'65-67 BB vs. SB frames .... (Michael H)

[Wayne M.]

Same topic as '63 frame stencil location thread below, but different questions, following MH's mention that only one frame # was used per model year.

What procedure was used to differentiate the big block frames with the rear stabilizer mounting nuts (spot welded internally, during frame manufacture). Was there a separate pile of these frames outside in the yard ? Did they have a different part # or suffix ? I would think that AO Smith would have had an interest in controlling inventory of each type, and that St.Louis would also want to feed the correct frame into the chassis line, especially if destined for a 396/427 [wouldn't matter if it ended up on a 327 car].

This subject was touched upon a few years ago, but never completely resolved, to my satisfaction.

[Stephen L.]

Re: '65-67 BB vs. SB frames .... (Michael H)

The '67 AIM only calls out 1 frame for both body styles. Then on UPC 2 A1 the additional bracket for convertibles is called out as an additional weldment completed at St Louis.

Observing that preassembled assemblies used in the car such as the differential or engine are not broken down to individual components, gears, pistons etc. I would have to believe that the frames were all made the same for BB and SB, by the frame manufacturer, and the only modification was for the convertible mounts.

[John H.]

Re: '65-67 BB vs. SB frames .... (Michael H)

The A.I.M. would seem to confirm that the weld nuts were present in all frames. If you look at the "Non-Illustrated Parts" sheet in the L-78 section in the '65 A.I.M., there's no entry for UPC 2 (Frame), which says there was no unique part number required for an L-78 frame. The same is true in the '67 A.I.M. on the same sheet for the L-36 option (which was the controlling option for release of BB-unique parts) - no unique frame part number required for a BB in '67 either.

My '67 small-block has the weld nuts for the rear stabilizer bar brackets.

[Joe L.]

Re: '65-67 BB vs. SB frames .... (Michael H)

Wayne------

Part of the confusion here might relate to previous discussion of frame differences involving later model years. For the 63-67 period, I don't see why there would have needed to be frame part number differences (except, possibly, for 1965), but there could be other reasons that frame part numbers changed during a particular model year. However, I don't find too much evidence of that having occurred. Here's what I find were the frame part numbers, PRODUCTION and SERVICE, for 1963-67:

1963----------------GM #3819263

1964-----(early)----GM #3843361
1964-----(late)-----GM #3864676

1965----(early)-----GM #3863627
1965-----(late)-----GM #3871317

1966----------------GM #3871317

1967----------------GM #3900200

There MAY even have been other part numbers for frames used during the 63-67 period. However, these are the only ones I've been able to verify. That absolutely does not mean that there were not others. It just means that there were, AT LEAST, these.

I have never, personally, verified that any 1965-67 Corvette frame was manufactured without the weld-nuts for the rear stabilizer bar. However, I would not rule out the possibility for the 3863627. I expect that it did have the nuts, but I can't rule out that it didn't.

For 1968 and later, things changed. There were, at least, 2 frames for any given model year through 1978. That's, of course, because the frames for auto trans and manual trans applications were different through 1978.

Although no difference, or inference of a difference, is shown in any 68-74 AIM for big block versus small block frame nor is any difference shown in any 1968-74 P&A Catalog (not surprising in the latter case since if there had been different part numbers for weld-nut and non-weld nut frames used in PRODUCTION, there's no way that GM would have SERVICED the non weld-nut frames), I am absolutely certain that, at least for 1969, such a difference existed for some or all of the model year. The frame on my small block did not have provisions for the rear stabilizer bar weld nuts. I have made a mini-study of other 1969 Corvettes with small blocks and some of these did not have the weld nuts, either. Some did. In any event, there had to be a difference in frame part number for those with and without weld nuts.

[Philip C.]

The only difference I know on the 65

Frames are the frame bump for the big block damper was added about car 1000. That 65 FI cover car 1,016 has the bump car 980 something did not. Later in the year about mid way the seat belt cable center bracket changed these may have changed the part number.I also dont know about weld-nuts. Phil 8063

[Michael H.]

Re: '65-67 BB vs. SB frames .... (Michael H)

Wayne,

As others have mentioned, the frames for any of the C2 years, or part of the year, would have been the same part number. The cost involved in having two separate frames shipped from Smith would have well exceeded the cost of adding the labor/material for the sway bar to all frames, for a number of reasons.

The bean counters at GM always figure out the most cost effective way to handle these things. It may have cost $0.50 to add the hardware to each frame but the cost of the second part number in the system would have probably exceded that figure. I once read a memo from headquarters (GM) on the actual cost of a single part number in the system and I was absolutely amazed. I don't remember the number all these years later but it was substantial.