How to measure belt length?

Old May 2nd, 2011, 04:45 PM
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Question How to measure belt length?

Moved alternator to other side of motor. Now original belt is too short. What is the most accurate way to measure the belt length around the pulleys? Wire, string, etc.?

Granted the alternator is adjustable so I have room for error but would like to get it close as possible.

Thanks

d1
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Old May 2nd, 2011, 04:59 PM
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I cut a too long used belt and put it around the pulleys and then measure it. This has always worked well for me
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Old May 2nd, 2011, 06:01 PM
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Ok, I'll see what I have laying around. I got plenty of serpentine, but not sure of v-groove.
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Old May 2nd, 2011, 06:09 PM
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I think I am overthinking this...

Since I am mounting the alternator on the driver's side with the bracket and brace for a 1970 Cutlass what part # belt do you all use? I have an A/C (aftermarket) car and instead mounting the alternator to the drivers side, they mounted it under the A/C.

So, I am assuming that the alternator belt goes around the crank pulley and around the fan belt pulley and finally around the alternator pulley (one big oblong circle). If that is correct, then I should be able to order the "factory" belt?

If anyone has a part number, I would appreciate it.

d1
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Old May 2nd, 2011, 07:33 PM
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Originally Posted by defiant1
So, I am assuming that the alternator belt goes around the crank pulley and around the fan belt pulley and finally around the alternator pulley (one big oblong circle). If that is correct, then I should be able to order the "factory" belt?

If anyone has a part number, I would appreciate it.
Here are pics of the driver's-side-alternator belts for a '70 Cutlass...

350:


455:



The GM numbers you're looking for appear to be
391213 without P/S or 406086 with P/S for a 350, or
399628 with or without P/S for a 455.

You should be able to cross reference them in any auto parts store book - Dayco, Gates, etc.
Sizes can be found here:




- Eric
Attached Images
File Type: jpg
1970 350 Belts.jpg (109.4 KB, 76 views)
File Type: jpg
1970 455 Belts.jpg (104.3 KB, 71 views)
File Type: jpg
Alt. Belts by Length.jpg (109.7 KB, 73 views)
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Old May 2nd, 2011, 07:52 PM
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Eric, thanks for taking the time to post this info. I imagine, not only will it help me but others as well.

Shaun
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