B Revs High on it's own
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=194317
Printed Date: 11 Nov 2024 at 9:39pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: B Revs High on it's own
Posted By: BenGiBoy
Subject: B Revs High on it's own
Date Posted: 29 Mar 2023 at 7:32pm
So... Long story short, my B had to sit outside for a few months (supposed to be two weeks max, but that's a long story) and I wasn't around to start it periodically. When I got back to it there was 2 gallons of water in the oil which ran down the muffler and in through the exhaust valves which also seized the engine up. I pulled the head and got it un-stuck, pulled the oil pan and cleaned all the gunk out, as well as visual inspection of all components... (77 Hours on the new rebuild...  ) Everything looked okay from the bottom, so I put that all back together and started it... It started right up and idled for a minute, but then revved up really high and I couldn't control anything with the throttle, the governor is holding the throttle on the carb as far closed as it can, so it's not something on the governor. I thought maybe it was something gunked up in the carb causing weird over-fueling or something so I took that apart, cleaned it, and re-installed with fresh fuel and a clean sediment bowl/screen. It seems to have the same problem still.... Any tips? I did drive it a little with it revved up to see if it would change anything and it didn't, but I did notice that it had no power at all, if that helps with anything. As I type I realized I should probably go check the valve lash... but would that do it? Thanks for any help! This is getting frustrating... Ben ------------- '39 Model B Tractors are cheaper than girls, remember that! |
Replies:
Posted By: steve(ill)
Date Posted: 29 Mar 2023 at 8:30pm
|
if it revs up , you got too much fuel... Someone else had this problem a month ago and found the throttle arm on the carb was stuck on one of the mounting bolts and would not move to LO IDLE postion.. To set the governor and carb. pull off the pin connection on the carb rod that goes forward and pins to the governor arm that runs behind the radiator, from gov to left side..... put the THROTTLE lever on the steering column to WIDE OPEN... move the gov arm and spring back and forth to see that it moves... Go to the left side of the tractor... pull the carb rod forward and back and see that it moves all the way forward, and goes back against the idle stop..... now pull the carb rod all the way FORWARD and see if the pin aligns with the governor arm behind the radiator... If not, bend the gov arm a little bit so they align..... reinstall the carb rod to the governor arm.... retest. ------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 29 Mar 2023 at 8:34pm
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tractor really can not REV UP unless the throttle plate in the carburetor is OPEN... You shut down the air, and the engine speed drops...no air flow, no fuel flow ( suction). ------------- Like them all, but love the "B"s. |
Posted By: TramwayGuy
Date Posted: 29 Mar 2023 at 9:03pm
| The throttle plate is probably stuck somewhere above idle. It can’t slow down any, and it can’t open up when a load is applied. |
Posted By: BenGiBoy
Date Posted: 30 Mar 2023 at 4:30pm
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I'll check it out and see what I come up with, thanks for the suggestions! ------------- '39 Model B Tractors are cheaper than girls, remember that! |
Posted By: Steve in NJ
Date Posted: 30 Mar 2023 at 5:59pm
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Sounds like all the rain or snow got the throttle shaft rusty. Might need a little penetrating oil on the throttle shaft...... Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: BenGiBoy
Date Posted: 30 Mar 2023 at 7:10pm
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I will try lubricating that a bit and see what happens, thanks! ------------- '39 Model B Tractors are cheaper than girls, remember that! |
Posted By: BenGiBoy
Date Posted: 10 Apr 2023 at 7:50pm
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Well, I finally got some time this weekend to look at it... I found that I needed to adjust the governor rod some, it was 1/4"or so out of wack... But that didn't help. The throttle rod in the carburetor is as free as it can get, opens and closes easily. The tractor is still idling really high even with the throttle plate as closed as it can get. It seemed to go faster and faster if I tightened the idle jet screw on the carburetor though, do I just have the carburetor way out of whack? What do you guys usually set yours at? (It has the Zenith carb). Thanks! Ben ------------- '39 Model B Tractors are cheaper than girls, remember that! |
