Alternator Brace identification help please: 1967 L79 with C60 but NO power steering

[Scott S.]

1967 coupe, L79 with C60, manual brakes, no N40

I'm not sure what alternator brace this option combination is supposed to have, and I'm not sure what I actually have now. The previous owner (1972-1976) removed the C60 components from the engine bay to save weight and horsepower for drag-racing in the early 70s, but included all of the main original parts (e.g., A6 compressor & brackets, Blower & Evaporator box assembly, condenser) with the car in boxes. I'm not sure about parts like the alternator brace though.

The receipt file shows that a lower alternator bracket (GM 3846565) was purchased in December of 1976. Since that brace was part of the engine assembly, it's not listed separately in the AIM. Is 3846565 correct for this application?

The Alternator TOP brace that I have is pictured below. I'm not sure how to measure it properly, but wrapping a tape-measure around the curve for the longest overall dimension from end to end is roughly 16-1/4", and the slot is roughly 4-1/4" long. It is stamped with a "B" and also has what looks like a checkered or diamond stamping in the metal along the length.

Is there enough info here for a positive ID?

[David L.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

I would say you need brace # 3881816 (my photo on left, total slot length = 4 1/2", stamped "B", the manufacturer) which was used on 1966-1967 Corvettes w/SHP 327 (exc. P.S.) as per my 1967 Chevrolet Parts Catalog. It appears that you have a 3881816 brace but the bottom end looks like it was cut off square. It also looks like the area around the slot was flattened. Is the measurement from the CENTER of the end of the slot to the CENTER of the hole 13 1/2" as shown in my photo on the left? The total length of the slot on your braces appear 4 1/2" long. A drafting scale does not get the job done in this case.

I have also enclosed a photo of a 3884640 brace (photo on right, total slot length = 3 5/8") used on 1966-1967 Corvettes (327)(exc. SHP), 1966-1967 Corvettes (327) w/SHP, P/S, and A.C., 1968-1969 Corvettes (exc. 427).

I have about 40 more other braces in my 30-year collection.

Dave

[Scott S.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Dave, thanks for the reply and the pictures. I measured my alternator brace as shown in your picture, and the length from the center of the end of the slot to the center of the hole at the far opposite end is 12-7/8". Measuring the straight-line distance from the center point of one end of the slot to the center point of the other end of the slot = 4-3/8".

The 1967 AIM shows that the 327/300 uses the 3884640 (UPC 6-A2, Item 10), while the air conditioning section for the 327 engine calls out 3854028 (UPC C60-C2, Item 2). I looked up both in the parts book, along with 3881816:


3884640
(1966-67) Corvette (327) (exe. Sp. H/Per.),
(1966-67) Corvette w/Sp. H/Per. (P/S w/C.A.C.) (327) ....... 12-37/64" long, 3-5/32" slot, 17/64" offset, curved


3854028
(1964-65) Corvette w/Air Cond. (exc. Sp. H/Per. Sp. H/Per. w/hyd. lifters) ....... 12-1/16” long, 2-7/32” slot, 1/4” offset, curved


3881816
(1966-67) Corvette w/Sp. H/Per. (327) (exc. P/S) ....... 12-31/32" long, 4-7/64" slot, 17/64" offset, curved


What I’m looking for is the “1966-67 Corvette Sp. H/Per. (w/C.A.C) (exc. P/S) (327) .......”, but I don’t see any alternator brace part number that is configured for this RPO combination (L79 with C60, no N40).

It is an unusual combination of options.

[David L.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

First of all your brace looks like it has been modified at the bottom end. It should look like photo below on left. Does the hole look original (centered on the brace)?

The photo in the middle is from my 1967 Chevrolet Parts Catalog (page was revised May 1967).

I believe that the correct brace for your car is PROBABLY GM # 3881816 (1966-1967 Corvette w/SHP (327)(exc. P/S) but I am NOT 100% sure at this point in time.

The length of the slot on my 3881816 brace measures 4 1/2" (end to end) but about 4 1/8" (4.12"+/-) on the ARC from the center of the half circle of one end of the slot to the center of the half circle on the other end (see photo at right). The parts catalog list 4 7/64" (4.11"). This measurement check out.
I do not know how the 12 31/32" length was determined in the parts catalog.

