Need Advise: Flat Spot while Accelerating

[lamaker]

I recently tuned my carbs and adjusted my valves. Upon accelation, there is sometimes (not all the time) flat spots in the pick up. Just seems like something is holding the car back.

I read about this problem before somewhere but cannot remember what causes it.

Any ideas? Thank you in advance.

[WFBowen]

Just for starters, double check your timing advance, especially if you have a vacuum advance distributor. Then, check the accelerator pumps on each carb and make sure that gas is squirted throughout the stroke and that the fuel comes on immediately when the throttle lever is opened. Since you said that it doesn't happen all of the time, I'd lean towards an ignition problem, but it could be fuel starvation. Did it do this before you tuned the car?