backing firingthrough carb

:angry9:

Well I changed out my plug wires and went to start my 70 satellite 383 and there was a popping noise when it was running... so I thought maybe I crossed the wires and lost my mind so decided to start fresh with my service manual firing order diagram... I set the wiring to the firing order per the diagram, with no#1, just left of the bottom clasp that holds the distributor cap down. 1-8-4-3-6-5-7-2,,, I have checked it several times to make sure it was correct.... I have a proform electronic distributor, edelbrock RPM heads/power package, 750 holly double pumper.. I can't imagine that would change the firing order....

So I tried to start it and it pops/back fires though the crab. So I decided to check TDC, timing mark at zero. I checked the rotor and it is pointing to where no#1 spark plug wire is connected to cap.

I can't figure out why is it backfiring through the carb.. prior to the plug wire change, the car was sputter and sluggish.. after running pretty good for about 30 minutes... I figured it was sputter due to the bad wire I found, causing the spark plug threads to be wet.. the other 7 plugs were a greyish in color and dry.

Any ideas of would it could be or what I could check... thnx in advance

Making sure that TDC is on the compression stroke, not the exhaust stroke, right? If nothing else was changed, I'd check that first.

At least it's backfiring out of the carb, and not out of the cigarette lighter or steering wheel... (j/k)

If you have plug wires running side by side they can cause induction and fire a second cylinder so keep the wires apart and if they need to cross keep as close to 90 deg as possible

Remember the dizzy turns at half the speed of the crank, so it's a common trap to put dizzy/wires in 180 degrees out i.e. rotor button points to no. 1 on TDC on exhaust stroke instead of compression stroke. Another common trap is the big block dizzy turns anti-clockwise (where as small block turns clockwise..)
Check the reluctor/pickup clearance in dizzy too with non magnetic feeler guage - needs to be 0.008" clearance max (the less the better, but without contact.)
As BM said, could be cross firing problem - wire separation is the key here.

For what it's worth, when I bought my car it was a dog on the bottom end until about 3000 rpm, when it seemed to clear itself up. Also, it would frequently backfire through the carb on start up. Turns out the timing was set to about 15* retarded and at 2800 rpm the advance would catch up and it would run better. I set the timing to about 18* advanced and it's like a totally different car. Lol, 33* out is a hell of a lot.

Have you tried playing with the timing? Giving it more advance? Are there any vacuum leaks? Does the dist. have a vacuum canister on it and is it good? Try checking the wires with an ohm meter in case 1 is defective. Are the floats in the carb set per Holleys specs? Is it a good strong spark or a weak spark? I know this stuff can drive you crazy so good luck.