Quote:
Originally Posted by G.T.O.boy
This car.....has a 683 alt with dual pulley, and dual pulley water pump. Heads and intake are all cast in August/Sept. 63? will have to look when they get back from machine shop.
|
This post is intended to provide some insight into the '64 Model Year Alternator usage. I thought it would be useful to G.T.O.boy after reading his post in the 1964 GTO Tri-power 4 speed registry Sticky Thread. Rather than bury it in that special thread, I thought it was worth revisiting '64 Alternator p/ns. They have been discussed in past threads but I hope to compile the information here as it may help other '64 fans.
O.E. Alternators were produced by Delco complete with the pulley. They carried unique p/ns based on the Alternator model and specific pulley installed. Service Replacement Alternators were produced by Delco without Pulleys (there were some exceptions). By servicing the Alts without a pulley, a single SR Alternator p/n serviced multiple O.E. Alt p/ns. The original pulley had to be swapped onto the SR Alt shaft to complete a repair Alt replacement.
G.T.O.boy, the 1100683 currently in your possession was the O.E. standard release 37A alternator used for the base content (no option) A body. Delco assembled it with a single groove pulley.
At the start of '64 Model Year production on Sept 3, 1963, the 1100676 O.E. 37A alternator was used with PS but without AC in the A body. Delco assembled it with a two groove pulley. The V belt arrangement used with this Alt required a matched twin belt set.
In the big Pontiac, the O.E. standard release 42A alternator used for the base content builds was 1100680. Delco assembled it with a single groove pulley.
At the start of '64 production, the 1100678 O.E. 42A alternator was used with PS but without AC in the B body. Delco assembled it with a two groove pulley. The V belt arrangement used with it employed the same matched twin belt set as used with the 1100676.
Effective on or about Feb 1, PMD announced a revised V belt arrangement for PS cars (both A body and big car) that eliminated the matched twin belt V belt arrangement. The revised arrangement featured a separate V belt to drive the Alt and another V belt that drove the PS pump. The PS pump got a revised single groove pulley as it no longer was driven by a twin belt.
The exact date that the revised PS V belt arrangement entered production is not precisely known. Likely the engineering change allowed for the 1st design twin V belt arrangement and related Alt p/ns to be used up so the date would have varied by Assembly Plant. What is known is that the 1st design twin V belt arrangement and related Alt p/ns were already superseded in the Tempest Inspector's Guide in the revision that compiled all engineering supersedures as of Dec 19, 1963.
At that point, the 1100676 and 1100678 O.E. alternators with the two groove pulley were obsoleted. These alternators when found will have early date codes, not sure I've ever seen one with a 1964 assembly date.
The change allowed Pontiac to use the 1100683 and 1100680 O.E. alternators with single groove pulley for both non-PS and PS without AC in the A body and B body builds respectively.
G.T.O.boy, the two groove pulley on your 1100683 Alternator is not the original pulley.
Nothing prevented the 1100683 Alternator from being swapped to a two groove pulley. My own Nov built '64 has factory PS and was built with the twin V belt setup. I have an 1100683 Alternator with two groove pulley and the repro twin belts in it because I have yet to find a 1100676 core.
Yours may have been converted to a twin V belt setup for racing in an attempt to prevent throwing the belt at high rpm. You might check for a p/n on the water pump pulley. Might show it stamped with a later model p/n which would make it obvious as a swap. Doesn't prove it had a single groove water pump pulley from the factory but would confirm a swap was made.
The standard (no option) car used a single groove Water Pump pulley and a single V belt. PS builds without AC used the two groove Water Pump pulley, both early and late. Only the V belts changed.
All above applies to V8 builds. 6 cyl A body builds used the same 37A alternator as the V8 but because it included a different pulley, it was stamped with O.E. p/n 1100668. The only other alternator used in a 6 cyl was a version of the 55A alternator, with a specific two groove pulley, that was stamped with O.E. p/n 1100665. I won't attempt to cover the 6 cyl applications beyond the O.E. Alternator p/ns.
Back to the V8, the A body with Transistor Ignition and standard steering used the 42A 1100680. Early year with TI and PS, the A body used the 42A 1100678. Late year, it used 1100680 with TI with or without PS.
With AC and TI, the A body used the 60A 1100674 with or without PS. This Alt included a single groove pulley.
With standard ignition and AC, the A body used the 55A 1100627 with or without PS. This Alt included a single groove pulley. This Alt was a carryover p/n as it was also used in '63 Model Year production.
With standard ignition and AC, the big car used the 55A 1100681 with or without PS. This Alt included a single groove pulley. This Alt differed from the 55A 1100627 used in the A body as it had a slightly smaller diameter single groove pulley. It is unknown why PMD engineering decided not to use the same Alt in the A body and big car for this particular application.
With TI and PS without AC, the big car used the 55A 1100682 early year. This Alt included a two groove pulley.
The 1100682 was obsoleted along with the 1100676 and 1100678 after the PS V belt change. This Alt was rare as the application for it was quite limited. I have not documented any builds but it likely would have been specified early year in the A body when TI, PS without AC, and the HD Alternator options were all ordered. It is definitely a rarely seen Alternator as it was obsoleted mid year and early applications for it were also rarely ordered.
After mid year, with TI and PS without AC, the big car used the 55A 1100681 with the single groove pulley.
With TI and AC, the big car used the 60A 1100674 with or without PS. This Alt included a single groove pulley.
Even rarer than the 1100682 might have been the big car special equipment HD Alternator option which got the 62A 1117765. It used a 2 groove pulley and was used with and without PS. It was a unique arrangement and was not affected by the mid year PS V belt change. I don't know when this option was made available. The 62A Alternator was not included in the big car Shop Manual. It was included in the revised big car Electrical Specs that were published in an SCN that replaced the specs shown in the Shop Manual. The V belt arrangement for it was unique in that the Alt was mounted at the RH side.
I think I have covered every possible application, early and late. Let me know if you think I've missed any and I'll look into it.
G.T.O.boy, I'll be curious to learn your cast dates. Aug/Sept castings wouldn't be impossible in a Nov assembled '64 V8 but would be unusual. I only include the block cast date in my engine log so that is the only one important to my records.