torch , checking for leaks, but that didn't help or change performance...Iam at a loss. Any ideas out there? I appreciate any and all advice.
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If you have to run with it choked, you might have a vacuum leak or the Carter might have some debris caught in a jet.
Vacuum leaks can happen around the throttle shaft, the base of the Carter, and even at the intake manifold where it's bolted to the engine.
Is there a difference in performance when idling or at high speed? If so, this might help troubleshoot what might be clogged up.
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Yes, there is a difference between idling and increased throttle. It runs better with increased throttle, but the choke still must be fully closed.I had checked for vacuum leaks using the propane method I had read online about, but didn't notice any change.
Thanks for your input, I do appreciate it.
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I have found that if an engine must have the choke on to run, It needs a valve job.
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Think about this in the most simple terms. A carburetor is creating an air and fuel mixture that is optimal to be burned by the spark at the plug in the compression chamber.
If you are forced to cut off the amount of air, (choke) ...then there is already too much air mixing in the chamber. Thus why folks suggest trying to find a source where extra air is sneaking in.
Or, the amount of air is fine, but there is not enough fuel to reach the optimum fuel/air mix. A possible clog in the fuel delivery system. This can happen at the tank. The fuel pump and fuel lines...or in the carburetor itself.
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Athawk11,
I have confirmed that I am getting plenty of fuel up to the carburetor, so, I want to believe that my problem is within the carburetor itself. It seems like I am getting plenty of fuel down the carburetor when I actuate the throttle linkage, as I see a good stream of gas when doing this. So, which jet(s) should I check for obstructions?
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When was the last valve job? The engine must make enough suction to get the fuel into the cylinder. Leaky valves stop the suction.
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I do agree that an engine needs decent compression and vacuum to run well.
I'm simply looking at different issues based on past experience with the L-134 engine. With only marginal compression (70s) and low vacuum (15 at 5,500' altitude), I have been able to get them to idle and run with zero choke.
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Dave, I would probably start with the idle jet. It's the long skinny one. These are prone to clogs if the fuel supply isn't clean and filtered. I've had to clean one out on the trail a couple years ago.
Also, there is an overlooked passage way between the idle mixture screw port and the chamber behind the large plug on the front of the carb base. This can clog too, and is difficult to clean if the plug isn't removed. It can cause problems with carburetor function.
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Does the jeep have vacuum wipers or any other vacuum operated device? Check the supply tube(s) for proper fitment and/or any breaks.
Have you checked vacuum readings? What is your best idle RPM? If 900 and above, you may not notice a change in the motor with a volatile test, especially at altitude.
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Ok, here's the update..I have rechecked every jet, all were clear. I even changed bases, but it still doesn't run unless the choke is near fully closed. Does anyone have a well , clear picture of all phases of the rebuild on the carburetor? The ones I have are too grainy to make sure I have everything as it should be. I am also going to do a compression test. What numbers are acceptable on this ? I am almost ready to order a new Solex carburetor, but I want to keep it stock, if possible..if I had hair, I'd pull it out.
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Dave,
ScoutPilot is our resident expert, rebuilder, restorer of the Carter-WOs along with other models. He is more than happy to help you work through this by yourself, or rebuild it for you. Exceptional work, and a pure business professional.
His web site is packed with detailed photos and videos. If you don't find what you need, just post a question or send him a private message.
http://oldjeepcarbs.freeforums.net
He can be found on every Willys site too.
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Thanks so much for that . I will check it out.
I finally found time to pull a compression test..#1 -120lbs, #2=115lbs, #3- 120 lbs, #4--0--. So now I will remove the side cover and see if it's a stuck valve I suppose...I sure hope that is all it is, I am guessing that this is the answer to my carburetor woes?
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Ooooh. Most surely a problem. --0--? Sure sounds like a stuck valve. I was able to free up a stuck valve without pulling the head. Mix up some Acetone and ATF 50:50. Pull the side cover and the #4 plug. Squirt some through the spark hole and wait. Squirt and wait. Squirt and wait. Use a rod to gently push down on the valve. Use a paint scraper, knife. Work it between the tappet and bottom of valve stem. Keep working it back and forth this way. Keep squirting the above mixture. Eventually, the valve will be free.
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If the valve was stuck the rattle would be loud. Time to lap your valves and hope you don't need to grind them.
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Got the Valve freed up!!! I used Aerokroil and your advice on slowly working it up & down. Did not have to remove the head.It has good compression now, I will be buttoning it all back up & seeing how it runs soon.. I'm very appreciative for all the advice.
I will let you guys know how it turns out.
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Awesome!!
Hope it runs like a Swiss Watch!
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Well, it definitely runs much better, but still dependent on 3/4 choke..I think that it's time to waive the white flag and see if I can get someone to look at the carburetor for me.
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When was the carb last rebuilt?
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About 2 weeks ago, I did it myself, which I am beginning to regret. When I purchased this Jeep, it had a YF on it, and wasn't running well at all. I changed the intake and rebuilt the WO, and although it runs alot better now, it's still not right. I've checked about all I know to for now. The throttle body shaft doesn't seem too worn, wish I had a good known carb to rule out other issues.
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The throttle and shaft wear into egg shapes. Wear to the shaft and bores of the throttle flange in excess of .005" is a vacuum leak. If you want to check it yourself, take care to sheer the split or peened threaded ends before you break the top of the screws off trying to remove them. Call me with questions 336-963-3605.