Lack of power in 4th

[farmer]

I found the final post where the member updated us after finding and fixing the issue...sorry I cant find the whole posting list on it but I remember it was very similiar to what you report...just to give you a hint...this is from November 9, 1998...waaaaay back in the old days...

His experience is very similar to mine, right down to running out of fuel!

I spent some time studying the points Friday, they haven't been contacting squarely but the looks of it, but the spring tension seems plenty. I replaced the components a year or 2 ago, and the new spring is riveted to the point arm.

I checked out the spare distributor in the motor I just bought, older style spring and arm, very loose tension, which give me some hope for that motor if needed.

I installed the pertronix Friday night and test started it, ran great until it ran out of gas. I plan on pulling the tank, so I didn't refill it. Saturday I got the boat fuel tank out of one of my project trucks, and threw it on the M715, which should help rule out a fueling concern I had as well. Disconnected the vacuum advance, and set the timing to 5* reconnected the vacuum advance and tuned the carb to be happy. Sounds pretty good, I just haven't had a chance to road test. I've been doing my research on vacuum advance being hooked to manifold vacuum and believe I have it set correctly for that, so I'll try it. If not, then I'll disconnect the vacuum advance and try without.

[Nailhead]

His experience is very similar to mine, right down to running out of fuel!

I spent some time studying the points Friday, they haven't been contacting squarely but the looks of it, but the spring tension seems plenty. I replaced the components a year or 2 ago, and the new spring is riveted to the point arm.

I checked out the spare distributor in the motor I just bought, older style spring and arm, very loose tension, which give me some hope for that motor if needed.

I installed the pertronix Friday night and test started it, ran great until it ran out of gas. I plan on pulling the tank, so I didn't refill it. Saturday I got the boat fuel tank out of one of my project trucks, and threw it on the M715, which should help rule out a fueling concern I had as well. Disconnected the vacuum advance, and set the timing to 5* reconnected the vacuum advance and tuned the carb to be happy. Sounds pretty good, I just haven't had a chance to road test. I've been doing my research on vacuum advance being hooked to manifold vacuum and believe I have it set correctly for that, so I'll try it. If not, then I'll disconnect the vacuum advance and try without.

I tried mine without, and it didn't like it very much: it would stumble when I stepped on the throttle. VA hooked up eliminated that.

[farmer]

To muddy the water even more I pulled out a vacuum gauge and attempted to diagnose the engine problems and set the timing via vacuum.

Truck warmed up, vacuum advance disconnected, timing right at 5 degrees I had around 11" hg, though it was fluttering. Loosened the distributor and advanced it til it read 16-17" hg and retarded to 15-16" hg, still fluttering. Snap the throttle it dives to 0, recovers to 20, and levels out back 15-16. Supposedly that means rings are shot. Checked the timing with a light, and without timing marks it looked to be at least 20-30 degrees, which seems absurd.

Finally test drove it like that, after hooking up the vacuum advance. Still struggling up a slight grade to maintain 30 mph. Ran about 5 mph faster downgrade. Could be too much advance with the VA hooked back up. I want to try the vacuum timing with the VA hooked up.

Talking to a friend of mine about what the vacuum gauge was telling me, he asked about the PCV. Mine isn't hooked up, just open. He told me to fix that and try again.

[Nailhead]

To muddy the water even more I pulled out a vacuum gauge and attempted to diagnose the engine problems and set the timing via vacuum.

Truck warmed up, vacuum advance disconnected, timing right at 5 degrees I had around 11" hg, though it was fluttering. Loosened the distributor and advanced it til it read 16-17" hg and retarded to 15-16" hg, still fluttering. Snap the throttle it dives to 0, recovers to 20, and levels out back 15-16. Supposedly that means rings are shot. Checked the timing with a light, and without timing marks it looked to be at least 20-30 degrees, which seems absurd.

Finally test drove it like that, after hooking up the vacuum advance. Still struggling up a slight grade to maintain 30 mph. Ran about 5 mph faster downgrade. Could be too much advance with the VA hooked back up. I want to try the vacuum timing with the VA hooked up.

Talking to a friend of mine about what the vacuum gauge was telling me, he asked about the PCV. Mine isn't hooked up, just open. He told me to fix that and try again.

Hang in there, you'll get it-- just keep your eyes open & don't disregard any clues, or make any assumptions. If I had kept this in mind, my truck wouldn't have spent last winter dead in my yard.