C2 Tach Drive Cables

[Alan Drake]

Are the tach drive cables the same lenght for the FI and non FI cars. The FI distr is about 1 1/2 closer to the fire wall - So did GM make a smaller cable?
Looking for GM part numbers, however my catalog is too new, 53-72.

Have found the following;
57-61 FI w/HL cam 1585653 33 5/8 32 1/2
62 6478121 40 1/4 39 1/2
63 6409130 25 1/8 ?
63-67 6476986 24 1/8 23
?? 6480367 25

Trying to trace the history of the tach cable, not looking to replace mine.

[William C.]

Re: C2 Tach Drive Cables

65 Parts Book gives 1953-55 "6" as # 1582825, 43 11.16 without Casing, 55-57 V8 except FI with High Cam-1569485 shaft 38 5/8 w/o casing, 58 exc FI SHP, 1563139, 66 1/8 w/o casing, 58-59 second design, 1563435, 61 1/8 w/o casing, 53-55 with casing 1582823, (43 1/2), 57-61 with SHP FI, 1585653, cable 33 5/8, casing 32 1/2, '58-61 non SHP, 1588291, cable 61 3/16, casing 60 13/16, 62, (first design) 5656347, w/o casing, 37 1/8, 55-57 exc FI, 5655671 cable 40 1/4, casing 39 1/2, 62 all cable & casing cable 40 1/4, casing 39 1/2, 1963 first design, (all) #6409130, 25 1/8 shaft only, 63-64 second design, #6409507, shaft only 22 1/8, Hope this helps.

[Wayne M.]

My catalogs show '65-67 #3866126 - shaft is ...

23 inches; cable is 24_1/8". This is also the part # shown in the '65 AIM; no exception for L84 in either the parts catalogs or the AIM. This part # and lengths show in July 65, Oct 65 issues of P&A30, and Jan '70 of the P&A30B.

[Alan Drake]

More PN in AIM

Thanks for the info;

Looked in the 64 AIM (pg211)and did find # 3844016 with NPC 294 beside it.
First what is NPC 294? Second, unable to find any change for L84.

And for Wayne, what is the P&A (I known when you tell me I will call myself a name) and is their source of old Parts Catalog, like 53-67 ???

[Wayne M.]

GM Parts and Accessories Catalogs

Alan -- P&A30 was GM's designation for the Parts & Accesories catalogs (or set of catalogs if split into Chassis and Body issues) for Chevrolet Passenger Cars (1938-up) and Corvette (1953-up). [Also included 1st and 2nd series trucks].

I think it was 1969 that Corvette finally got its own, designated P&A30B. It should be mentioned that the P&A30 did NOT cover Corvair, Chevy II, Chevelle or Camaro (they got their own designation, P&A30M.

Thanks to eBay, I have a pile about 3 feet high, covering mostly from '63 through '70. (I'll bet Joe Lucia's is double that). Unfortunately, my earliest Chassis volume is July '65 revision, and that's probably why I can't find Bill C's #6409507 for the '63-64 2nd design cable assy. And probably for the same reason, I can't find the 3844016 that you say is in your '64 AIM. But my '67 (Oct 1, 1966) parts history index [at the back of the '67 Body volume] shows it was replaced in SERVICE on 3-'66 by # 3866126.

As for an explanation of the (written) NPCxxx beside the AIM part #s, I'm guessing it probably means (something) "parts change", and represents the paper trail authorization for the new or revised part. I'll bet Michael H. or John H. would know precisely.

[Mike McKown]

Not disagreeing

just curious why you think the fuelie tach cable should be shorter?

[Alan Drake]

Re: Not disagreeing

Have seen that the Parts Cat had cables listed for FI and non FI cars for early vets, general example say 58-61.
Since the distributor is constructed differently it appears that a cable about 1-2 inches shorter would make some sense, however if the same lenght would work for all models then the factory would use that as a cost savings item.
Cables I have seen while looking for a replacement have not been the correct lenght - looking for a 22 1/8, but finding the 24 1/8. It appears that the second design for 63/64, #6409507, is the correct cable lenght (22 1/8)while I've been finding only the replacement 63-67, #6476986, lenght of 24 1/8.

Now after of these logical reasons (if you accept that statement) - the final motivation -- just because (I've got to stop thinking of things)

Thanks to everyone for input and if more is available please post. Thanks

[Mike McKown]

Re: Not disagreeing

On the earlier models, the FI engine was tach drive off the distributor and the rest drove off the generator which would require a MUCH longer cable.

Comparing an FI distributor side/side with a standard, they look like they would take the same cable length. When I looked in my parts book the other day, I think I remember it showed three different length cables for mid-years, none of them engine specific.

My interest is because I unhooked the cable in my '63 from a standard distributor and then tried to hook it back to an FI distributor after an engine change. The cable is now too long by several inches. I suspect my car has the 24 something inch cable and it needs the 22 something inch. The parts book also mentioned something about cable casing color between the years. Whatever is in my car did not match what the parts book called for. I would suspect someone has changed the cable in my car and had it stuffed back toward the cluster and when I disconnected it, it popped out through the dash panel and now will not willingly go back.

Actually, I can't imagine why one length tach cable wouldn't work for all mid-years regardless of engine, SB or BB.

I was told all the mid-year tach cables were superceded by a different # sometime early on in the Shark era and the originals were no longer available.

[Alan Drake]

Re: Tach Cable Length

Mike
My 64 FI tach cable is 22 1/8 and seems to be GM# 3844016 according to 64 AIM or #6409507 according to 65 Parts Book which are both 22 1/8 inches. Regardless of # it does measure 22 1/8.

Look back at the stuff Wayne Midkiff found. There is also some stuff in past posting by Page Campbell on Jan 9, 05.

If you look to purchase another cable make sure it has the firewall grommet on it. Not sure how one would put it on without pulling cable apart, its metal inside.

[John H.]

Re: More PN in AIM

Alan -

The "NPC" notation in the A.I.M. stands for "Notice of Production Change", which was the document that detailed exactly how a new part change was to be introduced at the plant level, disposition of the old stock, any coordination required with other affected parts, reporting the serial number breakpoint to Engineering, etc. The gory detail of how production changes happened and how the NPC system worked is covered in an article I wrote in the Summer, 2001 issue of the "Restorer", entitled "When Did That Change Shown In The A.I.M. REALLY Happen?".