Tuning Problems with my CA??
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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=19856
Printed Date: 10 Feb 2025 at 9:33am
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Topic: Tuning Problems with my CA??
Posted By: Larry in OK
Subject: Tuning Problems with my CA??
Date Posted: 24 Oct 2010 at 1:11pm
I've pretty well exhausted my limited mechanical knowledge fighting with my '52 CA.
So far the tractor is winning.
I've switched it over to 12v and that works properly.
The tractor starts easily and runs smooth from slow idle to full throttle, until I try to put a load on it.
New points and condenser, cap and rotor, new plugs and wires. New manifold and gasket, old one was just about rusted out. My 25 year old timing light no longer works but I've tried running it with the timing adjusted pretty much from where it won't run back around to where it won't run.
I've rebuilt the carb but I'm not sure about it yet, adjusting the idle screw has no effect.
The problem shows up under any load beyond the tractor pulling itself on level ground, starts spitting and popping back through the carb and will pretty much fall on it's face and die.
Am I still looking at carb problems or do I need to look elsewhere like the governor or possibly the mechanical advance inside the distributor?
Thanks
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Some people are like Slinkies. Not really good for much of anything but they still bring a smile to your face when you push them down a flight of stairs.
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Replies:
Posted By: DennisA (IL)
Date Posted: 24 Oct 2010 at 2:44pm
I had the same thing with my "CA". Found out it was bad gas. My uncle put a diesel/gas mixture in after they were done using it on the auger. I did the samethings as you before I found it was the fuel.
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Thanks & God Bless
Dennis
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Posted By: Charlie175
Date Posted: 24 Oct 2010 at 3:21pm
if you pull the choke does it clear out?
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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Posted By: Gerald J.
Date Posted: 24 Oct 2010 at 3:26pm
The idle screw having no apparent effect can come from two causes. The associated passage may be plugged, or most likely the governor is compensating for its effects. There are a couple ways to get around the governor besides unhooking it. One is to hold the throttle shaft closed against the idle speed screw. It helps to slow the idle speed below specification to reduce the throttle plate opening because any opening of the throttle plate kicks in the main jet a little. The other is with the governor in control, watch the throttle shaft and tune the idle jet for where the governor closes the throttle the most.
Same thing at high speed, but the governor has more power and its harder to override so its probably best to tune the main jet for where the governor closes the throttle the most. Then go back and adjust the idle again, they do interact so you have to do each one two or three times in the alternating sequence. Then you can check for smooth acceleration indication a rich enough main, and you may to run it a little richer to get that transition smooth.
For ignition timing without a light, you advance the timing until it will run at high speed under load and will accelerate that load (e.g. full throttle) without pinging. You really need to check to be sure the timing is advancing or you'll never get good running at all speeds. A light is the best way to accomplish timing. An engine without working advance runs poorly at most speeds because it needs more advance at higher speeds to compensate for the burning delay of the mixture, though a lot of magnetos don't including timing advance.
Gerald J.
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Posted By: morton(pa)
Date Posted: 24 Oct 2010 at 4:56pm
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Check, clean, and/or replace your fuel line. Had the same problem, did just that, and no more problems.
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Posted By: Larry in OK
Date Posted: 24 Oct 2010 at 5:14pm
Thanks for the suggestions.
I'm leaning away from fuel and fuel delivery to carb being the problem. Fresh clean gas, new sediment bowl and new fuel lines were one of the first things I did with this thing. but, I'll look it over some more.
In fact I managed to run it dry yesterday while dinking around with it. Of course I was 100 yards away from the shop and I'd just put new points in it so my natural assumption was that I'd screwed something up with that.
I had not thought about the governor over riding the idle screw adjustment so I'll try that next. I've pulled on the governor rod with it running and feel it pull back so it's doing something. As for the main jet, there is no external adjustment on this carb. (Zenith)
I also ran a compression check which showed me 125, 130, 125 and 135# 1-4.
Thanks for the suggestions.
