Was the #621 used on early '66 Corvette Big Blocks?
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Re: Bellhousing #621
I have only seen the 444 on 66 bigblock cars...John -
Re: Bellhousing #621
John and Michael-----
Yes, all 1966 Corvette big blocks used the GM casting #3872444. Very early 1967 Corvettes may have used it as well.
The 3899621 was used for most, if not all, of 1967 for all big blocks except L-88. It was also used for all 68-74 big block applications except 68-69 L-88/ZL-1.
From a FUNCTIONAL perspective, the 3872444 and the 3899621 are equivalent and may be interchanged for all Corvette applications originally using either. The 3899621 superceded the 3972444 for SERVICE.In Appreciation of John HinckleyComment
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Re: Bellhousing #621
Joe,
I once heard that the '621 bell housing was not used on L-88's and ZL-1's.
For the ZL-1 Camaro's, I have heard that they used the 3858403 bell housing.
Why was this the case? Was the same SB bell housing also used for the L-88's?
I have always wondered why GM would use the SB bell housing for these special
BB engines. Obviously, it had to have something to do with a smaller clutch
assembly ( weight ? ). I believe the SB used a 10.40 clutch while the BB used
an 11.00 clutch.
SteveComment
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Re: Bellhousing #621
Steve-----
Yes, as I mentioned in my previous response, the 3899621 was not used for L-88 or ZL-1. The GM #3858403 was used for all L-88 and ZL-1, including those ZL-1's installed in Camaros. It was also used for most, if not all, 1965 Corvettes with L-78 (the GM #3840383 MAY also have been used for some of these. It's identical to the 3858403 except for a feature irrelevant in a Corvette application).
The GM #3858403 is not a "small block bellhousing". It was used for a lot of small blocks, but there is nothing that "ties it" to those engines. It's simply a bellhousing designed for use with Chevrolet block bolt pattern, small block or big block, and 12-3/4" flywheel size.
The 1967-69 L-88 as well as 1965 Corvette with L-78 were the only Corvette big block applications which ever used a 12-3/4" flywheel. However, since they did use that size flywheel, they also used the GM #3858403 (or, 3840383) bellhousing which were the only available bellhousings in the GM "parts bin" designed for the intended application.In Appreciation of John HinckleyComment
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