1967 L79 Alternator Belt

[Mark S.]

I have checked the archives extensively and have not been able to solve my problem. My alt/water pump belt is too short.

My 1967 L79 has Power Steering and does NOT have A/C. I bought the correct replacement belt GM3861946 for the alternator/water pump which measures 54" long. I called Quanta and I was told that this is the correct belt.

My car is all stock with correct exhaust manifolds and alt brackets. The crank pulley is 3858533, the water pump pulley is 3770245 and the alternator pulley is 3829387.

I put a tape measure around the pulleys with the alt in its mid point travel and measured 56".

I have no current plans for judging but I would like the car as correct as possible. Any advice would be greatly appreciated.

Thank You,
Mark

[Greg T.]

Re: 1967 L79 Alternator Belt

Had the same problem from Quanta. Same set up for a 66 L79. They sent me another and it fit fine. They may have some shorter ones still in stock. Ask for a replacement.

[Paul D.]

Re: 1967 L79 Alternator Belt

I purchased a Quanta p/s and alt belt 3 years ago and did not have any problems. Fitment of alt was in the middle of the bracket range...P...

[Larry M.]

Re: 1967 L79 Alternator Belt

Mark:

I also had problems getting the correct length Quanta belts for my 1967 327/350 HP car with factory air conditioning (but no other power options). What their book said did not work....either to short or to long. But they worked with me to gets ones that did fit correctly, although the part numbers were different.

To get the correct lengths, I bought cheap generic belts of the correct widths that were longer than needed and cut them. I then positioned the air conditioning compressor and the alternator on the short side of their adjustment ranges (to allow for new belt stretch) and wrapped the cut belts over the pulleys until the ends matched....marked the exact position.....and then removed and measured the belts. That is the installed lengths I supplied Quanta to get my replacements. A bit of a hassle, but you only need to do it once.

Larry

[Mark S.]

Re: 1967 L79 Alternator Belt

Thank you for all of your suggestions. I will give Quanta a call and see if they will work with me.

Larry, I have an old belt that is too short. I could cut it open and use it for a template to get a better idea of the proper length.

It does bother me that I can't figure out why the correct belt is too short. The only way that I can get the belt on is by removing the top alt adjustment bolt.

[Larry M.]

Re: 1967 L79 Alternator Belt

Mark:

In my case, I "learned" from Quanta that they actually had TWO AC belts with the same primary part number and each one was a different length. One was "A" and the other was "B". But their catalog didn't show this, only the primary number. Apparently they did this to help a number of folks who had fitment problems but wanted the "correct" part number. May have been related to the AC compressor clutch diameter(s) for original versus some of the replacement compressors. Not sure.

I found that I needed the "B" version. Also found that the proper length alternator belt I needed was listed for the 1964-65 SHP w/AC. I own a 1967 SHP w/AC. Go figure! Maybe on March 28, 1967,(my car build date) the factory guys found a few old pulleys and/or mounting arms laying around in the parts bin that they decided to install on the car. Or maybe one of the early owners made some changes ?? (probably more likely). Although car has only 26,000 miles from new.

But now I have the proper numbers if I ever need to re-order......just hope they (Quanta) don't make any additional changes.

Larry

[Bill I.]

Re: 1967 L79 Alternator Belt

Larry, how about that, my build date is the same. Bill.

[Mark S.]

Re: 1967 L79 Alternator Belt

Thank You again. I will try to get a more accurate belt measurement and then give Quanta a call.

[Kurt B.]

Re: 1967 L79 Alternator Belt

Don't forget to allow for the belt to stretch after it has been installed for a while.
Kurt

[William P.]

Re: 1967 L79 Alternator Belt

Here is my experience with the same problem.

If you are purchasing a Quanta belt, they are very tight when new. After a few miles they loosen up quite a bit. Loosen and disconnect your alternator from the upper bracket to get the belt on, then you should be able to reconnect the alternator to the bracket. Drive a few miles and adjust for tension. I do not know if this makes up for two inches but be careful getting an exact size you need because after use they will loosen.

Mine actually loosened so much after a few miles that the fan was not turning much and I almost overheated. I called Quanta and they said this was normal that is why they put a claimer to recheck tension after a few miles. My alternator is now adjusted near the back end of the bracket.

Good Luck!

[Henry S.]

Re: 1967 L79 Alternator Belt

There was a thread last year about the 327/300, no PS or AC and the same problem. Belts guys had gotten from Quantra for that application was also wrong. Tried to use the belt they sent for mine and the alternator was right up against the valve cover, no adjustment. I ended up getting a longer belt.

[Mark S.]

Re: 1967 L79 Alternator Belt

Today I put my old 1970's era "Gates Extra Service 8449" belt on and it fits fine (55" long). The old Gates belt is beat up and doesn't look pretty but it may last another 20 years. That should give me enough time to figure out what to do with my 54" long Quanta belt.

Thank you for all of your advice!

[Joe L.]

Re: 1967 L79 Alternator Belt

I have checked the archives extensively and have not been able to solve my problem. My alt/water pump belt is too short.

My 1967 L79 has Power Steering and does NOT have A/C. I bought the correct replacement belt GM3861946 for the alternator/water pump which measures 54" long. I called Quanta and I was told that this is the correct belt.

My car is all stock with correct exhaust manifolds and alt brackets. The crank pulley is 3858533, the water pump pulley is 3770245 and the alternator pulley is 3829387.

I put a tape measure around the pulleys with the alt in its mid point travel and measured 56".

I have no current plans for judging but I would like the car as correct as possible. Any advice would be greatly appreciated.

Thank You,
Mark

Mark-----


GM #3861946 is a belt of 3/8" X 54" and it's the belt that GM SAYS was the one originally used for your application. However, the question remains as to whether it's the one that was ACTUALLY used. In the vast, vast majority of the cases, the part that GM SAYS was used is the part that was ACTUALLY used. However, in the case of these belts, I'm not so sure.

In several cases over the years, I have found that the alternator belt that GM SAYS was used for an application ends up being too short. Since there are so few cars around that still have their original belts, it's very hard to determine, with certainty, what belt was ACTUALLY used. This "phenomenon" is not just true of reproduction belts. I have found this to be true even when GM belts of the ORIGINAL GM PART NUMBERS WERE STILL AVAILABLE. I have come to the following conclusions:

1) the belts that were ACTUALLY used were different than the ones that GM SAYS were used. It is VERY possible that current day conclusions as to what are the "correct" belts are based upon what GM SAYS were used rather than on observations of cars with original belts (since, as I say, such cars are extremely rare); OR

2) the manufacturing conventions used to determine the lengths of the original belts were different than those used later, including today's reproduction belts.

I think the suggestion that has been made with respect to Quanta's having available reproduction belts of the same embossed part number but of different lengths is your best way out of this "dilemma" if you want to have the "original" part number on the belts. This, of course, assumes that they have such availability for the particular belt you want.

Otherwise, I'd use a reproduction belt of 55" (GM #3843162) or 56" (GM #3882814) and let it go at that. Those are likely the part numbers of the belt that would have been used if the belt that GM SAYS was used was not actually used.

[Mark S.]

Re: 1967 L79 Alternator Belt

Joe,

Thank you very much for your advice. I really appreciate it.

Mark

[Mark S.]

Re: 1967 L79 Alternator Belt

I wanted to provide an update to my alt belt saga.