Author Topic: 1967 L78 repro Alternator Belt 3849739 fitment problems  (Read 804 times)

jbtech

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1967 L78 repro Alternator Belt 3849739 fitment problems
« on: September 12, 2023, 02:56:22 PM »
I purchased a repro 3849739 alternator belt alternator belt made by Quanta advertised as 55 1/2" in length. When measuring the outside length of the belt it was actually 55". Does this 1/2" really make that much of a difference? I feel like there is no way this belt will fit. I removed the valve cover and pushed the alternator as far as it could go and it's still not close. Am I missing something?

Note: NOM but I'm using correct original GM pulleys
Jose

67 Camaro L78
124377N212598

169INDY

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #1 on: September 12, 2023, 03:14:09 PM »
You could TRY using an impact and Buzz off the ALt Nut and see if with the Belt in the Vee groove can you slide the pulley back onto the Alt shaft, but It sure looks like the Valve cover is NOT going to be able to be reset in place with that Belt.
Jim
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David K

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #2 on: September 12, 2023, 06:54:40 PM »
I assume the number on the belt matches the cover assy it arrived in, and yes, that 1/2" does matter. A local NAPA will have a belt gauge to verify the length. Give Janis a call if they shipped the wrong belt or if it's short. I see the revised chart you showed is from June 67. When was your car built? Let us know what happens. Also, I would have the old belt measured as well. Interestingly the 68 part numbers are different than 67 don't know the length.

jbtech

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #3 on: September 13, 2023, 04:13:43 AM »
Using a combination of Darrell, Bentley, and Jim's advice I did the following to make it work.

- I removed the valve cover and alternator adjustment bolt to move the alternator as close as I could.
- Used an impact gun to remove the alt pulley
- I placed the belt on the pulley and pulled it onto the alternator shaft and installed the nut
- Placed a rag on the alt with a large pry bar
- Removed spark plugs and rotated the engine while simultaneously pulling the pry bar
- Holding pry bar in place while torquing alternator adjustment bolt

The alt is still very close to the valve cover but there is about an 1/8" clearance. The extra 1/2" of belt would have made the process easier. With that said, the belt still has a safe amount of play and I don't feel it's too tight.

 
Jose

67 Camaro L78
124377N212598

cook_dw

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #4 on: September 13, 2023, 11:45:35 AM »
Nice work.  Next update should be of it running..!!..   8)

bcmiller

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #5 on: September 13, 2023, 02:48:49 PM »
That will work for now. Personally I would be looking for a longer belt, you may need it.
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
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x66 714

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #6 on: September 13, 2023, 03:12:30 PM »
I was thinking on my 68 Z/28 I had to put it on the crank 1st. Then the alt & the w/p pulley last, from the back side....Joe
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rich69rs

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #7 on: September 13, 2023, 05:11:58 PM »
……Personally I would be looking for a longer belt, you may need it.

I was thinking exactly the same thing - why not get the correct belt on the car now and be done with it???

Richard
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cook_dw

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #8 on: September 13, 2023, 05:19:56 PM »
If you look at the alt position in relation in the upper bracket it is roughly in the middle of the travel.  The Quanta belts stretch pretty good once ran for several minutes.  He has more than 1/4" movement of the belt when tight so the belt will not damage anything and should be fine and he has room for adjustment for the eventual stretch.  Longer belt will help but over time could run out of adjustment.  Not saying a longer belt is wrong (as I told him that privately) but no really necessary.

jbtech

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #9 on: September 13, 2023, 05:20:49 PM »
I assume the number on the belt matches the cover assy it arrived in, and yes, that 1/2" does matter. A local NAPA will have a belt gauge to verify the length. Give Janis a call if they shipped the wrong belt or if it's short. I see the revised chart you showed is from June 67. When was your car built? Let us know what happens. Also, I would have the old belt measured as well. Interestingly the 68 part numbers are different than 67 don't know the length.

Thanks for the tip. It is the correct belt with part number embossed on the belt just a 1/2" short. My car build date is 04D 4/27/67 to be exact ;)

Nice work.  Next update should be of it running..!!..   8)

Thanks D! Waiting for some small parts to get in, I need to pressure test a couple radiators, work on the dizzy and it should be good to go.

That will work for now. Personally I would be looking for a longer belt, you may need it.

I have a slightly longer belt from a local parts store I'll keep in the car just in case.

I was thinking on my 68 Z/28 I had to put it on the crank 1st. Then the alt & the w/p pulley last, from the back side....Joe

Whatever works I suppose
Jose

67 Camaro L78
124377N212598

Kelley W King

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Re: 1967 L78 repro Alternator Belt 3849739 fitment problems
« Reply #10 on: September 13, 2023, 06:17:36 PM »
Power shift it at 6k a couple times, should fit perfect then.
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