1968 SB L79 fan with AC

[Jeff P.]

A4B53888-DCA8-4FE8-8B9A-EFB552ACA8D1.jpgA4B53888-DCA8-4FE8-8B9A-EFB552ACA8D1.jpg
sorry for the double sideways pic.

[Rocco S.]

Re: 1968 SB L79 fan with AC

My 1967 coupe with L79 small block and A/C also has a 7 blade fan with a 1972 date code. The 1967 JM says it shoulkd be a 5-blade fan, 18" in diameter. I'm the second owner. I don't know if the previous owner just upgraded it to improve cooling or there was a dealer recall. I'll be interested in what others say.

Thanks,
Rocco

[Joe L.]

Re: 1968 SB L79 fan with AC

When dismantling my 68 with AC, I noticed It had a 1972 7 blade fan. In the Jm it states most small blocks with ac had 7 blade fans. Was it a supply thing ? Running out of 7 blades and installed 5 blades? It’s a June build. Did they start out with 5 then had heating issues? Lots of questions . SB owners please chime in, I’m adding on to the motor now. Thank you in advance , Jeff. [ATTACH=CONFIG]104390[/ATTACH][ATTACH=CONFIG]104390[/ATTACH]
sorry for the double sideways pic.

Jeff------


All 1968's, regardless of engine or options, were equipped with a 5 blade fan of GM #3888366. The 1972-dated 7 blade fan you have is likely GM #3955182. If so, that fan did not even exist during the 1968 model year.

[Jeff P.]

[David L.]

Re: 1968 SB L79 fan with AC

The GM 3888366 5-blade 17 1/2" dia. fan is stamped "66", "FRONT", "H", and has a 34.5 degree pitch. The fan was made by Hayes-Albion and I believe the "66" is part of the Hayes-Albion part number, not the last 2 digits of the GM part number. The fan was used on 66-67 Corvettes w/427 engines, all 68 Corvettes as mentioned by Joe, and 69-70 Corvettes w/350 engines without A.C. As per Chevrolet Parts History for parts sold over the counter GM # 3888366 was replaced with GM # 3955182 in April 1971. I agree with Joe, you probably have a 3955182 fan.
Dave

[Jeff P.]

Re: 1968 SB L79 fan with AC

Thank you Joe and Dave. Another issue checked off the list.

[Rocco S.]

Re: 1968 SB L79 fan with AC

Jeff,

I don't mean to hijack this post but I thought this would be a good segway to my issue. I knew the 7-blade fan on my '67 L79 w/ A/C was incorrect since it had a 1972 date code. Today, I checked the fan again and it is marked 3931002 K72 and 913894. My brief research on this fan shows that it was used on many Big Block Chevy models starting in 1967 and was then used as a service replacement for C2 models with A/C.

I am trying to correct a few items on the car in preperation for regional flight judging and possible Bow Tie qualifications later this year. I have been looking for a correct, 18", 5-blade fan for some time. The more research I do the more confused I get since many fans don't have part numbers.

On a recent visit to an old-time salvage yard I located what I thought was a correct fan and Schwitzer clutch. The fan is 18" in diameter. The blades measure approx. 3-3/4" wide X 6" long and are mounted to a triangular shaped fan hub with 5 rivets. The rivet heads are flat, not mushroom shaped as per the latest JG. The blade angle was measured as 34.5 degrees. The front of the fan is marked "FRONT" and "H". The back is marked "W" on one of the trianglular arms.

I have attached some photos of the fan. My question is "Will this fan pass flight judging?". It is more correct than the current 7-blade fan. If it means only a few point deduction, I'm OK with that. "Should I keep looking for a used original or buy an aftermarket replacement?"

5 Blade Fan 1.jpg
5 Blade Fan 2.jpg
5 Blade Fan 3.jpg
5 Blade Fan 4.jpg

Thanks, Rocco

[Leif A.]

Re: 1968 SB L79 fan with AC

Rocco,
I believe you have the same fan on your '67 L79 A/C car as I have on mine. David Luikkonen posted some terrific info a while back regarding these fans.

[Tom M.]

