Supercharger Crank Pulley Difference?

[61Lark]

Why did Studebaker change the part number between the 57-58 Golden Hawk pulley and the 63 Lark/Hawk pulley? I have a crank pulley that has both part numbers, 535843 and 1557958, stamped on it. Is there an difference between the two?

[S2Deluxe]

Why did Studebaker change the part number between the 57-58 Golden Hawk pulley and the 63 Lark/Hawk pulley? I have a crank pulley that has both part numbers, 535843 and 1557958, stamped on it. Is there an difference between the two?

Those #s appear to be in the casting and not stamped? That certainly arouses my curiosity. I have a VS-57 set up that I bought from a collector in Vancouver WA., who told me it came off a '58 J body Packard parts car he had. The pulley has only the earlier number cast in. Your pulley having both #s would have to've been produced later. My guess would be, that the only real difference was the addition of the later # to the casting and the color used to paint them? Studebaker may have decided not to remove the old part # from the casting because the part could still be used for the earlier applications as well? All I know is they were at least painted different colors!

Mark

[61Lark]

The numbers are stamped, it can be hard to tell from the pictures. My guess is an old pulley was pulled from inventory and stamped with the new part number. I don't know if it was modified at the same time or not.

I hadn't thought about the paint color. We do use different part numbers for the same part in different colors at work so that could be a possible explanation.

[nels]

The 57 pulley is larger diameter than the two that were uses in 63 and 64 Hawk Lark type. The 63 and 64 pulleys also have a pilot diameter that fits into the harmonic balancer.

[martincl]

The 57 pulley is larger diameter than the two that were uses in 63 and 64 Hawk Lark type. The 63 and 64 pulleys also have a pilot diameter that fits into the harmonic balancer.

My VS-57 crank pulleys are the same OD as the one in my 63 R2 Hawk; 7 3/4". My 64 R2 Hawk has a smaller pulley at 7". This all seems to agree with the chassis parts books as the R2 pulley changed part way through the 63 model year. The casting numbers on these pulleys appear to be the same as the numbers in the books.
There also appears to be different 63 and 64 S/C pulleys; 1557956 & 1560405 respectively. All my Paxton blowers have the same pulley! Can anyone tell me the difference between these two parts? I assume it's the pulley OD.
Thanks.

[61Lark]

The 57 pulley is larger diameter than the two that were uses in 63 and 64 Hawk Lark type. The 63 and 64 pulleys also have a pilot diameter that fits into the harmonic balancer.

Thank you! I found a picture of the later pulley today and saw the pilot for the harmonic balancer.

Nick