Packard Forum Index » Pre-War (1899-1942)

OK, so here’s the story.
37 Packard 115 C.
Stock carburetor.
I have a constant issue with the air fuel idle mixture screw drifting. This causes over fuel condition, rough running, etc.
In the picture was my fix.
Does anyone have other suggestions on how to keep the needle valve screw from adjusting out.
This usually happens after I’ve driven the car and parked it and let it cool down.
The car started right up at the garage. Ran great until I got about 2 miles from our dinner stop..
When I parked I turned the screw about an eighth of a turn, maybe like a 16th into the lean and the car idle right out.
It ran ok back to the house and then t turned about 1/8 turn lean and it smoothed out , better than the parking lot adjustment.
Thanks

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Wonder if a couple of external tooth star or serrated lockwashers would provide enough grab to keep vibration under control. One at the carb between spring and base and the other at the screw head might bite into the spring and each surface to hold it in position. If that would not work perhaps a small dab of gas resistant glyptal or varnish at the threads would seep in just enough to lock it down but would still "crack" open to allow future adjustment.

What carb are you using,a Stromberg? The way you have the safety wire will tend to open or richen if there is any flexing of the vacuum line,that it is tied to. The original factory carb was CHandler-Groves or later known as Holley.The original factory replacement was WA1 Carter. Even though the C-G carb was said to be bad,I have known two 115C owners who used the C-G carb with no problems.