Re: 1968 SB L79 fan with AC

Rocco,
The dimensions and rivet configuration of your fan align with the fan on my ‘69 no AC small block.

[David L.]

Re: 1968 SB L79 fan with AC

GM # 3749576 fan: 18" dia., 5 steel blades, 5 dome head rivets per blade, made by Hayes-Albion.
58-63 Chevrolet Pass. w/AC, 61 Chevrolet (348), 61-63 Chevrolet Pass. (327,409).
Dave

[Joe L.]

Re: 1968 SB L79 fan with AC

GM # 3749576 fan: 18" dia., 5 steel blades, 5 dome head rivets per blade, made by Hayes-Albion.
58-63 Chevrolet Pass. w/AC, 61 Chevrolet (348), 61-63 Chevrolet Pass. (327,409).
Dave

Dave------


The blade configuration of the 3749576 is different than that of the fan in Rocco's photo. Also, the center section of the 3749576 appears to have a reinforcement or spacer attached to the center section whereas the fan in Lief's photo does not.

[David L.]

Re: 1968 SB L79 fan with AC

Joe,
You are correct. Over the years I have seen 18" dia. fans like the one in Rocco's photos but never could figure out its application.

According to Chevrolet Parts History for service parts GM # 3749576 was replaced by GM # 3789562 in July 1964 which was then replaced with GM # 3931002 (18" dia., 7 alum. blades with curved tips, 2" pitch). The 3931002 fan was used only on 1968 Chevrolet models w/AC (not Corvette).

Rocco's 18" dia. fan has a pitch of 2 1/8" (or 34.5 degrees). I sold all my 1966-1967 Corvette w/427 fans that were stamped "66", 17.5" dia., 5 blades, 5 flat head rivets/blade with a 2 1/8" pitch. I still have a 3749576 fan (18", 5 blades, 5 dome head rivets/blade) with a pitch that measures 1 5/8". I sold my 3789562 fan which I believe was 18", 5 blades, 4 flat head rivets/blade, and with a 1 5/8" pitch.

Dave

[Rocco S.]

Re: 1968 SB L79 fan with AC

All,

Thanks for the the responses on a very confusing subject. It seems that my 5-blade fan is of the same 18" diameter and configuration used in 1967 except it has flat head rivets instead of round head or mushroom rivets. So I will probably install it for judging since it is "more correct" than the 7-blade unit from 1972.

I might add that when I purchased the fan and clutch from the salvage yard last year it was marked with yellon ink "68 CHEV". Salvage yards usually marked parts this way. I did not mention this in my first post since I did not know for sure if the fan was original to the car it was removed from. I paid a very reasonable price of $40.00 for the fan and clutch.

I can also add that the Schwitzer clutch that was attached to the fan has a stamped date code of 12 9 66. The bearing is very tight but does rotate. It will need to be rebuilt. My car is a late March 67 build date, so the clutch is dated properly.

[David L.]

Re: 1968 SB L79 fan with AC

Rocco,
Does the bolt circle on your fan measure 3" with 2 3/8" hub hole?.......or 3 1/4" with 2 5/8" hub hole?
My 1968 Camaro AIM (UPC K02, Sheet A1) lists 3 fans for A.C. and Z28 options.
3789562 (Hayes-Albion, 18", 3" bolt circle) for A.C. models
3863137 (Schwitzer part # 912239 with date code, 18", 3" bolt circle) for A.C. models
3871276 (Hayes-Albion, 18", 3 1/4" bolt circle) for Z28

My 1968 Chevelle AIM (UPC K02, Sheet A1) only lists GM # 3789562 and 3863137.

If your fan has a 3 1/4" bolt circle it might be GM # 3883159 used on some 1965-1971 Chevrolet trucks.
It also might be GM # 3793882 used on some 1964-1966 Chevrolet trucks.
Dave

[Rocco S.]

Re: 1968 SB L79 fan with AC

Dave,

Thank you for this information. My fan has the 2-3/8" center hole and 3.0" Bolt Circle Diameter. So it looks like it is GM#3789562.

Was this fan ever used on Corvettes? If yes, what year and application?

I will still install it on my 1967 replacing the 7-blade fan for judging. I'll take a few points deduction for originality.