Car surges on freeway driving

Posted by Steve On 2010/4/2 19:40:58

Hello again. This question is about my 1951 Packard 200. Driving performance around town is excellent. When driving on the freeway the car surges mildly, slowly, rhythmically... A slight variation up or down in throttle pressure will cure the surge. Steady throttle pressure is more likely to cause the surge but not every time, nor does uphill steady throttle pressure always create the surge. What I know: Fuel lines clear..Gas filter clean...rebuilt the fuel pump (gas pump diaphragm looked good) Timing and dwell as close as I can make it. Vacuum advance holds vacuum. I am pretty sure it's not an electric problem due to the lack of the sharp instant feeling of a miss or an electrical breakdown. Your input will help me cut back on the Scotch and soda.
Thanks again.
Steve