Frustrating B
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=188807
Printed Date: 11 May 2024 at 2:47am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Frustrating B
Posted By: 10ptjim
Subject: Frustrating B
Date Posted: 10 Jun 2022 at 9:13pm
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have a B that starts and runs well, for awhile, after maybe 10 to 15 minutes of running and running at normal temp,it seems like the governor advances spark and starts to run rough to the point of killing the motor. gets noisey probably from detonation and losses power, leave it sit for a few and will start right back up without a hint it just died. want to go for a ride into town but am afraid to leave yard until this is figured out. Tank was replaced with real clean one and all lines cleaned, have tried at idle and faster rpm to see if it changes outcome and it does not, any ideas from the experts ?
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Replies:
Posted By: steve(ill)
Date Posted: 10 Jun 2022 at 9:18pm
my first thought would be a bad coil for the distributor, or in the mag... They get HOT and start to cut out... You should check the fuel flow to the carburetor and also that the gas tank cap is vented... But off when hot, then starts back up a few minutes later... a lot of times is the coil ( or condenser).
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Like them all, but love the "B"s.
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Posted By: 10ptjim
Date Posted: 10 Jun 2022 at 10:21pm
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will replace coil and condenser, so close to enjoying this thing,
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Posted By: WF owner
Date Posted: 11 Jun 2022 at 5:44am
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Before you replace anything, remove the gas line at the carburetor and drain gas into a container for a few minutes. Check to see if flow slows down after a few minutes.
If fuel flow stays constant, I agree with Steve that it's probably a coil problem and maybe condensor.
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Posted By: AaronSEIA
Date Posted: 11 Jun 2022 at 6:07am
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10-15 minutes usually isn't a long enough time for them to get hot. Do you have a mag or distributor? 12 or 6v? If 12v and a dist, do you have a resisted coil, or a resistor block? Technically, the governor has nothing to do with ignition. There is a mechanical advance in a dist, but that won't move on it's own unless the springs in it are broke. AaronSEIA
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Posted By: DaveKamp
Date Posted: 11 Jun 2022 at 7:00am
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You may also have detonation occurring due to something other than timing... spark plug electrode overheating can cause that kind of wierdness- the engine is cool, but the plug tip is not transferring heat to the head, so temp continues to rise until it becomes a glow-plug.
Usually this is the result of a poor crimp in the plug collar (threaded part) retaining the ceramic center, but an improper heat range can do it too. Usually, this occurs with Champion plugs (don't ask how I know...) and you will usually be able to SEE a combustion leak by looking at the plug after spraying some penetrating lube on the bottom insulator crimp-area and watching for bubbles at the insulator/collar joint.
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Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest.
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Posted By: 10ptjim
Date Posted: 11 Jun 2022 at 8:37am
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it is a mag 6v system, so maybe change plugs as an option also?choice of plugs?
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Posted By: steve(ill)
Date Posted: 11 Jun 2022 at 8:43am
when it stops running, get a spare plug and connect to one of the plug wires and have somebody crank while you look for spark...... that will help prove the coil / condenser theory.
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Like them all, but love the "B"s.
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Posted By: juniorp53
Date Posted: 11 Jun 2022 at 9:36am
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Autolite 295 is the plug of choice ...another quick check when it goes into one of its fits and dies give it a taste of starting fluid if it wont pop off you dont have spark
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Posted By: Northern Hoser
Date Posted: 12 Jun 2022 at 6:01pm
I second the fuel flow issue, 9/10 times I've seen this it's a flow issue. Other than the tank itself it can be partial blockages within the sediment bowl, usually at the inlet right above the shut off valve
Can be the fuel line as well and/or the fitting at the carb.
Matt
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Posted By: mdm1
Date Posted: 12 Jun 2022 at 6:51pm
Try running it with the gas cap off. My B would run for a while then shut off like it ran out of gas. Cleaned the fuel bowl no change. Checked gas flow at the carb. Finally loosened the gas cap and it ran fine. Good luck and if you get it going be sure to tell us what you did!
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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Posted By: brkfldj
Date Posted: 12 Jun 2022 at 8:09pm
Please make your changes one step at a time. Otherwise you may fix your problem and still not know which variable was the solution.
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Democracy is two wolves and a lamb voting on what is for lunch. Liberty is a well-armed lamb contesting the vote. ——— Ben Franklin
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Posted By: Wispitfiremike
Date Posted: 12 Jun 2022 at 11:24pm
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Jim, is my brother and we are working on these so you will see posts from two of us on the same tractor from time to time. We put a different and better condition tank and bowl on it to see if it would increase fuel flow and any issues that may cause and it was much bettter than old tank and sediment bowl. We also have an extra carb we are going to try, to help eliminate the fuel possibility. After that we will put in the plugs I am ordering in the morning. Can a condenser cool down quick enough to restart? and stay cool enough to run or is it not temp related just a bad part somehow? Planning on ordering that also. Really curious as to what a governor senses to advance the spark? Vacume or RPM? And yes we will try them one at a time so we can try to give an update to you for your help. The intermittent part is not fun to deal with as I know you are all aware so if this can help the next guy so much the better. Thanks again for all your help.
