bucking and surging at around 2500-3000rpm
I have a 406sbc with nothing but aftermarket parts. In my 84monte it runs high 11's in street trim. When i drive the car around town it has a tendency to buck and surge between 2500and 3000rpm when mainting cruise speed. The car has a 456 gear so that's where most my engine spends most of its time. My HEI dist. has vacuum advance and the canister is hooked up to ported vacuum on the side of the carb. I've heard that depending on what advance springs are in the dist. The ported vacuum could cause it to advance and retard the timing eraticly, also 2900 is right where my advance kicks in. Is this causing the surging or is it the tune on the carburetor. My carb is a 700cfm double pumper, it is jetted pig rich. I know the carburetor is way to small for my motor and when i had a friends 870cfm davinci on it it didn't surge or buck as bad. Any insight would be great.