1934 Packard 1100 - Backfire and stumble at 50MPH
Posted by Christopher Slater On 2020/5/10 0:08:45
Drove my 1934 Packard 1100 Standard Eight with a stock (but rebuilt) carburator on the highway today. As I approached 50MPH I could feel the car start to hesitate as if it was losing power. As I pressed the accelerator to increase speed past 50MPH the car started bucking and backfired.
As soon as I slowed down below 50MPH the car behaved normally again. I left the highway and for the next 20 minutes the car continued to drive strongly under 45MPH which is its normal behavior. It idles well with an infrequent light paff but again that's been normal for all the time I've owned the car. The car starts easily, even after sitting in the garage for a couple of weeks, idles smoothly and warms up without issue.
After this behavior on the highway I experimented with the throttle around town. I noticed that in any gear as I increase the throttle past 2/3rds throttle, and the engine RPMs increase towards the higher end of the RPM range, the power drops, the engine power seems to hesitate, and it doesn't seem to breath correctly as if its being held back. I am very gentle with this car and cannot be accused of racing the engine in any gear. I should be able to drive the car faster than 50MPH on the highway with its stock 3-speed transmission and non-highway gears, correct? I know it should not be bucking.
Anyone have ideas for diagnosing the source of this hesitation and the associated lack of power at 2/3rds throttle?
Attach file:
(266.11 KB)
As soon as I slowed down below 50MPH the car behaved normally again. I left the highway and for the next 20 minutes the car continued to drive strongly under 45MPH which is its normal behavior. It idles well with an infrequent light paff but again that's been normal for all the time I've owned the car. The car starts easily, even after sitting in the garage for a couple of weeks, idles smoothly and warms up without issue.
After this behavior on the highway I experimented with the throttle around town. I noticed that in any gear as I increase the throttle past 2/3rds throttle, and the engine RPMs increase towards the higher end of the RPM range, the power drops, the engine power seems to hesitate, and it doesn't seem to breath correctly as if its being held back. I am very gentle with this car and cannot be accused of racing the engine in any gear. I should be able to drive the car faster than 50MPH on the highway with its stock 3-speed transmission and non-highway gears, correct? I know it should not be bucking.
Anyone have ideas for diagnosing the source of this hesitation and the associated lack of power at 2/3rds throttle?
Attach file:
(266.11 KB)
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=222223