truck back fires when shifting 1st to secound.also have to drive with chock on it helps.

Sounds like you need to check ignition timing, then points, plugs, condenser, distributor cap... basic old time tune up stuff.

thank you just got her don't know history but it has upgade Mallory distributer looks new and wires do also pulled one plug looks good?if I leave choke on runs alittle better.thank you 1968 f-100

sorry mis,ment choke on carb.

When the engine backfires, the timing is generally retarded. Since you just got it, make sure the points are gapped properly in the distributor, plugs gapped, then you can set timing. Once you have all of those correct, then you can start tweaking the carb.

thank you, ill let you know how it goes