45 A rpm issues

bigboreG

Member
My old slant dash has a weird issue. It
runs very well and has great power. Also
idles good. But when sitting at WOT it
will try to run away if I open the load
screw a couple clicks from 1 1/2 turns
open. I put a 71 carb on it when I
overhauled the engine and fitted with alum
pistons. The carb is not dirty I have been
thru it recently. It will run on the idle
circuit like it should when I close the
load screw. But why is it trying to run
away? When under load the governor is very
responsive and works as it should.I should
add that I just bought this tractor BACK
from a guy that I sold it to right after I
overhauled it. He was in a bind and needed
cash. He had the clutch apart once and
when I got it back it shook bad . He had
not timed the driver to the crank. How
long he ran like that I don't know. Think
anything got damaged from that?
 
Possibilities:
Idle stop pin bent forward not allowing throttle blade to close.
71 carb may have came from a magneto ignition "A" where the proper stop procedure is to pull throttle all the way back, and someone bent the pin so engine wouldn't die.
Idle speed screw turned in too far.
Excessively worn throttle disc.
Improper adjustment of Rod connecting governor to carb.
 
Since you can run it at fast idle and turn load needle shut and stays at fast idle and runs even then that proves your idle circuit/ports and idle needle adjustments are correct.If it idles perfect at low idle/same as above and shaft/bushings/blade are in good shape. At fast idle, one can actually open idle needle far enough to make it falter (too rich) that's how you know to turn it back in to get it right. This all proves that you don't need and don't want any fuel from load side while at fast idle or any idle speed. Where I'm going with this is this , if you give it more fuel with the idle needle it will falter,NOT run away, so if opening up the load needle were to give it more fuel (which it doesn't and shouldn't at fast idle)it would do the same thing, it would falter, NOT run away. Running away is totally a function of throttle blade position. Like Poppinjon said , check proper adjustment of governor rod to throttle and make sure no binding , check stop pin/adj. screw and another thing to check is this. When running at fast idle long enough in the right weather conditions, ICE will form on outside of carb and entry to manifold. It ALSO forms inside and I have seen it cause the throttle plate to stick until the governor would overcome it and pop it loose. Bottom line here, an I think poppinjon would agree , if the governor is working correctly and link rod adjusted right and nothing binding , no amount of fuel you can give it will make it "run away". At correct fast idle , the governor rod holds the throttle plate barely off closed just enough to uncover 3 tiny pin ports (#71) and the fuel/air ratio controlled by idle needle setting. That setting doesn't give more or less rpm, it just adjusts the fuel/air ratio so it runs even. I don't believe , based on the exact info you gave us, that the load screw has anything to do with your problem. Linkage/gov./ice.
 
Engines speed up like that from running lean, not rich. There are several carb issues that could cause that. But the governor will then slow it down & it will hunt.
 

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