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Some people are like Slinkies. Not really good for much of anything but they still bring a smile to your face when you push them down a flight of stairs.
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Posted By: 5Points
Date Posted: 24 Oct 2010 at 5:24pm
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Did you by chance put the carb gasket on upside down? I did that on one of my tractors once, which kept the idle screw from having any effect.
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Posted By: tom (OH)
Date Posted: 25 Oct 2010 at 6:30am
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I had a truck that acted like that and the points were not grounded, the ground wire was not connected.
Tom
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Posted By: ALinIL
Date Posted: 25 Oct 2010 at 10:59am
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Larry - My 2cents. Make sure your advance is operating in your distribator. I would check your timing with a lite. Also you have a zenith fixed jet carb. That can be a problem. My CA would spit and sputter until it was warmwed up. But still never run correct, seemed always to be lean running.. I changed the fixed jet to adjustable one and it cured the problem. - AL
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Posted By: Brian Jasper co. Ia
Date Posted: 25 Oct 2010 at 11:22am
I'm with Al on this one. The governor doesn't "Override" anything in the carb. If the carb has a problem with adjustments or otherwise it will "hunt". Fiddling with the idle adjustment only affects idle. At rated speed, the idle circuit does not operate. If you pull the choke out some and it runs better, you have either a vacuum leak, something restricting the main jet, or low float level. I had a long time A-C dealer mechanic tell me that you know when the timing is correct when you completely close the throttle from running at full speed and it gives one loud bang out the exhaust.
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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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Posted By: mlpankey
Date Posted: 25 Oct 2010 at 11:28am
you say it runs well at high idle and no load correct ?load it and it breaks up . Sounds to me its the spark breaking down . Did you adjust the distributor timming by ear with the tractor at high idle so the mechanical advance was all in?
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people if they don't already know it you can't tell them. quote yogi berra
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Posted By: john(MI)
Date Posted: 25 Oct 2010 at 11:28am
Did you forget to re-install the governor spring when you replace the carb? It goes from a linkage on the backside of the carb, forward to a manifold stud and should be quite long and appoximately 3/4" diameter.
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D14, D17, 5020, 612H, CASE 446
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Posted By: CTuckerNWIL
Date Posted: 25 Oct 2010 at 12:06pm
How about going back to the beginning. You said you changed it to 12 volt. Did you change the coil? If not 12 volts will heat the coil up and weaken your spark seriously if not fatally.
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http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com
Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF
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Posted By: pumpkin man
Date Posted: 25 Oct 2010 at 8:51pm
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put a ballest restor b 4 the coil had the same problem when I changed over to 12 v even if you have a 12 v coil
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Posted By: Larry in OK
Date Posted: 26 Oct 2010 at 3:02am
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Haven't had a chance to mess with it again but thanks for the suggestions,
Governor spring is in place
Ballast resister for the coil is in.
Probably be Wednsday before I get to fool wit it again.
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Some people are like Slinkies. Not really good for much of anything but they still bring a smile to your face when you push them down a flight of stairs.
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Posted By: Larry in OK
Date Posted: 06 Nov 2010 at 7:22pm
Well, its been a few few days since I had a chance to tinker with the CA but today was a good day for it. I figured out my problem and corrected it.
I'm almost embarrassed to admit what was wrong but I'll fess up anyway.
My only feeble defense is that when I put the new plugs and wires on it I put it back just like my uncle had left it but as it turns out the #2 and #3 plug wires were swapped. I figured it out when I was putting the distributor back together after verifying the advance weights were OK.
One of them there epiphanies smacked me in the back of the head, this thing rotates clockwise and if it rotates clockwise then the plug wires ain't right. I finished buttoning it all up and when I pulled the starter rod there was no doubt that it was fixed.
The old girl has some attitude about her now.
Thanks for the suggestions and I'm sure I'll have more questions with this thing.
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Some people are like Slinkies. Not really good for much of anything but they still bring a smile to your face when you push them down a flight of stairs.
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