Willys flat top four dead miss on #1

[portajon]

Thanks for the forum, already got some good advice on an M274A mule here. Any help with this old Willys would be appreciated. Flat top four, think it is a 1952 or there about.

This engine runs about as well as one can, with a dead miss on #1. Pulled the plug, not fouled or wet. Firing with a good spark and checked compression to 75 lbs, which seemed to be in the same ball park as #2. It appears to be a lack of fuel, but can't figure out why. We pulled the valve cover next and confirmed everything looks intact there.

Any ideas? Thanks for your input in advance.

 

[NDT]

It can happen that a plug will fire outside the hole but not with compression. Make sure you are using copper wire spark plug wires, swap the plugs between 1 and 4 and see if that fixes it. 1&2 share the same intake port, so fuel issues sound unlikely.

 

[portajon]

It can happen that a plug will fire outside the hole but not with compression. Make sure you are using copper wire spark plug wires, swap the plugs between 1 and 4 and see if that fixes it. 1&2 share the same intake port, so fuel issues sound unlikely.

This is interesting. Neighbor that is pretty good mechanic said same thing. We swapped plugs between 1 & 2 and the misfire stayed on #1. But still may pick up a new set of plugs. Any reason you suggest swapping 1 & 4?

 

[NDT]

Any reason you suggest swapping 1 & 4?

Nope. Could swap any, but you already did, so that rules out the plug itself.

 

[portajon]

Engine runs pretty darn good on 3.... just lacks some power and sounds like a Harley at idle. I was concerned about compression, as #1 showed only 75lbs. But then we checked #2 and it showed only about 60lbs. I lost faith in the gauge at that point, as I think 90lbs is normally considered the low range for a cylinder to fire.

Neighbor is now determined to figure it out... he is old school heavy equipment guy and doesn't understand what is going on with this little engine... he called an old partner of his about it who suggested maybe the head gasket is blown between #1 & #2 , causing the weird pressur3es and operatrion....

We will keep digging into it. Thanks for the input and if anything else comes to mind, please let me hear from you.

 

[just me]

Waking the dead. You figure it out yet?

 

[portajon]

Waking the dead. You figure it out yet?

Nope. Won't know until next season when I tear it down. I am betting on a burned exhaust valve. I have driven it all over the ranch here, routinely take it up to elevation on some of the roughest back country trails you ever saw. Does a commendable job at 75% power. Fuel mileage is awful though.

I leave this ranch, in east Oregon, next Friday and get on my way to the Hawaii ranch. Boss really had to twist my arm to get me to go work in Hawaii for the winter.

 

[just me]

You could determine the issue by running a cylinder leakdown test before you dismantle it.