bad plugs?

[ReBeL]

ok well back at it was woundring if any one has any thoughts.

put the new carb on the bronco had 2 plugs fauld out so pulled and cleand them up put back in ran it stared to time it and adjust the new carb to the moter. was running for a bit then went down hill fast rechecked and I got 4 fauld plugs only 1 of the same plugs as the first time.
so here is my list of questions.
1. what make it back fire through the carb
2.what makes it back fire through the exuast (carb and exuest at the same time also)
3.what makes it faul plugs
4.could it be a electionic model that is on the iner fender giveing me all the greeff

oh this is on my 78 bronco with the 400

[poorboy1]

timing could be way off. is it HEI or points dist.

[85blazer4sd]

sounds like too big of carb on it, also way off timing. Causing it to over fuel I noticed that in wilsionville evry time it would bog down from getting too much gas.Hope that helps

[ReBeL]

it is electic it does not have points


well at the mud bog I had a 625 eldbrock and now I got I bleave a 750 but it is on what ford calls the 400 big block

[BigMack]

400's don't like that big off a carb unless the motor has been modifed from stock.

[Outlawford]

sounds like timing or your carb is to much 4 motor.