casting # part# id

[Bill W.]

I have a bell housing with the casting # 3858403 this # is a cast # not the part # .what does it fit ? I also have a water pump pulley with the # 3947824BV stamped on it any ideas ? Bill

[Joe L.]

Re: casting # part# id

Bill-----

In this particular case, the casting and part numbers are one-and-the-same; GM #3858403. This bellhousing is designed for use with 12-3/4" flywheels and 10-1/2" clutches. It was used on most 1964-68 Corvette small blocks, 1965 L-78, 1967-69 L-88, and 1970-72 ZR-1. It was also used on MANY other Chevrolet cars in the 60s. It is completely interchangeable with bellhousing GM #3840383. The only difference is the presence of drilled and tapped bosse(s) on the upper side(s) of the '403'. These bosses are not used in the Corvette chassis application.

Pulley GM #3947824 was used for 1969 full size Chevrolets with 427 special hi-performance engines. It was discontinued in March, 1970. Since this pulley is designed for use with the "long snout" type waterpumps, it has no Corvette application.

[Bill W.]

Re: casting # part# id

Thanks Joe. I have the 383 and the 403 .I didnt notice the missing boss until you pointed it out.Is there anything you dont know ?I work at a Chevy dealer & our parts dept.has a hard time looking up bumpers for a silverado . let alone old parts. thanks again. Bill

[Joe L.]

Re: casting # part# id

Bill-----

The interesting thing is that some 403s have the upper boss on the left side only and some have it on both sides. On those with it on both sides, some have the right side boss drilled and tapped and some don't.

[Bill W.]

Re: casting # part# id

mine has the boss on both sides with only one drilled. do you think one of these was a service part ? the 383 must have been big block only .Bill

[Joe L.]

Re: casting # part# id

Bill------

I don't know if the configuration which you have was just SERVICE or not. I expect that it was used in PRODUCTION, though. The fact that any 403s with the bosses were used on Corvettes always has surprised me. These were totally uneccessary in the Corvette application and meant that these bellhousings had to receive at least 2 additional machining operations that were totally unneeded. At the same time, the 383s were available. So, I don't know why the 383s were not used for all Corvette applications.

As far as 383 bellhousing application goes, they were not used exclusively for big blocks. They are seen sporadically and randomly during 1964-65, as I recall.