"B" engine problem

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   Here' hoping some of you have some valid suggestions. I have B that has decided to not run properly. It went from an intermittent miss to almost not running at all. Why during hay season who knows. The tractor is a 1940 and has worked it's entire life. I do not know how many times it's been rebuilt. As it is now it will only run a full throttle with the choke almost closed. Here's what has been checked so for. The compression is 89 pounds or slightly better on all 4 cylinders. The fuel supply at the carb will run a full stream for as long as the shutoff is open. The carb has been rebuilt twice and also swapped for a different one from another tractor. The mag has been swapped 4 times with others. 3 mags rebuilt by me, one rebuilt by Steve at B&B. The exhaust/intake has been removed and a new gasket installed. Plugs have been changed several times. Any suggestions on where to go next ? It difficult to get haying done and be down a tractor but we are managing. 
  jim wiggin

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wigtrain Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 18 Jul 2010 Location: Maine Points: 66	Post Options Post Reply Quote wigtrain Report Post Thanks(0) Quote Reply Topic: "B" engine problem Posted: 10 Jul 2019 at 7:46am
	Here' hoping some of you have some valid suggestions. I have B that has decided to not run properly. It went from an intermittent miss to almost not running at all. Why during hay season who knows. The tractor is a 1940 and has worked it's entire life. I do not know how many times it's been rebuilt. As it is now it will only run a full throttle with the choke almost closed. Here's what has been checked so for. The compression is 89 pounds or slightly better on all 4 cylinders. The fuel supply at the carb will run a full stream for as long as the shutoff is open. The carb has been rebuilt twice and also swapped for a different one from another tractor. The mag has been swapped 4 times with others. 3 mags rebuilt by me, one rebuilt by Steve at B&B. The exhaust/intake has been removed and a new gasket installed. Plugs have been changed several times. Any suggestions on where to go next ? It difficult to get haying done and be down a tractor but we are managing. jim wiggin
	Jim Wiggin

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WF owner Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 May 2013 Location: Bombay NY Points: 4410	Post Options Post Reply Quote WF owner Report Post Thanks(0) Quote Reply Posted: 10 Jul 2019 at 7:58am
	I am betting that you have either an obstruction in the fuel system, possibly the inlet of the sediment bowl or a dirty carb.

Gerald J. Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Hamilton Co, IA Points: 5636	Post Options Post Reply Quote Gerald J. Report Post Thanks(0) Quote Reply Posted: 10 Jul 2019 at 9:45am
	The shop manual should be a help. http://geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf There are many things that have to be right for an engine to run as planned and any one of those things can be the cause of poor running. Gerald J. Edited by Gerald J. - 10 Jul 2019 at 9:46am

chaskaduo Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 26 Nov 2016 Location: Twin Cities Points: 5203	Post Options Post Reply Quote chaskaduo Report Post Thanks(0) Quote Reply Posted: 10 Jul 2019 at 10:13am
	Could a valve or two adjustments loosened up?
	1938 B, 79 Dynamark 11/36 6spd, 95 Weed-Eater 16hp, 2010 Bolens 14hp

Dick L Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Edon Ohio Points: 5082	Post Options Post Reply Quote Dick L Report Post Thanks(0) Quote Reply Posted: 10 Jul 2019 at 11:57am
	Do you have a different manifold to swap with the one on the tractor? If you have a full stream at the carburetor, have changed carburetors that have been rebuilt, installed a new manifold gasket and still need a lot of choke I would guess you have an internal manifold leak. Here is a picture of an manifold I sawed into sections to find an internal leak caused by a core shift when cast. Edited by Dick L - 10 Jul 2019 at 11:58am

wigtrain Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 18 Jul 2010 Location: Maine Points: 66	Post Options Post Reply Quote wigtrain Report Post Thanks(0) Quote Reply Posted: 11 Jul 2019 at 4:29pm
	Thanks for all of the help. Today I swapped out the manifold from one of my other B's that was running well. No change with the problem. At this point I'm so frustrated I may turn it into a parts tractor to help keep my others running. Maybe I'll feel better tomorrow
	Jim Wiggin

Dick L Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Edon Ohio Points: 5082	Post Options Post Reply Quote Dick L Report Post Thanks(0) Quote Reply Posted: 11 Jul 2019 at 7:03pm
	Never give up! Instead use it as a challenge that it will not stump you long. Having a full stream of gas at the carburetor and it being able to run wide open would mean you are getting gas thru the power jet it needs using the choke. Normally if you have an obstruction you would be able to run at idle and the obstruction would keep it from running wide open. You have proven that you do not have an air intake leak. You have proven you have fuel at the carburetor. You have proven you have compression. You have proven you have spark. How close have you proven it is in time? Have you proven the firing order is correct. 1243 This engine will run with two wires crossed up. Not well but will run. If it has the Zenith non adjustable carburetor the idle circuit might be plugged or not adjusted. an upside down gasket can plug that. Just some things to think about as you trace thru the details.

DougS Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 03 Nov 2011 Location: Iowa Points: 2490	Post Options Post Reply Quote DougS Report Post Thanks(0) Quote Reply Posted: 11 Jul 2019 at 7:15pm
	I would lean toward a clogged carb jet, since it slowly started to run worse. If the mag is a little loose, it could have gone out of time. Are you using new spark plugs? Just because the plugs look good doesn't mean they are.

Boss Man Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 03 Mar 2018 Location: Greenleaf, WI Points: 608	Post Options Post Reply Quote Boss Man Report Post Thanks(0) Quote Reply Posted: 11 Jul 2019 at 7:41pm
	Did you do the compression test with all the plugs out? When was the last time the plug wires were changed? Do you have copper core wires?

DaveKamp Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Apr 2010 Location: LeClaire, Ia Points: 5641	Post Options Post Reply Quote DaveKamp Report Post Thanks(0) Quote Reply Posted: 11 Jul 2019 at 10:52pm
	I'll second Boss's note... copper (not graphite) wires for a magneto... resistance wires will drive the magneto's voltage WAY TOO HIGH, and it'll internally short the magneto's coil. Start it up after dark, and look around each plug wire, and the magneto... do you see any 'fire' where there shouldn't be 'fire'?
	Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest.

festus51 Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 26 Mar 2017 Location: Osage City, KS Points: 1639	Post Options Post Reply Quote festus51 Report Post Thanks(0) Quote Reply Posted: 11 Jul 2019 at 10:59pm
	If it runs using the choke it sounds like not enough gas is getting through. I will go with a gas circuit being somewhat plugged up on the interns of the carb
	We the unwilling Led by the unqualified Doing the impossible for the Ungrateful

B26240 Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 21 Nov 2009 Location: mn Points: 3860	Post Options Post Reply Quote B26240 Report Post Thanks(0) Quote Reply Posted: 12 Jul 2019 at 6:07am
	Whatever you end up finding keep us posted as that is how we all learn. I had a Farmall H that had a wiered miss when Idling and would spit a little fire out the exhaust. It turned out to be a bad manifold.