Strange Miss

[Dragon]

The other day I was running okay ans suddenly the truck started shaking bad. It dropped a cylinder. When cold it is okay after about 3 minutes it gets sick. 3 month old wires, plugs yesterday, Accel Points eliminator 2 years Accel Super Stock coil and dizzy cap.

Any suggestions money is limited. P.S. My top end got noisy on a long trip and has stayed that way since. Great oil pressure and 135 lbs compression +- 7 lbs.

P.S. O'reilly parts suck 2 starters 5 PS Pumps Every brake part premature failure. All in one year from the big O.

P.s.s. The truck shakes bad, real bad with the miss and gets worse the more throttle it gets.

[70_F100]

Sounds like you've done your homework.

Did you check the compression with the engine hot or cold? If cold, check it hot, you may have a bad/broken compression ring.

Put a vacuum gauge on it. You should have 17-18 inches of vacuum at idle. Fluctuation would indicate a vacuum leak (intake gasket, brake booster, pcv, etc.)

Is the choke coming all the way off? Is all of the choke linkage working freely? If it's an automatic choke, it should start opening after a couple of minutes of running. If it stays fully or partially closed, it would cause a flooding/over-rich situation that would result in poor performance/rough running. If it's electric, make sure the wire is connected and getting power. If it's manual, make sure the cable is working freely and opening and closing the choke properly.

Is there any smoke coming from the exhaust? White smoke would indicate coolant in the cylinders. Black smoke, overfueling. Blue smoke, oil.

Isolate the dead cylinder and check the plug wire with an ohmmeter. If you don't have one, just switch the plug wire with one that is good, and see if the miss/skip follows the wire. Just because they are new, doesn't mean they aren't bad (see your comments about O'Reilly's). Same for the cap, rotor and other ignition components.

What did the plugs look like when you pulled them? Did one or more of them look any worse than the others?

You say the top end is noisy. Do you know why? Bent pushrods, worn rocker shaft, worn rocker arm, etc. can do funny things. As the engine heats up, the oil thins out, could be one or more lifters collapsing.

Check all of these things and report back.

I'm sure there's at least one of us who can help you diagnose it.

[Dragon]

Worn rocker shaft and one weak tappet but it has been that way for a while without the miss. I will look more after I get paid money is tight.

[Dragon]

The miss was the driveshaft tearing out the yoke. Made for a real rhythmic vibration that felt like a hard miss.