Problems with H3 carb
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=192082
Printed Date: 23 Nov 2024 at 11:23pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Problems with H3 carb
Posted By: Twelve13
Subject: Problems with H3 carb
Date Posted: 29 Nov 2022 at 3:52pm
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Hello, I am in the process of getting a H3 running again, I can get the engine to spit and stutter and start to run, however, when it does it pops out some smoke through the carb and the exhaust and stops. I have tried switching the plug wires (from 1 to 4, 2 to 3, and so on) thinking I might have got the distributor put on 180 degrees out and it won’t start at all and the only thing it did was a much larger pop out through the carb (backfire?). I am not very familiar with gas engines (especially those with points and a distributor), I had it running a while ago but it would die if you took the choke off. I have tried the settings from the instructions that came with my carb kit of one turn out on both the needles, and I have tried putting the idle in one half a turn (where it is now) and also a few half turns out (where it was kinda running but the plugs looked rich). Does anyone have an idea of somewhere I went wrong and somewhere to go from here? I appreciate the help in advance! |
Replies:
Posted By: DiyDave
Date Posted: 29 Nov 2022 at 5:14pm
Pull the plug on bottom of carb, see if you have a good steady flow of gas. If not, trace backwards. Have you run a compression test?
------------- Source: Babylon Bee. Sponsored by BRAWNDO, its got what you need! |
Posted By: Eric B
Date Posted: 29 Nov 2022 at 6:38pm
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The minimum on the main jet should be 2 to 2 and 1/2 turns, and later fine tuning the main jet at full throttle. It's not impossible that the misfiring is from something else. ------------- Currently- WD,WC,3WF's,2 D14's B. Previously- I 600,TL745,200,FL9,FR12,H3,816 LBH. Earth has no sorrow that Heaven cannot heal! |
Posted By: doctorcorey
Date Posted: 29 Nov 2022 at 9:22pm
Gas engines usually backfire through the carb for these reasons. 1. Timing-firing order wrong. 2. Intake valve burnt or sticking open/ broken valve spring. 3. Exhaust valve not opening/flat cam/ bent push rod. 4. Extremely lean mixture. Try starting with one plug wire grounded. If back firing stops, suspect that cylinder. Try each cylinder until backfire stops. Engines that have sat for years often pick up debris on valve seats when they are brought back to service.  ------------- Semper Fi USMC 1958 HD6G, 1959 MF 203 loader, 1960 Case 420B Backhoe, MF 65 Tractor/Loader Diesel |
Posted By: Twelve13
Date Posted: 30 Nov 2022 at 3:46pm
| I appreciate all the helpful replies! I figured since I had the carb jets turned in too much, and because it was quick, I turned those back out a few turns and it came a lot closer to running! I will check the other things when I next get the chance in a few days. Does anyone happen to know the cold intake valve specs? |
Posted By: Eric B
Date Posted: 30 Nov 2022 at 7:20pm
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https://cdnmedia.endeavorsuite.com/images/organizations/5b5d9e04-fbf3-45af-b85a-10b411f696fa/Bills%20Tidbits/Engine%20Spec%20Chart.pdf%20" rel="nofollow - https://cdnmedia.endeavorsuite.com/images/organizations/5b5d9e04-fbf3-45af-b85a-10b411f696fa/Bills%20Tidbits/Engine%20Spec%20Chart.pdf
If this chart isn't a hot link you'll have to copy and paste in your browser as I'm not up to speed on the tech side. Personally, in this chart they have intakes at 8 to 10 thou... that's too snug for my liking. I had one valve that would leak when hot but fine when re-adjusted with just a bit more clearance. It was the previous owner that had set the valves too snug of a clearance. ------------- Currently- WD,WC,3WF's,2 D14's B. Previously- I 600,TL745,200,FL9,FR12,H3,816 LBH. Earth has no sorrow that Heaven cannot heal! |
Posted By: Twelve13
Date Posted: 03 Jan 2023 at 4:02pm
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After the holidays I finally got back out to working on it. I looked at the carb to make sure that it hadn’t gotten dirty since I cleaned it; and sure enough the fuel pump (that is bad anyway) must have been full of dirt or gunk because in the bottom of the bowl was a solid 1/4” of what looked like mud. So, I cleaned the carb again and it started right up. Now the questions that I have are related to the carb. When the engine shuts off sometimes fuel comes pouring out of the mouth of the carb. I have just cleaned the float seat and needle so I don’t think they are the issue, and I set the float the way that the instructions that came with the carb kit suggested. It is a new float because my old one was leaking, and this new float does not seem to leak. All that being said, other than a float issue I can’t think of what could cause such a large amount of gas to come out of the carb when the engine isn’t running. Also, what sets the upper limit of the rpm on the machine? When I got the machine the weights in the governor were gone, and I have since found some and replaced them. However, if I open up the throttle to full the engine really starts screaming and it sounds like it is going way too fast (I am waiting on a handheld tachometer). |
Posted By: DiyDave
Date Posted: 03 Jan 2023 at 5:23pm
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Better off to kill it by shutting off the fuel valve at the bowl, and let it fuel starve to die. Check your needle valve and seat for wear or a rubber tipped needle valve. Damned alcohol in the fuel eats the rubber up or makes it swell and not fit. JMHO... ------------- Source: Babylon Bee. Sponsored by BRAWNDO, its got what you need! |
Posted By: Eric B
Date Posted: 03 Jan 2023 at 7:41pm
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If the 1/4" layer of crud was in the bottom of the carb, it means that if you have a sediment bowl the screen is missing and in all likelihood the small debris coming through gets stuck in the needle and seat, until the tank is cleaned more keeps on coming. I've had issues like that but after installing inline filters the issue is gone for good. My model B has no sediment bowl at all, but a serviceable 'inline glass view gas filter' with a fine screen (Amazon), it's the last filter you ever need to buy for whatever you put it on. ------------- Currently- WD,WC,3WF's,2 D14's B. Previously- I 600,TL745,200,FL9,FR12,H3,816 LBH. Earth has no sorrow that Heaven cannot heal! |
Posted By: Twelve13
Date Posted: 03 Jan 2023 at 10:27pm
| I appreciate you reminding me to shut it off with the fuel, I completely forgot to! And that is right, the glad sediment bowl cracked when I tried to remove it for cleaning so I replaced it with an inline filter, as the tank had a bunch of gunk in it as well. I have cleaned the tank out, but the fuel pump itself looked to be full of stuff that must have made it’s way into the bowl |