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LA idle

T

tah0026

New User
I purchased a LA about a month ago and can not get it to low idle. Currently idles at above 2800 rpm. I've rebuilt the carb but no change. Any suggestions.
 
If the carb is cast iron, boil it in lye water for a while I did one 3 times before the water stayed clear. It would idle down to where the impulse on the mag was snapping & it still ran.
 
Do you mean it "dies" if you throttle it back to idle, or that it WILL NOT slow down to idle speed?

If the latter is what's going on the linkage between the carburetor and the governor is not set to the correct length or there's something wrong with the governor itself.
 
It wont slow down. I'm wondering if there is an air leak from worn rings or valves. Do you know what the compression should be?
 
I soaked the carb for a couple of days in a carb cleaner bath, compressed air dried it, ran carb cleaner three times through it un till it was clear and redried it.
 
Since this is an old low-compression flathead engine I'll throw a GUESS out there as to a compression reading, probably in the 90 to 110 psi range???

That being said, I have newer personally encountered or even heard of an engine failing to slow down because of a valve or piston ring related low compression issue.

Have you verified that the throttle plate closes fully before installing the carburetor and that the carburetor-to-governor linkage is set up so it can fully close against the idle speed screw when installed?
 
The throttle plate screw it all the way in leaving approx. 1/8 of an opening. I'll try taking it out to close it and see what happens. Are you familiar with LA's?
 
(quoted from post at 14:26:12 01/11/21) The throttle plate screw it all the way in leaving approx. 1/8 of an opening. I'll try taking it out to close it and see what happens. Are you familiar with LA's?
Click to expand...

The throttle plate needs to be closed a lot "tighter" than 1/8" of an inch for it to slow down, probably within .015" to .025".

In answer to your last question, I am not as familiar with all aspects of LA's as I am with the carburetor.

That Marvel Schebler series was used on MANY makes and models over MANY year.
 
The reason I ask is that on the governor there is a large stiff spring that connects both arms. There is an additional hole on one of the arms that just seems to me to be for an additional spring. I also own a 420T and I know that both tractors should be idling at approx. 600 rpm. very distinctive sound in idle.
 
That 1/8 gap is to much. You need to turn it out to get the idle you like. On them la tractor be sure that the cable for the throttle is not sticking and pulling on the spring that is on the govern. When the tractor is off the linkage arm should move back an forth free. Also checkout the carb to see if the shaft that the butterfly inside the carb is not worn out and moves up an down because if it does then it will suck air and run fast at idle.
 
Check your carb to governor linkage and make sure it is set per the manual. Make sure it moves freely. If you set the end with the stop screw and cotter too tight by the governor it cannot move freely and can bind. Also, make sure the cotter pin is not catching or binding the way it is installed on any of the linkages.
 
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