AIM Question

[Kevin Whiteley]

For this question, I will utilize specific 68 part number info, but the questions and answers will most likely pertain to all years and parts.

The early BB models used crankshaft pulley #3863108, a cast-iron piece, while later BB's used a stamped pulley #3921923. The AIM lists the latter in the actual drawing (A7 on H345). Why doesn't the drawing or Revision Notes reference the 3863108 pulley? Actually, no where in the entire AIM is the 3863108 pulley mentioned.

I also notice that for this particular drawing the Revision Notes begin at symbol "12", rather than what I would expect to be symbol "1". Why? The Revision Notes do indicate that the entire drawing was revised (Symbol 14) in March 68, which is on the latter side of the model year. Does this mean that the earlier versions of the drawing were in effect "deleted"? And would the earlier pulley (3863108) have been in the earlier drawings?

[Terry M.]

Re: AIM Question

I don't have my 1968 AIM at hand, but I can tell you that the page you reference begins with item 12 in the revision block because there are earlier pages that start with a blank revision block, and go through item 11. In some cases the pages are redrawn along the way, as indicated here.
I am confident, without being able to look, that the earlier pages show pulley 3863108.
Joe Lucia will be able to answer the specific part number question, and probably add to my comments.

[Joe L.]

Re: AIM Question

Kevin------

The reproductions of the AIM's that we all have today are simply a copy of the particular "original copy" of the document that became available once-upon-a-time for reproduction. They are not necessarily complete. Also, bear in mind that the AIM's were a "living document" and were continually revised. In addition, these documents were held by many different folks in the organization. Each of these folks may have been more or less diligent with respect to keeping their copies of the document current and with respect to their own policies as far as retaining older pages. The copy of the AIM that we all have today reflects the revision diligence and page retention policy of the individual that once "owned" this particular "original copy". Everything regarding the AIMs has to be considered in this context.

The particular page that you refer to is the one that happened to exist in the "original copy" of the AIM that was used for reproduction. The revisions indicated by symbols 1 through 11 were on an earlier page. That page was replaced by this page and all of the earlier revisions incorporated into this page without revision notes. Then, beginning with revision #12, the successive revisions were noted and recorded on this page. Apparently, the individual that "owned" this "original copy" chose to discard rather than retain the older pages. That makes a lot of sense, too, from the perspective of the utility of the document. Since all of the revisions had been incorporated into this page, many of the folks that mainrained the original document had no practical use for earlier pages, so they discarded them so they "wouldn't clutter things up" and make it more difficult for them to find the stuff that was really important to them. In an historical context, this is unfortunate, but, believe me, historical context was likely not even on the minds of folks who originally used these documents.

In any event, I'm sure that the GM #3963108 pulley was shown on the page which was discarded.

Also, keep in mind that this pulley is shown in the UPC L-36 section of the AIM. Other 427 engine options didn't necessarily use the same pulley. For the other engine options, the AIM doesn't show the pulley used. It simply says "assembles same as L-36". That doesn't mean that it's the same pulley; it just means that it ASSEMBLES LIKE the L-36 pulley. The AIM says "refer to bill of materials for part number". Unfortunately, we don't have these "bill of materials" today. However, we can sometimes glean the part number information from other reference materials.

[Kevin Whiteley]

Re: AIM Question

Joe and Terry,

Your answers are what I originally suspected, however, it's always good to get a second opinion. I used this particular pulley only for illustrative purposes because it's reference in the AIM shows/displays some of the irregularities in the AIM.

I guess the next question is: Are all of the AIM's from the same "original"? In other words, using 68 for an example only, is the 68 AIM from Mid-America, Ecklers, NCRS Store, etc. all reproduced from the same "original" or does each vendor have their own "original". In essence, if someone buys an AIM from each vendor, will they have more information (if not more paper) than if they buy from only one source.

[Dick W.]

Re: AIM Question

To my knowledge, and I have seen quite a few of them, ALL AIM's are from the same copy. Sadly, but so.

[Terry M.]

Re: AIM Question

I believe Dick speaks the truth. Sad to say the quality of the copies has deteriorated over the years. If you have an early copy it is likely to be better quality than the more recent versions.

[Chris H.]

Re: AIM Question

I bought my 62 AIM from MidAmerica sometime in the lare 80's. I looked at Paragons yesterday and noticed that where I have a 2 page spread of some pages they had them reduced to one page.

Chris

[Dick W.]

Re: AIM Question

I have seen an original AIM for a Vette. Had all the revisions in it. Quite thicker than what is available today. No, I will not reveal what year and who has it.

[Art A.]

Re: AIM Question

Joe, Your assessment of the AIM's revision process is smack on, however I would like to add that in fact the GM procedure called for the person who mainrained an original AIM to DISCARD the old sheet when inserting a new sheet.
And yes all of the vendor reproduced AIM's were from MASTERS that followed this procedure, so they unfortunately don't have ALL of the revisions.

Art