66 Alternator Probs :-(

[steve styllis]

Hi,

have the following problem on re-assembling a 66 327-300hp car with AC & power steering.

Problem: Alternator belt is too long.

Alternator is # 1100700 (I cant find this part # listed ) dated 6A11 - outside diameter of pulley is 2 3/4" but it does have a very deep groove.

Repro altn. belt bears # 3798498 and is 57 3/4" long.

Balancer pulley diameter is 7" water pump pulley diameter is 6 1/4"

What's wrong here? this is a Z06 belt #302542 - lists 300/350hp 66-67 with AC.

Q. Shouldn't 350hp application use a larger diameter alt. pulley (3 5/8" ) ? Q. AIM lists belt #3861946 - how long is this belt ?

Hope you 66 guys can help. Steve

[Joe L.]

Re: 66 Alternator Probs :-(

Steve----

The 3861946 belt is a 3/8" belt of 54.0" length. However, this belt is correct for non-AC equipped L-79s with N-40. Your car is supposed to use the 3798498 belt which is a 3/8" belt of 57.5" length.

To use the 3798498 alternator belt, your N-40, C-60 car should have the following pullies:

alternator-3846180 water pump-3890419 c/shaft rr-3850838 c/shaft ft-3751232

Nevertheless, if the 3861946 belt will solve your problems(and it appears that it might), by all means, use it.

[Lou R]

Re: 66 Alternator Probs :-(

I had a similar problem with my 66 327/350HP I tried several belts from different vendors and all were too long. I checked the pulleys. They were OK. While at Carlisle I compared the "L" shaped bracket holding the alternator and found mine had been replaced with a later model one. When I installed the correct one the original belts fit. The replacement bracket had a sharper bend than the correct one.

[Jack H.]

Re: 66 Alternator Probs :-(

Joe hits on an important issue that merits further discussion. I had a similar problem with my '71 SB A/C car. Checking GM parts manual (thru '72) against current day GM on-line system vs. claims of various 'correct' cloth wrapped belt repro sources I found a myriad of specs of belt length for the application -- flip a coin on who you believe.

Finally, I bite the bullet and bought a 'correct' cloth wrapped repro belt from one source I trusted. Found it was too long!

Worked with them. Final resolution was tedious and messy but got me there! I pulled and checked each pulley on my car against the list Joe provides. Most all pulleys were wacked with GM # on the back. Found more than one that had somehow 'wandered' during the prior years and put it back to right.

Last, while close now, the alternator was at/near the very end of its adjustment bracket slot. More research. Found SB A/C alt pulley is different from stock base, there are three variations out there in the scrap yards on OD and the ONLY source specing the correct OD I could get my hands on is the '68-69 NCRS Judging Ref Guide!

Rounded up one of these critters, and got closer. Now, I look at the alt adjust bracket itself and find there are several variations that look real similar with modest differences in length and placement of adjust slot. Picked the 'right' one, and BINGO stuff works like El Hoso.

Lesson here: if you're looking for that ONE thing that's wrong, think again. You could well have a cut & paste situation of compound errors over time. Everything has to be right -- trust nothing, verify all!