Re: Bucking Slightly at Cruising Speeds

Posted by DavidPackard On 2024/8/2 19:36:04

Joe I made a significant reduction in similar set of symptoms on my ’48 288 (WDO) by shimming the vacuum piston (aka vacumeter) spring. I left the metering rod adjustment (T109-113) alone and only shimmed the spring with an AN #4 screw flat washer 0.040“ thick, installed in the piston. Somewhere in the mountain of Carter/Packard technical advice I’ve read that spring should be replaced whenever the carb is open for service, however the kits I have bought recently did not include this spring. If that historic advice is well founded perhaps the vacumeter spring takes a set with use, and the mixture will tend to lean with age.
dp