Packard Forum Index » Post-War (1946-54)

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

All together a different engine, but I had that annoying attribute with my 56 Caribbean for several years and also I thought it was an improperly functioning vacuum advance. Easy enough to check semiquantitatively if you have a hand vacuum pump and a timing light.

What ultimately solved it for me was increasing the carb main jet size a couple of thousands. The change made no measureable difference in the gas mileage. Carb float level might also be a good candidate to check out.

Right on Owen!!!! Now that I think of it, when I rebuilt the carb the kit had a "new design" needle and seat that was installed with a certain stack of fiber washers under the seat. When I drove the car it couldn't get out of its own way. After messing and fussing with the carb, talking to the supplier, I put the old needle and seat back in and had to re-adjust the float. It ran fine, didn't stall in a tight turn, no hesitation on acceleration........however it was months before I took the car on the freeway and have not connected the possibility you suggest (float level) until you stated it in your post. Gawd, I love this forum..Thank you Owen. I'll keep you posted.

Regards, Steve......

I agree with Owen--the surging is caused by a lean condition. I have encountered this on several cars now that the plague of ethanol is widespread.

You are lucky in that your carb has metering rods that are very easily set. The procedure is in the shop manual, and can be done with the carb on the car in only a few minutes. Try putting it to standard condition first in case they are adjusted wrong. If you still get surging, then just set the metering rods a little higher at a time until the surging is gone. In an extreme case you would need richer (thinner) metering rods, but I'll bet you won't.

Hi Ross thanks to you and Owen for the tips. I am going to return to the carb and try the metering rod adjustment first, then if needed I'll take the top off and re-check the float adjustment. But first, I think I need another scotch and soda.
Regards, Steve.....

The Toyota dealer might put a metal plate on the underside of your gas pedal and call it fixed for you.