Balance hose was torn
 

74 260Z
balance hose was torn on the backside

I replaced that and backed off on the low speed idle screw, and a hair on the high speed idle screw,
I will replace the hose on the anti backfire valve
and equalize the carbs
then the engine will be in good shape

No more back fire and accelerates through the whole rpm range now:D

cool

only took a week to get the motor running good
I will finish the brakes this weekend
and finish the clutch hydraulics
then I take a test drive

Rick, what was your exact problem? i think i have the same one...

.cre

The car was backfiring through the front carb
the rpm were drifting bigtime several hundred RPM
it would not go past 2000 RPM and would just barely idle

check your hoses esp the balance (or crossover hose) the one from the rear carb to the mixture screw at the front carb)

and ensure you have good damping oil in the carbs

I have it balanced pretty good by ear now and when she warms up evrything seems well (but this is no load)

I will reinstall the fuel tank Thursday and see how she works under load Providing I get the Clutch Master cylinder in today