[Bob McLaughlin]

First place I'd look is setting the valves with the engine running , by the book , one bank at a time . Sounds for all the world like you've got an intake valve off its seat , wanting a proper adjustment . Barring that , you could maybe check your firing order before you get oil all over the place ; two plug wires mixed up would sure give you that "popping" sound . Bob

 

[Bob McLaughlin]

SUSPENSE.....wait for it.....

You will let us know what the cause is , won't you ? The suspense is killing me ; too many years as a mobile mechanic . You can fix them in your sleep if you have accurate symptoms . Bob