Misfire?
 

Just installed a new cam and lifters into a chevy 383. Upon accelerations, a popping sound from the right headers. Doesn't occur during idle, and doesn't occur at speed, and doesn't occur when reving the engine in neutral or park - only when applying a load. Very conscientious about adjusting valves and following in structions. Spark plug wiring correct. Electrical? Readjust valve lash?

The secondary side of the ignition should be checked over closely.

The valve adjustment is always a suspect when this happens, as well.

If the heads are new or have newly machined seats and valves, this may be the culprit. This will sometimes go away w/time. You should do a compression test if the ignition passes muster.

Agreed.

Are the springs up to par? How many miles did you have on the original valvetrain?