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!

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.

Burnt valve??

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!

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

id go with 2many's advice

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

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:

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.