'72 fan belt help needed

[R N.]

Hello All,

Working on a '72 SB, AC, PS, and I'm having trouble finding the correct length for the alternator belt. The existing belt is 55" long but it rubs on the PS pump.

In the GM techincal specifications the data tells me the belt should be 52.75" but all the other data I see says the belt length with AC should be 54.25".

55" is too long, so I can't see the 54.25" working, the 52.75" should be short enough to clear the PS pump, but I really would like to know what is the correct length for the alternator belt with AC & PS.

If it helps, the PS belt on the car is 36.5" and the AC belt is 58".

As always, thanks you for the help.

[Joe L.]

Re: '72 fan belt help needed

Hello All,

Working on a '72 SB, AC, PS, and I'm having trouble finding the correct length for the alternator belt. The existing belt is 55" long but it rubs on the PS pump.

In the GM techincal specifications the data tells me the belt should be 52.75" but all the other data I see says the belt length with AC should be 54.25".

55" is too long, so I can't see the 54.25" working, the 52.75" should be short enough to clear the PS pump, but I really would like to know what is the correct length for the alternator belt with AC & PS.

If it helps, the PS belt on the car is 36.5" and the AC belt is 58".

As always, thanks you for the help.

Kurt----

GM says that the original belt was GM #3959166. However, that belt was never available in SERVICE and I do not have specs on it.

The original SERVICE belt for the application was GM #3861946. This belt is a 3/8" X 54.0" belt.

Caveat: I have found that belts that GM says were used in PRODUCTION for some applications were not the ones actually used in PRODUCTION. I have also found that some of the belts that GM cataloged as the correct SERVICE belt for an application do not fit correctly. The alternator belt is the one that most commonly falls into these categories.

[R N.]

Re: '72 fan belt help needed

Thank you Joe.