Posted By: steve(ill)
Date Posted: 10 Apr 2023 at 8:37pm
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adjust the spring loaded screws out 1.5 turns , after you screw them in to bottom... Again, the engine can not REV UP if you have no air flow... Make sure the throttle lever goes all the way CLOSED. ------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 10 Apr 2023 at 8:40pm
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faster and faster if I tightened the idle jet screw on the carburetor though are you adjusting the JET SCREW or are you adjusting the THROTTLE STOP ( idle point).. that screw increases speed as you screw it in and open the throttle lever. ------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 10 Apr 2023 at 8:46pm
I dont know what carb you have... but "generically"... the circle on the left is the mixture screw ( to set full throttle / good running)... and the circle on the RIGHT has a screw that pushs on the throttle rod and OPENS the plate to increase idle speed.... The CHOKE is the bottom plate. ------------- Like them all, but love the "B"s. |
Posted By: BenGiBoy
Date Posted: 11 Apr 2023 at 7:49am
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I'm confused as well...I've gotta have something going on. I'll try and get some pictures and maybe a video if I can get that to work on here. I was adjusting the jet screw, the idle stop screw that would hold the throttle plate open is backed off so it doesn't touch the stop at all. Ben ------------- '39 Model B Tractors are cheaper than girls, remember that! |
Posted By: SteveM C/IL
Date Posted: 11 Apr 2023 at 9:18am
| Remove carb and see what the butterfly is doing. With screw backed off it should close enough to kill engine |
Posted By: Tbone95
Date Posted: 11 Apr 2023 at 10:32am
| Have you got a crack or bad gasket somewhere that's sucking air? |
Posted By: steve(ill)
Date Posted: 11 Apr 2023 at 12:35pm
|
the air just about has to come thru the throttle plate.. If not, it will not PULL gasoline with it... and therefor not REV up. ------------- Like them all, but love the "B"s. |
Posted By: youngorange2000
Date Posted: 11 Apr 2023 at 8:31pm
| I had a C that would surge until I added a mising 'surge spring' from the carb to the block drain and the problem went away. I think they still sell them but they were like $40 I just made my own out of a spring I had and some wire |
Posted By: DrAllis
Date Posted: 11 Apr 2023 at 9:57pm
| REMOVE THE CARB AND MAKE SURE BOTH SCREWS ARE IN THE THROTTLE PLATE AND IT IS CENTERED AND IT CAN FULLY CLOSE !!! A fully closed throttle plate the engine CANNOT run !! |
Posted By: BenGiBoy
Date Posted: 25 Feb 2024 at 7:13am
|
I got busy and didn't have a chance to look at it for a while but last weekend I decided I'd look at it and it was either going to get fixed or I'd have to get someone else to look at it if I couldn't figure it out. First step - pull carb and go through the list of suggestions that everyone left for me and I decided instead of fussing with getting the carb out with the air cleaner on I would pull the air cleaner. Low and behold I should have pulled that a long time ago. The little chamber that the air flows through after the air cleaner and where the carburetor goes too was full of gasoline... Must be someone didn't have the fuel shutoff turned off when they parked it.... Oops! Anyhow, I tried running it without the air cleaner on and it ran like it was supposed too, and with it back on it still works correctly!! I guess I should have taken that off the first time I pulled the carb... Sigh. Anyhow, I figured that ya'll might like to hear what I found! I guess that must be the air coming through the air cleaner must have had enough fuel in it that it didn't really have to mess with anything in the carb? I'm not really sure how it still was running at such a high idle, but I guess that I don't totally care as long as it's fixed... Thanks for all the tips! Ben ------------- '39 Model B Tractors are cheaper than girls, remember that! |
Posted By: resurrection20
Date Posted: 29 Feb 2024 at 10:46pm
| This saga was a 10 ticket thrill ride! I had a carb that would flood that exact passage due to an improper float position. But the tractor just backfired. |