GM alternator pulley: Did I screw up buying this??

[G A.]

Re: GM alternator pulley: Did I screw up buying this??

Dan------


Well, I'd say I blew it on the previous post. I just can't figure out how or why I blew it. I'm very sorry if I caused you to buy a part that's not the right one for you.

1969 Corvette with big block and without power steering originally used pulley GM #3846180. That pulley was replaced for SERVICE by the GM #3844100 which is also now discontinued..

Joe, it's not a problem. In fact the '69 3rd ed. TIM&JG says that it is supposed to be a 387 pulley, so it agrees with your original assessment. My concern here is not the $40 for the pulley, but what pulley is in fact proper to have for a non-PS L-71 and what exactly does the little bugger look like.

Grant, I suspect that you feel very confident about the example you have?

[Joe L.]

Re: GM alternator pulley: Did I screw up buying this??

Joe, it's not a problem. In fact the '69 3rd ed. TIM&JG says that it is supposed to be a 387 pulley, so it agrees with your original assessment. My concern here is not the $40 for the pulley, but what pulley is in fact proper to have for a non-PS L-71 and what exactly does the little bugger look like.

Grant, I suspect that you feel very confident about the example you have?

Dan-----


Maybe I was right the first time, but I cannot figure out how I came to the conclusion that the '387' pulley was used for 1969 with L-71. However, I believe the 3829387 and the 3846180 are configured the same EXCEPT for OD. The 3846180 is 3-3/64" OD and the 3829387 is 3-5/8" OD.

[Joe L.]

Re: GM alternator pulley: Did I screw up buying this??

I figure I better give you gentlemen another shot for reference.

Dan------


Now I see part of the problem here. As you suspected (and I incorrectly tried to convince you that you were wrong), this pulley is NOT a GM #3829387. Either it was packaged incorrectly or someone switched it before you got it. The GM #3829387 pulley is as pictured in Wayne's photo and as I have pictured below.

There's no way that you'd get the pulley you've pictured to correctly align with the engine pullies if used for a non power steering big block application.

I strongly suspect that the pulley you have is a GM #3871242 which would be the pulley used for 1969 L-71 with power steering.

[David L.]

Re: GM alternator pulley: Did I screw up buying this??

Dan,

According to my 1969 Chevrolet Parts Catalog (Oct. 1968) the 69 Corvette w/ 427 engine used 4 different alternator pulleys:

69 Corvette (427)(exc. P.S.)
3827387 (3 5/8", W = 13/16")

69 Corvette (427)(C.A.C. w/ H/Per.)(exc. P.S.)
3846180 (3 3/64", W = ???)

69 Corvette (427 w/P.S.)(exc. C.A.C., Sp. H/Per.)
3871242 (3 5/8", W = 1 7/32" measured)

69 Corvette (427 w/P.S. & H/Per.)
3883978 (3 3/64", W = ???)

Pulley # 3844100 (replaced 3846180 in July 1981)
(3 7/32", W = 13/16" measured)

My 1972 Corvette Parts Catalog lists pulley # 3871242 for the 69 Corvette (427) P.S. w/Sp. H/Per. ???????
The 69 Corvette w/H.D. 427 used pulley # 3829387

Dave

[David L.]

Re: GM alternator pulley: Did I screw up buying this??

Here are sketches and dimensions of a 3871242 pulley that I drew back in the 1980's.
The dia. measures about 3 19/32" with a width of about 1 7/32" (total width 1 11/32 at center).

[David L.]

Re: GM alternator pulley: Did I screw up buying this??

There is a copy of a Chevrolet shop drawing of a 3829387 pulley in "The Corvette Restorer" (Vol. 36, No. 2, Winter 2010) on page 23.

3 .625+/-" Dia.
Width = 0.831" to 0.837"
Total Width at center = 0.96"

[G A.]

Re: GM alternator pulley: Did I screw up buying this??

