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At what point during 1965 production was the big block engine crossmember added? Was this a running change or did GM start 1965 production with a different style crossmember that would accept the new big block engine. Thanks, Mike
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Your copy of the AIM should answer...
Turn to UPC 2, Sheet one where the basic frame is called out. You'll see the sequence of events by reading the Revision Record block...
Frame was PN 3864676 (as used in 1964) until AIM date 7/24/64 (1964 production was still in effect) and changed to PN 3869753. Whether this version of the frame had provisions for both SB and BB harmonic balancer clearance is unclear...
On AIM date 9/1/64 (only 227 1965's had been built) the frame changed to PN 3871317 and this frame was common to both SB and BB cars although no BB's were factory produced until after the calendar year changed.
Since there was one frame for both SB and BB's and the front cross member was an integral part of the frame, designers anticipated the new big engine coming onstream as early as September 1, 1964... -
Re: 1965 frame with big block crossmember
I have owned two early '65 cars and both have the "divot" in the first cross member to clear the coming big block harmonic balancer. I believe all '65's had it.
Did a body off on a late '64 that had the extra indent but it differed in shape from all others I have observed. If memory serves I think I have seen other '64's with it as well.Comment
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My early (kinda) #014xx has frame depression
And it has its original frame (VIN stampings). So any other cofiguration would have had to be earlier than that.
In reality, the depression is mostly to accomodate the BB crank pulley.Comment
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Re: 1965 frame with big block crossmember
The frame I'm looking to use is stamped with body sequence #109549. This would have frame/car built sometime between January 1965 to February 1965. Should accomodate the big block engine readily. MikeComment
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Re: Your copy of the AIM should answer...
Bear in mind that the dates in the revision record block on the A.I.M. sheets are only the date the sheet was revised in the Drafting Room, and don't reflect the date the change actually occurred in production. The actual production change for any part was handled through a separate NPC (Notice of Production Change) system; NPC's were internal documents, and were not published.
I wrote an article in the Summer, 2001 issue of the "Restorer" that explained the operation of the NPC system and how production changes took place on the line, and a later one in the April, 2006 issue of "Corvette Enthusiast" magazine.
Some changes took place prior to the A.I.M. revision date, and some took place after the A.I.M. revision date.Comment
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Re: Your copy of the AIM should answer...
Note, there is nothing in my post that says what actually happened on the assy line....
Your comment/critique is VERY valid for those novice to reading/interpreting AIM drawings. However, the big picture of what I said remains true:
(1) You can answer some questions yourself by reading the AIM.
(2) There was a frame assy used in 1964 (we know it was SB exclusive in terms of the front cross member).
(3) An 'interim' frame was released at the very end of '64 production that had a short life (essentially through the pilot/initial '65 change over phase).
(4) I don't know the specifics of this frame (heck, it might not have actually been used due to on-hand inventory)....
(5) One PN for the frame ran the balance of the '65 model year, it was used for both SB and BB cars and it pre-dated the release of the L78 BB by a considerable time frame.
Yep, AIM date changes only establish the earliest possible time for a given change to appear. And they don't guarantee when, if ever, a given PN change actually showed up in production....Comment
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You will find the change over is around car
number 990 to 1016. I saw a car around 990 and it had no dent and car 1016 a blue FI conv ( on the cover of Restore awhile back) has the dent. Phil 8063Comment
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