What pulleys are on your car? Are they deep groove pulley? The water pump pulley and the crank pulley usually have part numbers stamped on them. What is the diameter of the alternator pulley? There may or may not be a stamped part number.

According to my 1967 Chevrolet parts catalog the water pump pulley for a 67 Corvette (327) w/S.H.P. & A.C. (exc. P.S.) is GM # 3848904 (6 9/32" O.D.). I could not find any crank pulley or alternator pulley specifically for your options.

Dave

[Scott S.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

First of all your brace looks like it has been modified at the bottom end. It should look like photo below on left. Does the hole look original (centered on the brace)?

The photo in the middle is from my 1967 Chevrolet Parts Catalog (page was revised May 1967).

I believe that the correct brace for your car is PROBABLY GM # 3881816 (1966-1967 Corvette w/SHP (327)(exc. P/S) but I am NOT 100% sure at this point in time.

The length of the slot on my 3881816 brace measures 4 1/2" (end to end) but about 4 1/8" (4.12"+/-) on the ARC from the center of the half circle of one end of the slot to the center of the half circle on the other end (see photo at right). The parts catalog list 4 7/64" (4.11"). This measurement check out.
I do not know how the 12 31/32" length was determined in the parts catalog.

What pulleys are on your car? Are they deep groove pulley? The water pump pulley and the crank pulley usually have part numbers stamped on them. What is the diameter of the alternator pulley? There may or may not be a stamped part number.

Dave

Crankshaft Pulley:3858533 BJ (2 x deep groove)
Water Pump Pulley: 3848904 CS (2 x deep groove)

A6 Air Compressor/pulley is date-correct original

[Scott S.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

A few more pictures of the ends.

[David L.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

Your alternator brace definitely has been cut at the bottom end for clearance purposes i assume. I will check and see if I have any braces that are the same as yours.

Your 3848904 W/P pulley is correct for your 1967 327 SHP w/AC (exc. P/S) as per my 67 parts catalog.

Your 3858533 C/S pulley is correct for a 1967 327 SHP (exc. P/S) . I assume with or without A.C. as well.

Is the alternator pulley a 3 3/8" Ford pulley or a 3 3/8" GM pulley? Is the pulley part of the fan or are the fan and pulley two separate pieces?

Dave

[David L.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

According to my 1967 Chevrolet parts catalog the following fan belts are used by 66-67 Corvette 327 w/SHP & AC (exc. P/S):

GM # 3847702 (3/8"-52 1/2"), alternator & W/P pulleys

GM # 3847705 (13/32"-57 1/2"), AC comp. pulley & W/P pulleys

[David L.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

The alternator pulley for your 1967 is shown in the 1967 Corvette AIM (C60, sheet C2), GM # 3846180 (w/RPO 79).

The 3846180 is described in my 1967 parts catalog as 3 3/64" O.D. w/ 1/2" groove width.

Dave

[Scott S.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Is the alternator pulley a 3 3/8" Ford pulley or a 3 3/8" GM pulley? Is the pulley part of the fan or are the fan and pulley two separate pieces?

Dave

Dave,

The old generic (incorrect) service replacement alternator had a Ford pulley. The correct rebuilt alternator I received from John came with a pulley (no number stamped on it) and my notes at the time said that it should be 3-3/8" diameter. I checked my pictures and the tape measure shows about 3-3/32" but the true center of the pulley is under the tape measure. Another picture shows my caliper measurement at 3-13/64".

As you said, the '67 AIM shows alternator pulley GM 3846180 for the L79, and the parts book shows that GM 3846180 should be 3-3/64":

3846180
64-65 CORVETTE (C.A.C. w/Sp. H/Per.) (327),
66-67 CORVETTE w/C.A.C. (427) (exc. P/S) .......... No fan .......... 3-3/64" OD .......... 43/64" shaft .......... 1/2" groove width


The 1966 JG has detailed pulley information (p. 138), and shows the following for L79 with AC:

L79 ..... 350 ..... Air Cond. (C60) ..... 3-3/8" ..... 1/2" ..... 3846180


The 1968-69 JG (p. 54) shows BOTH measurements, depending on the year:

