ford 860 running lean

jvbama77

New User
Hey guys I'm new to the working on this Ole boy. Last year while bush hogging it died and the only way I was able to keep running to park it was with starter fluid. Ok all ignition parts are new and I rebuilt the carb. My problem is it only wants to run lean as in the mixture screw all the way in. I'm not a certified mechanic but do know to lean is not good. I've done all I can think and read. Any help is much appreciated thanks
 
Welcome to the forum. Lots of knowledge and great info from
the guys on these boards!

Since you put in all new ignition parts, you should have good
blue/white spark to the plugs, but it is quick and easy to check
that to make sure.

As long as the spark is good, check fuel flow to and through the
carb. Easiest place to start is probably just to pull the drain plug
out of the bottom of the carb. Catch the fuel in a clean glass
container so you can see if it has dirt or water in it.
Let the fuel run for a few minutes. It should run steadily and not
drizzle. You should collect roughly a pint of gas in a couple minutes.

If that flow isn't good, try it again with the gas cap off the tank.
If still not good, try at the line going into the carb.
If that isn't good move up the line and check.

If it is good, fuel may not be getting through the carb.
Before we dig into that though, which mixture screw are you
talking about? The main/large one or the small air adjusting
screw? The small one works backwards. In to Enrich.
 
Yes have good spark and ran all new fuel line with in line filter, I got rid of the glass catch can and even took the strainer off inside the tank to see if that was restricting fuel flow. I've redone the carb twice with new kits. I'm stumped and so is everybody else. I have rebuilt several holley carbs with good luck, as simple as this is I should not be having this issue but as soon as you rev it up it get hott!!! and you can hear the pinging going on with the valves. Has got to be something simple but I'm lost
 
Check the fuel flow.
Pinging and heat could very well be timing.

Put the original parts back on and lose the inline filter now
that you've proven they weren't the problem to begin with.
They've worked fine for 60+ years no need to re-engineer.

If all else fails, I rebuild these carbs and can do it for you.
I would just as soon help you fix it though.
What are your two adjustments set at now?
 
Symptons such as you describe can be caused by installation of an in-line fuel filter not designed for a gravity flow fuel system.

Unless you are CERTAIN that your filter is intended for gravity flow systems (very few are), get rid of it and replace the factory system.

Dean
 
The small idle screw I have it one full turn out, the bigger main mixture screw I've started as far as 2 full turns out and it just don't want to run without being almost all the way in. I have new points, rotor, cap, wires, plugs, the coil was bought last year. There isn't any play in the distributor than I can tell, feels good and tight. Have kno idea about the timing, it was running fine all last year then just would not stay running without starter fluid being sprayed to keep it running
 
(quoted from post at 10:00:05 09/29/15) Symptons such as you describe can be caused by installation of an in-line fuel filter not designed for a gravity flow fuel system.

Unless you are CERTAIN that your filter is intended for gravity flow systems (very few are), get rid of it and replace the factory system.

Dean
Thanks I will try that. Maybe the screen in tank was so gummed up that it was restricting the flow. It's actually running better with the setup I have now as far as not blowing fire out of the muffler but still will not hit the rpms it needs to. Thanks for the help
 
(quoted from post at 19:36:01 09/29/15)
(quoted from post at 10:00:05 09/29/15) Symptons such as you describe can be caused by installation of an in-line fuel filter not designed for a gravity flow fuel system.

Unless you are CERTAIN that your filter is intended for gravity flow systems (very few are), get rid of it and replace the factory system.

Dean
urning the main power adjust in is closing down fuel, thus leaning the mixture, so, if that makes it better, then it must have been too rich to begin with! Don't believe me? Then turn it in until it seats and it will shut off ALL fuel, even for idle, and engine will die. Does not sound like a filter or fuel starvation problem to me.
 
That's what I'm saying for it to run good you half to turn the main mixture screw all the way in then it runs good but starts pinging and gets real hot real fast! I'm no expert shade tree mechanic but I usually can figure things out but this has several folks stumped
 
(quoted from post at 17:48:32 09/30/15) That's what I'm saying for it to run good you half to turn the main mixture screw all the way in then it runs good but starts pinging and gets real hot real fast! I'm no expert shade tree mechanic but I usually can figure things out but this has several folks stumped
f you can turn the main power mixture screw all the way in until seated & it still runs, then something is seriously wrong inside the carb.....maybe just too high fuel level or maybe a bad seal at the gasket joining upper & lower. Is that a fact that it still runs with main power adjust hard seated?
 
Haven't had the time to mess with it until now so here is what I have. I removed the in line filter set the main mixture screw to one turn out then started it. Idle was great. Revved it up and it started running rough, turned the main mixture screw all the way in even until it was seated and it ran alot better other than the heat coming from the exaust and the pinging. This carb is too simple for me to be having these issues I think.
 
(quoted from post at 18:20:57 10/05/15) Haven't had the time to mess with it until now so here is what I have. I removed the in line filter set the main mixture screw to one turn out then started it. Idle was great. Revved it up and it started running rough, turned the main mixture screw all the way in even until it was seated and it ran alot better other than the heat coming from the exaust and the pinging. This carb is too simple for me to be having these issues I think.
"turned the main mixture screw all the way in even until it was seated and it ran alot better"
As I already stated, if this is the case, then there is a serious problem with the carb, as "all the way seated" will stop ALL gas flow into the idle AND power/running circuits & thus kill the engine.
 
(quoted from post at 17:38:24 10/05/15)
(quoted from post at 18:20:57 10/05/15) Haven't had the time to mess with it until now so here is what I have. I removed the in line filter set the main mixture screw to one turn out then started it. Idle was great. Revved it up and it started running rough, turned the main mixture screw all the way in even until it was seated and it ran alot better other than the heat coming from the exaust and the pinging. This carb is too simple for me to be having these issues I think.
"turned the main mixture screw all the way in even until it was seated and it ran alot better"
As I already stated, if this is the case, then there is a serious problem with the carb, as "all the way seated" will stop ALL gas flow into the idle AND power/running circuits & thus kill the engine.
On my 860 I found I had several vacuum leaks causing the engine to run lean. I replaced all the gaskets on the intake/exhaust manifold, including the ones between the manifold and engine and the carb gasket. Cured my ills. Not sure it will be your problem, just thought I would throw it in.
 

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