454 Chevy engine backfires

Check the coils. We had one go bad and anytime it got hot and I needed power it would backfire and shut us down. I was sure glad when we finally found out what the problem was and got it fixed. Not a problem since.
Ron

Hard one to answer, could be several things from coil, plug, plug wires, distributor, to timing setting.
A little more information about the 454 will help. What year?, Is it carb, TBI, FI, single coil, coil per plug?

Could be something as simple as a distributer cap but we have to know what you have at least what year.

What year? Carb, TBI, PORT inj??? All makes a difference where to look.

Along with the above stuff, check your header bolts.....Dennis

As previous posters state need more info. However, one place to start is wait until it is dark outside, close shades, open doghouse and start engine. Look for sparks around plug wires, distributor, etc. I found the solution to a similar problem with my previous MH this way. In my case it was plug wires putting on quite a light show but could be any of the ignition items.

Change the fuel filter.

1996 fletwood southwind 454 ci rochester TBI, single coil, changed the fuel filter.

Alright, now we know what we are working with. What was the question again? Oh, yea, backfiring under hard acceleration.
Can be one of the following.
1. timing
2. vacuum line
3. distributor springs
4. loose throttle body
5. plugs or plug wires

His dizzy is fully motorized, so no springs. I'm thinking running lean, especially since its only under hard acceleration. Was the tank left full when parked? Are you still running on old gas?