Farm Equipment - Wild Surging

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Wild Surging

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=9204
Printed Date: 02 Nov 2025 at 9:30pm
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Topic: Wild Surging

Posted By: Ken in Texas
Subject: Wild Surging
Date Posted: 09 Mar 2010 at 9:03am

I have not had this happen before. I overhauled a CE engine and it now surges out of control whenever you manually increase rpm or the governor increases rpm. It may or may not eventually settle down. It has a battery ignition. The anti surge spring seems to do nothing to control the surging.

I have a CA with a Battery Ignition that is as happy and snappy as all get out and I wish everything I have that runs and drives would be as normal as my CA

Where do I look first to solve the surging problem. I also have a feeling that at full throttle I'm not turning up maximum rpms.

It is partially pulled down now for painting and pulling the governor off for a look see will be easy. I have a feeling the surge problem is a governor problem. This is a C and it has run a little bit before overhaul on both a Mag and a Distributor with the same governor. Actually just long enough to detect a knock.

The ignition is not the same unit as shown in my C/B/CA parts books. It has a skinny short neck between the base and the upright distributor itself. It came to me with this distributor on it.

Replies:

Posted By: GlenninPA
Date Posted: 09 Mar 2010 at 9:40am

Ken,

I think I would check the pins and weights in the governor for wear first. It sounds like they are not able to swing back and forth freely?

Posted By: Gerald J.
Date Posted: 09 Mar 2010 at 9:51am

A really badly set carburetor will cause surging. Probably something like idle mix way off so it practically dies and the governor pulls the throttle open then the power mix way off so it has lots of power. Lean idle, rich run would be the case.

Try direct throttle plate control over riding the governor. At idle with throttle closed adjust the idle mix for the fastest speed, then holding the throttle plate for a pretty good speed, adjust for the fastest speed. They will interact so repeat a few times. Or with the governor working, adjust for minimum throttle at slow and fast speeds.

And it could be a sticky set of ignition advance weights or the wrong advance curve. besides a sticky governor.

Gerald J.

Posted By: Dick L
Date Posted: 09 Mar 2010 at 11:37am

Fraid the idle adjustment miss stated. Idle adjustment is to get the slowest rpm possible with the lever all the way back. If you have an adjustable power jet you set the throttle wide open and adjust to the fastest rpm possible and then turn it back in until you see a slight rpm drop.

Remember when you are at idle the governor cross over arm needs to have about 1/16" pressure on the closed butterfly. That is checked at the linkage connection up by the fan.
If you do not have that pressure holding the butterfly closed it will cause surge.

I see many times people explaining how to set the crossover arm say it backwards.
That is why I explain the function that you want to end up with. The governor has to hold the butterfly (closed) at (idle)

Posted By: Gerald J.
Date Posted: 09 Mar 2010 at 1:28pm

NO! You want the fastest IDLE speed adjusting the IDLE MIX with the throttle held closed. The slowest idle speed is not running at all. Which can lead to surging.

Gerald J.

Posted By: Dick L
Date Posted: 09 Mar 2010 at 8:36pm

Sorry Gerald! That is just not how it works.

The word idle means (slow) I don't know where you came up with that Idea. Fast idle is above idle and the adjustment screw can be removed and put in your pocket. As soon as you open the butterfly above slow idle you are out of the (idle circuit) and on the power jet.

The way you adjust the (idle) is to close the butterfly and the idle adjustment screw alternating back and fourth until you get to the slowest (idle) possible and keep the engine running. At that point you do not want to change the adjustments. When you open up the butterfly with your throttle lever and more air is drawn thru the venturi it starts drawing fuel up the feeder tube from behind and thru the power jet. At this point the idle adjustment changes will have no affect. That is until you want to idle the engine. This happens when the butterfly is blocked slightly open by the setting of the stop screw on the back of the carburetor.

Posted By: Gerald J.
Date Posted: 10 Mar 2010 at 12:24am

Then for 60 years I've been doing it wrong and I can't believe that.

