Ford 8n misfiring

When the tractor is on low idle it misfires pretty bad
but as I increase the rpm it starts to go away what
could this be?

Burned or leaking valves.Do a compression test wet/dry to locate/pinpoint the problem.

Check the easy & obvious first: firing order (1-2-4-3, CCW) and loose/defective plug wires.

A compression test is easy to do & as Den said, it will answer a number of questions about your problem.

First, take a look at the picture. If your gauge has a fitting that screws into the spark plug hole & the hose from the gauge screws into the fitting, do yourself a favor & get a brass elbow at the hardware store. Screw the fitting from the compression gauge into the head, the brass elbow into that, & the gauge into the elbow. Makes it easier to fit under the gas tank. (hint: take the gauge & fitting w/ you to the hardware store!)

Minimum acceptable pressure is 90 lbs w/ the lowest pressure reading w/in 75% of the highest reading. Run the engine to operating temp, turn it off, remove all 4 plugs, remove the breather hose & make sure the choke and throttle are both open. Crank it at least 5 compression strokes or until the gauge stops moving. Write down the first compression reading (that is the valves seating) then write down the reading after 5 strokes or when it stops increasing. You should have two numbers for each cylinder. Then, add a tablespoon of oil to each cylinder & repeat the process, but you only need the final reading for each cylinder.

Write down the results & post back for help figuring out what it all means.

75 Tips

Could it be spark plugs i have never changed them i have only cleaned them?

Check the gap on your plugs,and plug wire connections,look for the simple things first,but also I would check the timing.

(quoted from post at 07:51:06 07/15/16) Could it be spark plugs i have never changed them i have only cleaned them?

Click to expand...

Plugs go bad, replace them before you waste a lot of time chasing the problem.

I would recommend not using champion plugs
I always use Autolite or NGK
does anyone else agree.

I planned on using autolite