Anyone know why its doing this?

[us74k5]

I am trying to figure out if the reason my engine is backfiring is because my timing is off. I start driving it, and when i try to shift into second, or start to put it under a load (driving up hill) it backfires. Does not always die, but sometimes it will. Is that just the timing, or could there be another reason?

 

[gopher_6_9]

timing or a very lean condition

 

[Hogback Fabrication]

What fuel and ignition system? I'm assuming this is on a '74

 

[us74k5]

Premium fuel, holey 770cfm truck avenger carb. The carb is almost brand new, ran it on the same engine about 2 months ago, worked great. I am 99.99% certain its not a carb problem. Ignition comes from an MSD HEI ignition. Also had this on the engine when it was in the k20. No problems with it whatsoever, and it also was not damaged at all.

 

[ktmoutfront]

I fought a gremlin like that on an El Camino. Ended up being a broken wire in the ignition loom. Could not see the break. Shielding was OK. Bad manufacturing in the wire. Spent many weeks trying to figure it out. Check your connections.

 

[COCHEV]

backfiring through the carb? did you recently adjust the timing? check easy stuff like cap, rotor, wires etc. or maybe you didn't tighten the destrib back down again then a compression test...

 

[aychdee]

Had that happen in my old '77 small block, cam lobes were damn near completely round. Like said above, check the easy stuff first