weber backfiring

[1795]

Ted,

I cannot recall from your earlier thread about switching to the Webers, seems to the best of my recollection you had started with the Webers, went to the four barrel and then back to the Webers. Is this correct? Is this the same cam and timing that you had previously with the Webers initially (if my memory is right), or did you change the cam and timing for the four barrel? What is your fuel pressure at. If it is doing this while running lean, that would seem to be odd, unless the cam and the timing are mismatched for the Webers. What is your timing currently?

I am by no means an expert, learning quickly as I go, but my sense is that this is not a jetting issue. Too clean on the plugs could mean that the timing is off and they are getting wet. Even after ten miles they should show some evidence of combustion. Do you have a laser temp gauge? Check the temps on the header tubes while it is running and see if the temps are hot and consistent. If the temps are cool then it might be ignition related. If they are inconsistent, then the cooler ones are not firing all the time, or possibly at all.

Trying to consider all possible scenarios. Good luck.

Jim