Ford NAA Keeps Surging

fordfx413

Member
I finally got my NAA back together and half ways running good. I put new plugs, wires, points, cap and rotor. I also rebuilt the carb. OK so when im running between 1200 and 1600 it starts to drop then rev up drop and rev up and so on. I adjusted the power needle on the carb, srcrewed all the way in the out 1 turn. Same thing with the idle screw. When im running it at 1800-2100 it runs fine, no surging. I checked the distributor timing at 8 degrees and it was pointing right at number one. I hooked up my timing light took the tractor to 2100 and 8 degree line was perfect with the arrow. Anybody else had this problem or no of a solution? Thank you!
 
Also when warm when i shut it down and try to restart i have to choke it for a second then it fires right up.
 
You MAY have other problems, as well (gov adjustment or carb problems), but (IIRC) timing is supposed to be about 8º at idle and 29º to 31º at high idle.

8º at 2100 RPM won't cut it.
 
fordfx413.......first off, learn to adjust yer M/S carbie.......adjust yer spring loaded main-jet to 2-turns and LEAVITT!!! Then adjust yer side pointing idlemix for FASTEST idle, NOT smoothest idle. Understand the difference?

Yer description of surging, is characteristic of LEAN burn. ADJUST yer carbie and report back, you may have governor problems but do yer carbie FIRST .......Dell
 
Ok I got the dist' corrected. I will adjust the power screw to 2 turns then the idle screw im a little confused about, Dell What do you mean about the fastest idle?
 
I'm not Dell, but here's what I believe he means.
With the throttle shut all the way down to idle, less than 500 RPM,
set the idle mix adjustment for the highest RPM. Then re-adjust
the idle speed screw and repeat the idle mix adjust for highest
RPM. If you can't get it down to 500 RPM there's still something
wrong with the carb. Plugged passage, etc.
 
fordfx413.......what do I mean by fastest idle? GUESS???......sheesh!!!.......SLOOooly adjust the side-pointing idlemix in and out for FASTEST idle.....ie....470 is faster than 450.....which is faster than 430 and slower than 500.....caprice???

While the M/S carb instructions say 1-turn fer idlemix that is WAY too much fuel ...ie... RICH. Generally the optimum idlemix screw is probably about 1/8-turn from full CLOSED. But each carb is slightly different, that is why there are adjustable tweek'ums. And that is also why we recommend 2-turns fer down-pointing mainjet and LEAVITT.

Bottom line, the starting drill is.....2-turns on the GLASS filter screw, throttle lever about 1/4, ignition switch ON, engage BIG starter switch by tranny shifter for 2-rumpa-rumpas and finally a QUICK pull on yer spring loaded choke knobby. Tractor should fire right off. Now fiddle with yer choke knobby to keep yer cold engine running. Shouldn't take more than about 2-mins to warm up. ........HTH, Dell
 
Im guessing im still having carb issues. I cannot get it to idle at 450 rpm it will drop to 300 and go up to 600 and keep doing that. I adjusted the main screw to 2 turns and if i try to adjust the idle mix screw anywhere from all the way closed it will die. I have to have the idle screw all the way shut to run. When it was bouncing around 450 rpm my timing was about 20 degrees on the flywheel. I read in the manual i just got and it said to be between 6 and 10 degrees at 450 rpm. So i adjusted to 8 degrees at around 450 rpm but when i did that 2200 rpm was about 25 degrees. Do i still have carb problems or what? I cleaned entire carb and put in a new kit. The exhaust just sounds like it is running ruff. I have never really been around these tractors so i have no idea what they sound like when there running good.
 

If it won't run unless your idle needle is turned all the way in, where the engine should be rolling from too rich a mix, then you may be sucking air at the carb throttle body (base) or at the intake manifold.
 

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