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1957 Ford 640 loses power under load.

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Scot Webb

02-25-2002 05:36:11




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The tractor starts and runs just fine under no load. The carburator has been recently rebuilt and new wires, plugs, cap, and points installed last year. The tractor was warmed up and I took off in first gear and it seemed fine. However as I tried higher gears (2-4) the tractor started to labor more and more. I had it running at full throttle (about 2400 rpm)in fourth gear and when I took off it almost died. Once I got moving a little bit I let the clutch out completely and the rpms never could get about 1100 at full throttle. As soon as I pushed the clutch it the engine returned to 2400 rpm. Could stale gas cause this problem? Also, could a low level in transmission fluid cause this? Any help would be greatly appreciated.

Thanks

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charlie

02-25-2002 14:36:18




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 Re: 1957 Ford 640 loses power under load. in reply to Scot Webb, 02-25-2002 05:36:11  
scott,hear me out before you think i'm nuts.does it have a step-up box.i had a similar problem a while back with my 601.my nieghbor wanted to borrow it to bring in some firewood.i never loan it but he ain't a bad guy so i thought what the heck.i got concerned after about an hour so i goes to check.he's at the bottom of the hill and can't get any power to get to the top.i get on and try and have trouble myself.i just happen to look down at the side and notice that he's put it in the over range.shifted it back to standard and she came home with no problem.

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Scot Webb

02-25-2002 19:41:37




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 Re: Re: 1957 Ford 640 loses power under load. in reply to charlie, 02-25-2002 14:36:18  
Upon further investigatinn I noticed I could hear a snapping sound coming from the ignition side of the tractor. I shut the lights out in the barn and sure enough it was arching from the two electrical points hookup points on the coil to the center electrode of the coil. It would arch right through the plastic housing just below where the boot from the coil wire was so I think the wire is fine but the coil is bad. What are your thoughts??

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Scot Webb

02-27-2002 08:37:25




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 Re: Re: Re: 1957 Ford 640 loses power under load. in reply to Scot Webb, 02-25-2002 19:41:37  
Replacing the coil helped but it was still not firing on #4 cylinder. I changed the plug out and it is running fine now. Thanks for all of your help!!



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Fighting suburbia in NC

02-25-2002 07:30:34




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 Re: 1957 Ford 640 loses power under load. in reply to Scot Webb, 02-25-2002 05:36:11  
Could be bad gas. Try using the choke when it starts to bog and see if it picks up a little engine speed. It could be that the idle circuits are OK in the carb but the run circuits are obstructed by junk. Using the choke causes more vacuum to suck gas through the run circuits and evens out a lean condition. (An old mechanic used to call that a "Jewish rebuild" because it was a cheap way to dislodge crud in the internal circuits without tearing into the carb.) However, it will not run under load very well like that. Check to make sure that there isn't any water in the carb bowl from condensation. I once had a tractor that would not run sideways along a hillside because the water would slosh over and get in the pickup for the jets. It would run flat and straight up or straight down hills fine. Go figure.

Also check the ignition, especially the coil. A weak spark will run fine at idle and die under load. More "carb problems" are found in the distributor and ignition than in the carb. It is probably something simple, ya' just got to fgure out how simple. LOL.

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CapnDean

02-25-2002 09:07:29




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 Re: Re: 1957 Ford 640 loses power under load. in reply to Fighting suburbia in NC, 02-25-2002 07:30:34  
Agree with NC with regard to the number of "carb problems" that are found under the distributor!

Dean



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CapnDean

02-25-2002 07:26:18




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 Re: 1957 Ford 640 loses power under load. in reply to Scot Webb, 02-25-2002 05:36:11  
Try pulling one plug wire at the time and running the tractor. See if you notice any change. Sounds to me like you are either not hitting on all 4 cylinders....OR you have some serious drag in the transmission/axle/brake arena.

You can rule out the brakes by seeing if you can make the tractor coast any. The transmission (say a siezed bearing or something) could be binding causing a stressful load.

Sounds to me though like an ignition problem or maybe even fuel delivery... A carb float problem will starve the motor for fuel under load.

Hope this helps!

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