Yes when adjusting the idle mix you need the throttle closed all the way, but with the throttle closed all the way way and held there you want the engine speed to be maximized by the mixture adjustment. That's when its running most efficiently, that the mix is optimized. You minimize the engine speed with the throttle, but maximize it with the throttle held closed by the mixture adjustment.

Even if you get the idle speed screw backed out and the throttle closed all the way, there is some interaction between the idle and the power circuits in the carburetor so you have to go back and forth a couple times. And to add complication, the gasoline level in the float bowl affects both and the transition from idle to run.

Gerald J.

Posted By: Dick L
Date Posted: 10 Mar 2010 at 5:12am

If you have adjusted carburetors for 60 years and it worked keep doing it. If they work well then it is the terminology you are using.

By the way I don't use surge springs on my B's and C's and I don't have a surging problem.

Posted By: Ken in Texas
Date Posted: 10 Mar 2010 at 8:32am

I have a AC publication (Manual) called "Knowlege Means Power" - Farm Equipment Service Manual. For "G", "B/C" and "CA"Tractors.

I'm going to use it to see what the procedures they outline are for carb and governor adjustments. Can't do much actual adjusting with the tractor stripped down for painting but I can maybe get a clearer idea of what you two guys are surging back and forth about. lol

I can stop the surging at any hand throttle setting by steadying the link between the governor arm and the carburator with my hand. Quickly increasing or decreasing the rpms with the throttle setting and surging happens. I tend to think the carb is not the culprit. If the surging happens while in the drivers seat it gets pretty wild especially in third gear.

Posted By: GregLawlerMinn
Date Posted: 10 Mar 2010 at 9:03am

I would inspect/adjust the govenor arm to throttle rod adjustment 1st. Easy to do when radiator is off, and, it is not all that uncommon to see where a previous owner bent the govenor rod (to get more rpms??). I bend the govenor rod so that I have 1/16" gap between the govenor rod and throtle rod when the throttle is in the botttom idle notch and the carb is against the idle stop (I think this is what Dick L is recommending). Then install the anti surge spring (small end thru the throttle rod, large loop over the top manifold stud just forward of the hole thru the throttle rod). If still experiencing surging inspect/repair the govenor weights/pins. The weights should rotate smoothly and the hole were the pins go thru should be round and not egg shaped. The govenor rod should also move smoothly where it exits the cover and be tight in its bushing. You should also see signs that a small amount of oil is coming into the govenor from the little oil line (I always remove the oil line and clean it out with brake cleaner and air).

Posted By: Steve in NJ
Date Posted: 10 Mar 2010 at 11:50am

These carburetors have two different circuits in them. Idle mix, and enrichment. The way you adjust them is the way Dick L. has mentioned. Also, Dick mentioned, once the throttle blade is opened, fuel is no longer pulled from the idle circuit. That is absolutely correct. Fuel now is drawn through the emmulsion tube or "nozzle" and you are now in the enrichment circuit till the throttle blade slams shut again. Float level does have an effect on both circuits, but as long as your close with the level you should be okay. I don't have any surge springs on my B Tractors either. I'm not sure if a sticking distributor wieght(s) will have any effect on surging. If the wieghts stick, to me, it'll be super tough to start. Once started, (if you can get it started) depending on the engine, it will probably not idle or run well because the wieght(s) are stuck in the advance position till they flop back. An out of adjustment carburetor can add to a surging problem, but my first instict would be to do a govenor inspection, and check to see if it is indeed adjusted properly whether the problem be in the linkage or the governor itself. I would think, after spinning around in circles for 50 +years, I'd be a little worn out to! lol! Once the govenor has been inspected or repaired and is working normally, if a slight surge still exists, next would be to dial the carb in a little better and see if this eliminates the surge once n' fir' all.... Good Luck Ken. Lets us know how you make out.

mailto:Steve@B&B - Steve@B&B