David - Joe - Grant,

Seems these dang P/S pulleys won't leave me alone. Based on the drawings that David provided, the 'critical measurements' of this pulley (total width-3 19/32, total depth- 1 7/32, rear of pulley offset depth- 1/8, groove dimensions 5/8 X 5/8, front inset depth 21/32) match the 242 dimensions. The differences are no 'cast' appearance front or back, no P/N and no inset machining or casting 'inset' on the rear face (this one is completely flat on the rear face, excepting the 1/8th protrusion which I assume gives the correct spacing between the fan and pulley - photo). So it seems I've managed to come up with something I don't need. Guess I need to find another pulley and a buyer now!!

Thanks for the help fellows!!

[Wayne M.]

Re: GM alternator pulley: Did I screw up buying this??

Here are sketches and dimensions of a 3871242 pulley that I drew back in the 1980's.
The dia. measures about 3 19/32" with a width of about 1 7/32" (total width 1 11/32 at center).

Nice drawing. And here's an eBay pic, in an old(er) box, of one a few years ago; went for $155.

[G A.]

Re: GM alternator pulley: Did I screw up buying this??

Nice drawing. And here's an eBay pic, in an old(er) box, of one a few years ago; went for $155.

Maybe the one I have is a re-pop? Or possibly a later GM part without the extra work to machine it to look like the earlier versions?

[David L.]

Re: GM alternator pulley: Did I screw up buying this??

Maybe the one I have is a re-pop? Or possibly a later GM part without the extra work to machine it to look like the earlier versions?

Dan,

GM # 3871242 was discontinued in November 1984 as per GM Parts History and the date on the yellow label on the box is dated 10/30/90. Is there a date on one of the flaps of the box?
Do you now see what I asked the question about the date on the yellow label?

Dave

[G A.]

Re: GM alternator pulley: Did I screw up buying this??

David, the box and sticker both have 3829387 on them. One end flap of the box does have '90' in a circle of numbers, in a light blue ink, the circle has the numbers 4-12 remaining. The numbers 1-3 are missing.

[David L.]

Re: GM alternator pulley: Did I screw up buying this??

David, the box and sticker both have 3829387 on them. One end flap of the box does have '90' in a circle of numbers, in a light blue ink, the circle has the numbers 4-12 remaining. The numbers 1-3 are missing.

Dan,

The box labeled 3829387 was made April 1990. If the pulley appears to be a 3871242 pulley (disc. Nov. 1984) based on the dimensions then I guess we now know that the box and pulley are not a matched pair.

BTW, which of the 4 part numbers mentioned by me in a previous post is the correct pulley for your car?

Dave

[G A.]

Re: GM alternator pulley: Did I screw up buying this??

Dan,

BTW, which of the 4 part numbers mentioned by me in a previous post is the correct pulley for your car?

Dave

David,
The car is an October '69 build L-71 convertible. No power steering. I'm not sure of the 'H.D.' application, L-88?, however based on my knowledge interpreting the listings, I would say the first, 3829387 although it doesn't reference H Perf or SP HPerf. The second listing I think is for a 400HP with air- no P/S. Am I close?

[David L.]

Re: GM alternator pulley: Did I screw up buying this??

Dan,

I am confused as well.

1969 Corvette
427 L36 = H/Per.???
427 3X2 = L71 = Sp. H/Per.???
L68 = ???
427 H.D. = L88 (see 1969 AIM)

I finally found my boxes of alternator pulleys.
I have a used original " 3829387-AI" stamped pulley w/keyway, a NOS (or NORS) 3844100 unstamped pulley w/keyway, an unknown 3 3/8" dia., 0.80" wide (0.93" total width at center) pulley, and many identified stamped steel pulleys of various sizes.

I also found my boxes of alternator fans (several identified variations).

Dave

[G A.]

Re: GM alternator pulley: Did I screw up buying this??

Dan,

I am confused as well.

1969 Corvette
427 L36 = H/Per.???
427 3X2 = L71 = Sp. H/Per.???
L68 = ???
427 H.D. = L88 (see 1969 AIM)

I finally found my boxes of alternator pulleys.
I have a used original " 3829387-AI" stamped pulley w/keyway, a NOS (or NORS) 3844100 unstamped pulley w/keyway, an unknown 3 3/8" dia., 0.80" wide (0.93" total width at center) pulley, and many identified stamped steel pulleys of various sizes.

I also found my boxes of alternator fans (several identified variations).

Dave

If you discover something relevant, I'd like to learn too, if you don't mind.