1968 ..... 390/400 ..... C60 only ..... 3-3/8" dia ..... 3846180 ..... thin
1969 ..... 390/400 ..... C60 only ..... 3-3/64" dia ..... 3846180 ..... thin

[Scott S.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

According to my 1967 Chevrolet parts catalog the following fan belts are used by 66-67 Corvette 327 w/SHP & AC (exc. P/S):

GM # 3847702 (3/8"-52 1/2"), alternator & W/P pulleys

GM # 3847705 (13/32"-57 1/2"), AC comp. pulley & W/P pulleys

Thank you also for checking the belt numbers. I have read in the archives that the Quanta belts for my options (L79, C60, no N40) in 1967 are incorrect, and from what I recall, it's due to confusion over the correct pulleys (and sizes), which was only recently resolved (last year) in favor of the deep groove pulleys for this specific set of options. I think Quanta is basing their suggested belts on the regular groove pulleys that would be correct if the car also had power steering in addition to C60 with the L79 engine.

I will cross that bridge when I get to it

[David L.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

I believe that your pulley is GM # 3844100. It may be NOS or it may be a reproduction. I have a NOS 3844100 pulley and it measures 3.198" dia. which would be 3 13/64".

GM # 3846180 (3.04" dia.) was replaced by GM # 3844100 (3.20" dia.) in July 1981.

I also have a used original pulley that measures 3.10" O.D. that has been replated that I bought at Corvette Carlisle about 1987 or 1988. Photos are posted below. I always thought that it was a 3846180 pulley but it is 0.06" to big in diameter according to the parts catalogs.

Dave

[Scott S.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

I believe that your pulley is GM # 3844100. It may be NOS or it may be a reproduction. I have a NOS 3844100 pulley and it measures 3.198" dia. which would be 3 13/64".

GM # 3846180 (3.04" dia.) was replaced by GM # 3844100 (3.20" dia.) in July 1981.

Dave,

That might explain why both measurements are given in the 1968-69 JG, one was the measurement of an original 3846180 and the other was the measurement of the 3844100 service replacement. I will keep an eye out for a correct 3846180. I'm sure the 3844100 works fine, but now that I know what the right part actually is, there's no reason not to try to find one. Glad we discussed this, and thanks very much for the assistance.

Regarding the alternator brace, it seems as though the correct brace must be one of the following:

3884640
(1966-67) Corvette (327) (exc. Sp. H/Per.),
(1966-67) Corvette w/Sp. H/Per. (P/S w/C.A.C.) (327) ....... 12-37/64" long, 3-5/32" slot, 17/64" offset, curved

3854028

3881816
(1966-67) Corvette w/Sp. H/Per. (327) (exc. P/S) ....... 12-31/32" long, 4-7/64" slot, 17/64" offset, curved

If I knew which one was correct, I could begin the hunt. I have only found a handful of examples of the L79 with C60 and no N40, but the differences in length and offset between the three braces are so slight that it might be difficult to differentiate one from another without removing the alternator brace from the engine for measurement. The length of the slot might be easier distinguish while mounted on the engine. Basically, it's either a 2" slot, a 3" slot or a 4" slot.

[David L.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

The 3854028 brace on a 1965 Corvette bolts on to the intake manifold with bolt # 180129, not the upper water pump bolt.

Also, the 65 Corvette w/SHP & AC uses brace # 3846862 which also bolts to the intake manifold. Refer to the 1965 AIM (UPC C60, sheet C2).

Your 1967 brace bolts up to the upper water pump bolt (1967 AIM, UPC C60, sheet C2).

My educated guess for the correct brace for your 67 w/SHP & AC is still GM # 3881816.

After you get your engine assembled I am 95% sure that the 3881816 brace will bolt up correctly with the alternator bolt located approximately in the middle of the slot assuming you have all the other correct components (pulleys, fan belt, etc.).

Dave

[David L.]

Re: Alternator Brace identification help please: 1967 L79 with C60 but NO power steer

Scott,

I have a total of 48 alternator/generator braces in my collection as shown in photo on left. I have many duplicates and as many as 9 of just one brace. The photo on the right shows just 6 different Corvette alternator braces.

Dave