[AJD] What a day - Galloping idle - Backfires

Duane Larson jdlarson at comcast.net
Mon May 30 20:47:41 PDT 2005


LeRoy,
A couple of thoughts.  Just driving around with your 40W will not cause the 
load circuit to play a significant role as most fuel will be drawn through 
the idle circuit.  The idle adjustment is located just below the flange 
where it is bolted on.  Remember that the idle needle controls the air, not 
the fuel, so turning it in makes the idle mixture richer.  The load needle 
can  best be adjusted when the tractor is under load, and Bob did that when 
running your carb on his test engine.  He also set the idle needle at that 
time.  Default settings are 2 turns out for both idle and load.  You can 
simulate a load condition by running the engine wide open, adjusting the 
load needle till it runs smoothly, then opening it another 1/2 turn, but 
that should be close to Bob's setting.

You might also adjust the idle stop screw if it is searching at idle - turn 
the screw in against the stop pin until it runs smoothly.

Finally, you might also check the rod from the governor to the carb linkage 
for proper length.  Disconnect the linkage at the carb, push the throttle 
lever to the wide open position, hold the carb throttle shaft in the wide 
open position, adjust the rod length until the rod just slips in the carb 
throttle shaft, then shorten the rod two turns at the ball joint and insert 
the rod in the carb throttle shaft.

As noted elsewhere, fresh fuel and plugs are also good.
Regards,
Duane Larson

----- Original Message ----- 
From: "LeRoy Price" <lep at epix.net>
To: "Antique John Deere mailinglist" 
<antique-johndeere at lists.antique-tractor.com>
Sent: Monday, May 30, 2005 6:11 PM
Subject: [AJD] What a day - Galloping idle - Backfires


>
> Guys,
>
> Well the plan was to get the tractors running today and a thunder shower 
> stopped me at 6Pm.  Anyway, I did get to start and rung the JD BO.  It ran 
> well.
>
> I then got my stuff together in a wheel barrow and off to the field I went 
> (tools, 3 batteries, gas can, a carb and the mag).  Thats where I have the 
> tractors under tarps.
>
> I just got my JD 40W carb back from a Robert's rebuild, looked nice.  But 
> before getting into the JD 40 I went I figured I better start with the 
> Ferguson 40.  Got the mice nest out, popped in the battery, a little gas 
> and it started after about 3 trys.  I drove it around a bit and then 
> parked it and let it run.
>
> Soooo, while that was running I uncovered the JD 40W and started to put 
> the carb on.  Got it on without issue but will need a new gas line, leaks 
> near the bowl.  Put some gas in it and started it.  It started on the 2 
> try and ran pretty good so I drove it around.  What I noticed was a little 
> gallop in the idle.  So I got out the manual and started tweeking, noting 
> where it had been set.  The interesting thing is that no matter where I 
> adjusted the load needle I couldn't hear a difference in the idle.  After 
> about 15 minutes of tweeking I had this thing back firing like nuts. 
> Haven't a clue why and was wondering if someone could help.  It seems that 
> when the throttle was on full open the idle seemed to gallop and soon 
> after it backfired.  I adjusted and adjusted but it wouldn't change.  So I 
> tried to get back to the settings it had when I started.   I restarted it 
> and it seemed to be better but its still sort of gallops.  By gallop I 
> mean it runs and then there seems to be a!
>  pause and then it picks up again.  When it picks up thats when it 
> backfired.
>
> Any ideas?
>
> LeRoy
>
> _______________________________________________
> Antique-johndeere mailing list
> http://www.antique-tractor.com/mailman/listinfo/antique-johndeere 




More information about the AT mailing list