V Belts Came Off When Driving--Questions

[Paul S.]

I was out for a morning cruise in my 67, when what to my wondering eyes should appear--the temperature gauge was pegged all the way to the right. Pulled over, popped the hood and all three belts were off (mine's a power steering, AC, 327/300). Call tow truck and get the car home and head off to the auto parts store for new belts.

My questions--I've been under the hood of this car a lot lately and just finished all my maintenance including checking the belt tension--using the rule of thumb to check for 1/2" deflection--and everything looked good to me. And none of the three belts broke, however the alternator-water pump-crankshaft belt had a nick in it and was twisted around pretty good. Could that have been the start of a break and enough to knock all the belts off?

And it's been a really long time since I've touched belts on any car I've owned--is there something I should inspect/look at aside from the obvious--pulley alignment, anything visibly wrong with the pulley surfaces, ect??

Also, since the AC does not work (hasn't blown cold air for the entire 3 years I've owned the car, is there any downside to not hooking up the AC compressor belt?

Can someone confirm the length for the alternator-water pump-crankshaft belt--NAPA who has guys behind the counter that know something, were out of that belt, and O'Reilly's showed the belt I bought as being for a 327/350 hp excluding power steering, as opposed to my 327/300 hp with power steering and AC. It's Gates XL 7570 13/32" X 57 5/8". Is that the correct belt?

Finally, the power steering pump belt looks like that's going to be a two man operation--any tips on getting that belt tensioned without drafting a helper.

[Al R.]

Re: V Belts Came Off When Driving--Questions

Paul, I'll check the size of the alt belt this PM when I get in. I know I had a hard time getting the right length. May want to check earlier thread by me on this. The power steering belt can be done by you. It requires loosening the bolt underneath the car and the nut on the top side. Pull back on the filler neck with 1 hand or use a pry bar/long screw driver and hold while tightening the top nut. Then crawl back underneath and re-tighten the bottom bolt. Good luck! Al

[Gene M.]

Re: V Belts Came Off When Driving--Questions

Paul,
The correct belt width is 3/8" . Anything wider will not sit down in the groove of the original pulleys. Deep groove pulleys "seat down" the belt better for higher rpm's provided you have the correct 3/8" wide belts.

[Kenneth B.]

Re: V Belts Came Off When Driving--Questions

Paul,
The correct belt width is 3/8" . Anything wider will not sit down in the groove of the original pulleys. Deep groove pulleys "seat down" the belt better for higher rpm's provided you have the correct 3/8" wide belts.

I'm with you unless a pulley is bent or a baring is froze up it's a belt that's too wide as you said.

[Paul S.]

Re: V Belts Came Off When Driving--Questions

Paul, I'll check the size of the alt belt this PM when I get in. I know I had a hard time getting the right length. May want to check earlier thread by me on this. The power steering belt can be done by you. It requires loosening the bolt underneath the car and the nut on the top side. Pull back on the filler neck with 1 hand or use a pry bar/long screw driver and hold while tightening the top nut. Then crawl back underneath and re-tighten the bottom bolt. Good luck! Al

I found your earlier thread here: https://www.forums.ncrs.org/showthre...216#post646216. I may have an aftermarket alternator mounting arm or the existing fan belt has really stretched. The old belt on mine appears to be longer than the 53 1/4" inch belt that you could not stretch tight enough. Right now where my alternator is, I still have roughly an inch left to go tighter and the Gates 7570 replacement belt Oreilly's sold me is 1463 mm long (57.59 inches which the package calls 57 5/8").

The other thing is the belt width--Gates shows it as 10 mm on every belt I've looked at. Depending on part numbers, however the package may show the inches equivalent as 3/8" or 13/32". The power steering pump belt on mine was Gates 7350 and the AC belt was 7530 and both show a width of 10 mm 13/32".

All the existing belts on the car were installed by the former owner and have worked without incident for me for more than 3 years before Sunday. So regarding the comments above on belt width, I'm not sure these days whether the belts are 3/8" as represented on the packages.

I'm going to put the Gates 7570 fan/alternator belt on to see how much adjustment length there is left and go from there--I was hoping this wasn't going to be a trial and error thing, which it appears to be.

Thanks for the input from all.

[Paul S.]

Re: V Belts Came Off When Driving--Questions

Follow up post--I ended up installing a Gates 7530 XL V belt for the fan/alt belt which I bought originally for the AC belt. The 7530 is belt length 1361 mm and belt top width 10 mm. That equates roughly to 53.58" long which seems on par with Al Rains' trial and error. The power steering belt was Gates XL 7350 and 904 mm long and 10 mm belt top width. And I hear you all on 3/8" belt width--as noted in my post earlier, at least with Gates and everything else I see at auto parts stores and online, the belts are 10 mm and you'll see that sometimes described as a 3/8" width but it's probably more properly 13/32". So take your pick.

[Al R.]

Re: V Belts Came Off When Driving--Questions

Paul, I ended up getting a belt from LICS that was 52-5/8 long x3/8 wide. This centered the alternator on the arm. It was for a 64-64 327-350/365HP LICS part # 59-12 or Quanta part # B-036. I'm not sure where the mix-ups are with this belt per the AIM, but I have all the correct pulleys, arms and etc. and the ones listed for this application by GM, LICS, CC and others were too long. Others have had the same problem with this PS AC and alt combo with the 327-300. I did find out 1 thing for sure and that is --there is a wide variance in the lengths of the belts with the same part #. I ordered several from CC, asked them to measure the lengths before sending them out, and still got the wrong length. Finally ordered 1 from LICS, explained what I had been going thru, and asked them for the length I needed. The lady called back later that day and said they had found 1 for me and sent it out. I was beginning to think I would have to make my own. Glad you found 1 that would work for you! Best of luck! Al