Just finished putting a new 440 in my 68 satellite with pertronix ignition. It will crank with the key but not fire. If I turn the key on and jump the relay it fires right up. Relay is new.... Any ideas? Thanks!

start circuit isn't complete to the key. check between the relay and key.

Neutral safety wired up and functioning correctly?

He said it cranks but won't fire so it hasn't got any neutral safety switch troubles. It's an ignition switch wiring issue. There are two feeds out of the ignition switch one for start and one for run. In this case the run circuit is fine but no power from the start side. I would check the ballast resister bypass wiring. Ignition 1 circuit.

Maybe the 'start' section of the ballast resistor (if you have one) is bad.

What Stump said: there's an open inbetween the "ign 2" brown wire circuit starting from the ign sw out to the downstream end of the ballast. start with the bulkhead. pull the female terminal off of the "ign" terminal on the starter relay to disable the starter & have a helper hold the key to "start" & with the bulkhead halves seperated see of the rear (firewall) half specific "brown wire" terminal is hot with your meter. On a bare bones '68 it should be easy to pinpoint that brown wire terminal or www.mymopar.com will have a schematic of its location in the bulkhead. I'd say corroded bulkhead terminal(s) or a bad ign switch. if it is the pair of bulkhead terminals I have some NAPA part #'s. holler back with any news.

Ignition switch harness to main wiring harness connector under dash would be my number one suspicion, followed by bulkhead.

I had a ign power wire fail at the ignition switch connector under the dash, tough to find.