Re: Bob's '55 Patrician Blog

Posted by DavidPackard On 2019/1/1 13:32:19

Here is an excerpt from a Carter WCFB Service Manual on the subject of removing throttle valves.

"File off staked ends of throttle valve attaching screws and remove screws and throttle valves from the bores."

Carter most likely marked the valve plates with a 'C' to indicate correct orientation in the carburetor flange. The plates must be returned to the original configuration.
Carter recommends replacement of the throttle valve retaining screws . . . they are a 'use once' item.
Flange and/or shaft wear maybe accommodated by bushings or plating.

I would take the throttle shaft to a local machinist to drill the broken screws. You may have some luck by drilling from the broken head side with a 'right-hand' drill. I would start small and not attempt the correct tap drill size until an effort was made to drive the screw completely through the shaft . . . . meaning, without the head the screw should be able to pass through the shaft as a 'headless' set screw.

I don't know if the 'LocTite' comment was genuine, but if it was there are recommendations on which product to use based on the screw size. If 'red' LocTite was used the assembly must be heated to destroy the locking characteristic of the product. If this is not done the product is stronger than the screw itself and the head will likely sheer in torsion. This heating process should also be done prior to drilling if the fondest hope of driving the screw out with the first drill size is ever going to happen. The LocTite website will have 'time at temperature' recommendations to defeat the locking feature of their products.

I checked a few part numbers for the secondary throttle shaft and found that the Packard part was not unique, in fact the first 'other carburetor' I checked was for a '56 Chevy (Carter 2366S or 2366SA) and it had the same secondary throttle shaft part number. Given the accelerator pedal and transmission linkage, I suspect the primary shaft may become specific to a particular vehicle, but the shaft itself is likely same with a different lever swaged on. Likewise I found the throttle shaft screws seem to be ubiquitous, and are used in many, if not all, WCFBs.

dp