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Posted By: AaronSEIA
Date Posted: 13 Jun 2022 at 5:49am
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Again, it's not the governor that has anything to do with spark. There is a mechanical advance in the mag. 10 minutes of run time isn't enough to get it hot enough to fail.
AaronSEIA
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Posted By: WF owner
Date Posted: 13 Jun 2022 at 7:12am
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I keep an old lawn tractor tank, sediment bowl and plastic line with filter for trying a different engine. I've bought tractors that I had to use the small tank to load/unload them.
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Posted By: steve(ill)
Date Posted: 13 Jun 2022 at 8:43am
Your governor has two big weights.. It works off RPM.. When the motor overspeeds, the weights fly out and push the carburetor linkage to a lower RPM to reduce the speed...Thats all it does... As mentioned, the governor does not effect the motor dieing after 15 minutes... The mag works by retarding the spark to start, then runs at a constant 30 degree advance...... A distributor has a retarded spark, then centrifigual weights work with the rpm to advance the spark as you speed up the motor... eventually to 30 degrees.
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Like them all, but love the "B"s.
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Posted By: John426
Date Posted: 14 Jun 2022 at 10:27am
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About the spark plug. THe corss reference for Autolite 295 is NGK B4 . I use NGK B4-H with a longer thread length . NGK B4 have thread length of 3/8" (9.5mm) instead of 1/2" (12.7 mm) for NGK B4-H. Do you think that a longer thread is better or worse the ignition?
And is it better with 2 ground electrode?
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Posted By: steve(ill)
Date Posted: 14 Jun 2022 at 11:59am
Autolite and NGK are both good plugs for the B motor.... I would prefer the direct cross reference.... but with the low compression / low HP motor like the B, i dont see that longer plug hurting anything ................. and that is not causing the " die when hot" problem.
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Like them all, but love the "B"s.
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Posted By: ac fleet
Date Posted: 14 Jun 2022 at 12:28pm
got a C doing the same thing and now it wont even fire! --- got spark at points and all kinds of juice down there but cant get it to the plugs. tried 3 different cap and wire units and still no go!
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http://machinebuildersnetwork.com/
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Posted By: juniorp53
Date Posted: 14 Jun 2022 at 7:38pm
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AC fleet ... high side of your coil has an open ...your coil is junk
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Posted By: rw
Date Posted: 14 Jun 2022 at 9:34pm
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My biggest/longest fight with a gas tractor was caused by the rubber tip of the needle valve in the carb. The tip would swell when it was warm and lean out the mixture and created all the misfires and detonation you get with a lean mixture. Carb had not been apart for eons so I suspect ethanol in the gas on a rubber needle tip made for gasoline only. Eventually it it would die and not restart. It was swelled up like a sore thumb. Replaced needle valve and problem solved. Most of the time we only ran this tractor for a short period at low power and it was fine, but when you ran it 30 or 45 minutes working harder it would fail. Generally you could limp back to the barn and it was fine the next day. had plenty of flow to the carb, just not getting in there. Been a long time but I think I took the drain plug out of the fuel bowl on the carb to prove there was no gas in the carb.
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Posted By: corbinstein
Date Posted: 16 Jun 2022 at 6:27am
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I would try the Lawnmower gas trick first..... if it runs an hour on that, you know what time it is.
I had the same issue, and ended up drilling the top of the sediment bowl and putting a helf inch tall copper "stand pipe" on top of it with a couple holes drilled in the side. The stand pipe raised the fuel intake above the bottom by about half and inch. solved my problem, which was rust on the bottom plugging everything up.
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Posted By: 10ptjim
Date Posted: 20 Jun 2022 at 9:13pm
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Ok, update time, tank was changed, no change. changed the plugs, plug above oil filter turned out by hand,HMMMMM. no change, . Got condenser in mail ,installed and has run for 1 and a half hours with no problems. Condenser maybe the culprit. Thanks to everyone for the list of options to pin this down, i think a long ride is in order.Making lots of headway on these 2 B's we have thanks to this forum
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Posted By: mdm1
Date Posted: 21 Jun 2022 at 5:37am
Hey good to hear you got it going. Thanks for letting us know what you did.
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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Posted By: corbinstein
Date Posted: 21 Jun 2022 at 6:10am
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While you're at it, get a spare condensor and test to make sure it's good and put it up. The new condensors have a tendency to be junk right out the box.
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Posted By: 10ptjim
Date Posted: 21 Jun 2022 at 9:10pm
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a spare will be ordered, cheap fix and could save another headache, Thanks again all.
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