A few things to look for-

  Leaky plug wires- easily found after dark, probably not the issue at 2k-3.5k rpm

  Carbon tracking in distributor cap, rotor shorting out to dizzy shaft.

  Loose or cracked spark plug or insulator porcelain missing or cracked. These usually miss/pop under load, regardless of rpm. (more likely)

  Possible carb issue at transition, from primaries to secondaries. (less likely)

  Valvetrain issue- flat lobe(s), bent pushrod(s), burnt/bent valve (less likely)

Thats all I got

Dan'l

In a weekend, my buddy and I slapped a 350 together for a boat.

On Sunday afternoon, we were ready to to fire it up. Fired up pretty easy, but had a stumble in it.

Ended up going to the river on that Tuesday. Had stumble in it the entire time at the river, wtf...

Started doing a compression check on the 1,3,5,7 side all OK

The 2,4,6,8 side plugs were all HAND TIGHT at best. My buddy did that side plugs...

Stumble went away, lol

Dan'l


I found a plug that was cracked completely in half. Had to be a faulty plug. Thanks everyone

New plug wires don't mean there good. Was it fine before you burnt you other wires?  Prefab or built wires.


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