Alan, first sorry to here of the headache. The method that I have sucessfully used when in doubt about a timing problem is, Take the spark plugs out. put your finger over the number one cylinder
(Front cylinder) have some one slowly bump the engine over until you get compression. On this compression stroke make sure the piston is all the way to the top (Feel screwdriver) then be sure the rotor button is pointing right at number one spark plug wire post, in the distributor. Double check that the firing order of the wires, are they in the correct places? Make sure it is correct with the way the distributor turns when cranking.
Again be sure you are wiring it the way the rotor turns when you crank it. If all this is done, it is in time. The backfire has always been a secondary ignition problem for me , not other stuff. Hope this Helps....Chb46
