carb backfire, help

[jeffs73]

i have a 73 240z and the front carb backfires through the carb only on quick throttle bursts. i've check timing, distributor shaft runout, changed the points, plugs, wires, cap, and rotor. i have not tried rebuilding though. any help is appreciated. thx!

[2ManyZs]

Since only the front one is doing it, it sounds like it might be a "lean pop" caused by the float level being too low. Check and adjust the float level and see if that doesn't cure it.

[LanceM]

Burnt valve??

[jasonparuta]

My triples do the same thing but only about once every time I drive it. I can't tell want it's from either. Any help is appreciated!

[ZmeFly]

99.95% of the time its a lean condition that causes this.

id go with 2many's advice

[beandip]

try this , turn the mixture adjustment clock wise 1/4 turn and see if that helps. I agree sounds like a lean pop.

[240Zdragon72]

My forward carb does the same thing. The only difference is that I can't even get my car to start.....well, it turns over, but dies when I go to the ON position. Does anyone think if I need to buy some damper oil to see if the problem lies with the carbs or the ignition, etc.

Thanks,

Brian:alien:

[jasonparuta]

I finally figured out the my fuel regulator was not giving the proper 3 psi to the webers. books say that you can go between 1.5 and 3 psi. I think I need 3psi due to a radical cam. I bought a pressure gauge from summit and dialed it in. I haven't gotten a "pop" since.

Now I just need to figure out why I get high pressure when I cold start. After I drive it some it goes down to 3psi... weird.