I had my car running for about 5 minutes straight today. Got it running perfect at idle and when I put it into gear it still idled fine. So I take it out on the street and give it about half throttle. It instantly backfires out of the carb and stalls. I figured the timing was maybe 180 degrees so we turned it. Still the same. No matter what the timing is it still does this. It revs perfect in nuetral and will run/accelerate fine under very light throttle.

All of the parts on this car are new except the distributor which makes me pretty sure its the problem. I put a new coil, cap and rotor in it with new plug wires. Does this sound like a screwy distributor or could it be something else?

 

88,

How much advance are you running right now? If you are using the OEM ignition system, remember that you must disconnect the EST bypass before setting the base timing.

 

Is the choke properly adjusted?

 

Could be running too lean, this is the problem when tuning carbs at idle and in the driveway. The only reasons you should have a backfire with engine load is either lean or timing is way off. Good luck, I've had the same problem but it's like once a week and never under the same conditions except it only happens when the engine is warm (go figure). Just the other day my BLMs went to 134 for anything below 2000rpm and the car stalled at a light. I didn't do ANYTHING to the eprom and this stuff keeps on happening, makes me want to go to an alphaN EFI system but I won't do that until I change my fuel pump. Hopefully that's my problem, hope your problem isn't like mine.

 

It is most likely timing related. I am assuming you have a full carb setup with a different distributor. Check the weight/springs. I think the 305 distributor had different advance springs in them.

What's the initial timing & what RPM is the total timing coming in at?

 

The distributor is an old vacuum advance HEI that was givin to me for free. Its pretty rusty inside but I put a MSD coil and accel cap/rotor in it along with a new (melonized steel for the roller cam) gear. The timing was at about 6 BTDC. I didn't do many tests ...after watching flames shoot out of my carb I didn't want go anywhere near it so I didn't go and check things out.

 

Sounds like a lean condition. Check your fuel bowl level. Leave the timing at about 8-10°. That isn't causing your problem though.

 

you have to set the timing with the vacuum line disconnected and plugged, otherwise it is way to advanced and could cause your problems. also make sure your advance system/weights can move freely and that your idle is low enough when setting the timing on these mechanical advance systems.
I figured the timing was maybe 180 degrees so we turned it.
this was a little confusing, did you turn it 180 or just adjust the timing? i'll assume the later because it would back fire a whole lot otherwise. make sure you have the firing order right too.
jess

 

Well I havent had a chance to go and mess with it (cold, no garage, 10 miles away, only around at night) but my dad called me up after messing with it a little. He said that when the car starts the fuel pressure drops to 2-3psi. Its got the stock intank electric pump with a mallory regulator. With the car off and the pump running the fuel pressure stays between 5 1/2-7PSI (guage moves so fast back and forth you can hear it ticking). I'm thinking maybe the filter (placed an inch before the guage) is clogged or something else is clogging up. I have off work tomorrow so I'm going to go there and check it out. Hopefully it is something stupid like that.

 

My 327 did that exact same thing when i got it in there. I could be coming around a corner or off the line at 1/4 throttle spinning the tires, push the pedal to the floor and it would backfire and lose all power. It would only backfire and sputter if i pushed it all the way to the floor. but..It was also sputtering after 4grand in all gears also. I had my timing way outta whack. got a timing light, fixed it an am still running.