48 A gallop during idel

Mark

Many think first of the governor and/or its linkage with the carburetor when in fact it is the governor, working as it should, that is keeping the engine going! And what so many do not realize is that there are five distinct individual pathways to check so as to ensure the IDLE channel is clear. And if there is anyone out there who needs further information on these little guys, write me. (PatB)

Still need to hear if the idle screw has any affect, but re-installing the governor case on the main case, any adjustment of the governor shaft endplay, weight replacement, bushing replacement, or bearing adjustment/replacement, should end with checking the proper length of the speed control rod. The book says so, too.

The governor might well be working in action and reaction, but the improper rod length might cause the carburetor to ingest more fuel than the governor meant to signal, the engine overspeeds, the governor slams shut, the carb closes too far, the engine slows to a stall, the governor signals open, the engine injests too much fuel, the governor detects the overspeed, it slams shut, rinse and repeat.

Now, to the owner. Take the rod loose at the carburetor and hold the carburetor butterfly still with your left hand and see if when you hold the throttle plate steady if the engine tries to stall. If it runs fine, it is the governor causing an over reaction. If it cannot sit still against the throttle stop and idle correctly, it is most likely on the carburetor side.

I just think there are a lot of things to check without even using a wrench before you can even attempt to properly diagnose this case.

Frank

Frank, From your input, I would not expect the governor to carbutator linkage to be adjusted correctly. In addition to the governor work, it has a different carburator and manifold (of a different type) The stack up is bound to be off. I will make the correct adjustments as you described.

I will post back with success or remaining issues. Thanks again, Mark

Secondly -- yes, there are some subtlties involved in clearing the IDLE pathway if you should find it closed. And I suspect you will. The hunting or throttling of the engine during idle indicates fuel is being drawn by the engine via the LOAD side -- something not normal during IDLE because during IDLE, the butterfly is usually very near closed! As engine speed drops for lack of fuel, the governor opens the throttle butterfly so as to draw more LOAD fuel. The engine speeds again, and this cycling repeats as often as needed to maintain RPM.

There are no less than five distinct passages you should be concerned about. You can find data on three of them over at Robert's Carb Site -- scroll down to Technical Information, then go to Tractor pulls ok but won't idle well. But there is no data given on the primary & secondary IDLE orifices. If you want more than you find in the Carb piece over at the JD-H Site, e-mail me for some added data -- you can contact me from the JD-H Site. (PatB)

• Robert's Carb Repair

Throttle lever in wide open position, carburetor throttle plate/butterfly in wide open position, rod detached, rod should be 1/2 hole short of enaging the throttle arm hole. When you pull on the governor rod to force it to engage that preloads the governor action so that everything is play-free, but not too tight.

Does the idle adjustment have any affect on the engine, i.e. does it lean it out at idle or conversely, richen it? Does applying extra fuel via the choke smooth out the loping? If so, you probably have the carburetor assembled correctly, with no clogged passages, and since it runs so well under load, that side is likely all right. If choke helps, you have a blocked passage more than likely.

Check that rod. I bet that after the governor work it requires a new length. But, if you can't say that the idle mixture screw is having the correct affect when turned, you might have a plugged idle side passage.

Frank

Go to the JD-H Restoration Site, and once there, look over on the left side, find CARBURETORS, and do a one-click on it. Wait for the PDF document to come up. The whole document makes for a neat read on JD carbs, but if you page in to (I think) page 7, you will find a section called, Testing -- LOAD & IDLE Pathways. Run that test and please post back & we can take it from there. (PatB)

• Restoration Site, JD-H