66 L79 belt question. How many?

[Brian G.]

Hello all,
I need a consensus on how many belts the 66 327-350 car should have with no power and no air. JM states there should be 2 grooves in each pulley.
It also appears that 327 (without regard to hp) would then have 1 (alternator) belt only.

Quanta sells 2 belts orig GM part 3861946 for alternator and a water pump belt GM part 3837810, possibly referred to as an "idler belt". This second belt is on the outside groove closest to radiator side and goes vertically down to outside groove on the other.

My car has both of these belts. If you say only one belt, the obvious question is: What is the other belt doing besides going round and round? Should the radiator side grooves be belt free?

Some have said they have seen both 1 belt and 2 like this. What do you think?

Thanks, Brian

[Joe L.]

Re: 66 L79 belt question. How many?

Brian-----

TWO belts. The inner belt, referred to as the water pump belt, is a CAPTIVE belt that goes between only the waterpump and balancer pullies. The outer belt, referred to as the alternator belt, goes between the alternator, balancer, and waterpump pullies.

By the way, if you add power steering to the car, you get rid of the captive belt. The inner pulley then drives the alternator and waterpump; the outer pulley drives the power steering pump and waterpump (requires change of alternator pulley).

Getting rid of the captive belt is just ONE of the many good reasons for adding power steering.

[Gary B.]

Re: 66 L79 belt question. How many?

Brian,

My '66 L79 had two belts when i bought it about 9 yeras ago, but if you have your car judged with two belts you will get a deduct. I'll bet money on it. To date, attempts to convince the team leaders that two belts is correct have proven fruitless. So, you will see '66 L79 cars with one belt, but I bet it's because someone removed the captive belt in order not to get a deduct. I talked with just such a person at the 2002 National. He took off the 2nd belt because the JG said 1 belt was correct. I haven't heard anything to lead me to believe that a change in the JG will ever happen. Frustrating, but true.

Gary

[Joe L.]

Re: 66 L79 belt question. How many?

Gary------

Well, it's hard to imagine that anyone would be able to determine years after the cars were built if they were actually built with one belt or two on the basis of observation of "original" cars. I mean, even if you found a low mileage, apparently very original car, the fact that a belt was ABSENT would not, necessarily, say that the car was always that way.

What we do know is this:

1) If there was never a belt there, folks in the past would be unlikely to ADD a belt. In other words, if they didn't take a belt off, they'd be unlikely to put one back on;

2) GM rarely built cars with "unused" pullies. Unused pullies infer to a buyer that looks under the hood that "something is missing". Of course, this might also instigate a dealer to add a belt when a customer later complained. However, there were a few instances in which there actually were unused pullies, but in most of those cases, there won't be an unused pulley on BOTH the balancer and waterpump pulley;

3) GM says that two belts were used for 1966 Corvettes with L-79 and w/o N-40 and w/o C-60. Since they built the cars, their say-so must be given some credibility. These were as follows:

waterpump (groove 1)----GM #3837810---3/8 X 34-13/32" The reason for this special length belt is that this is a CAPTIVE belt and the belt length must be exact to fit properly;

alternator (groove 2)----GM #3861946---3/8 X 54"

[Brian G.]

Joe....

Joe, Thanks for your reply.
Are you saying that the correct configuration is: belt closest to engine block is captive and goes vertically between waterpump and balancer AND the other belt, radiator side goes between those two and alternator?
Block side 2 pulleys only, radiator side 2 pulleys plus alternator?

Thanks, Brian

[Jim S.]

66 SB Water Pump Pulley Grooves

Brian
I purchased my 66 L79 38 years ago and it had the captive belt as Joe describes. I have no reason to believe it was added before I bought the car.

When I added PS from a wrecked 69 sm in 1970, I just added the single pulley to the crank and had a belt from the crank to the PS pump. So now it has the original captive belt and alternator belt along with the added third PS belt.

Michael Hansen has previoulsy posted a photo of the L79 engine being intalled to the frame during assembly at the factory showing the captive belt already installed. Perhaps you can get him to repost it over at vetteheads.com where he currently resides. I think the photo is also in Noland Adams book.

Jim

[Gary B.]

Joe, where does GM say "two belts were used"? *NM*

[Gary B.]

Jim, yes, but...

Jim,

The photo you mentioned is indeed in Noland's book. But there is an issue with that photo in terms of which groove the belt is in in the photo and which groove the captive belt is in on real functional cars.

Gary

[Chuck S.]

I Don't Know Jack About C2 Corvettes...

But, I do know from being around in January, 1966, that all Chevrolets began to be equipped with seat belts at all seating positions (well, two front and two back on a full size sedan)...it was a Federal mandate or something. You also got back-up lights as standard equipment.

For a JM to say a 66 should unconditionally have only have one seat belt without some VIN number break around January, 1966, would be really getting on thin ice if you ask me. JMHO

[Gary B.]

Chuck; we're talking V belts, not seat belts. *NM*

[Gary B.]

No one would add a belt...

Joe,

I agree with you 100% that no sane person would consider adding a captive belt unless there was one there to begin with. The only issue is how can we come up with evidence to convince the '66 and '67 revision teams to changes the '66 and '67 JGs. That is where I'm stuck and where things have been stuck for going on 5 years according to my records on this topic.

Gary

[Wayne M.]

Plant Photo from Noland's Vol 2

for your consideration. I vote that captive belt is in groove closest to block.

Used Adobe Photoshop to darken highlights, de-screen, bump up the contrast and crop (the hand at the right belongs to Pamela Anderson, but had to cut her out in the interest of the technical subject at hand ).

[Chuck S.]

Dohp!!! Everybody Got A Grin Out of That! *NM*

[Chris Patrick]

Re: Plant Photo from Noland's Vol 2

Wayne, I think the photo is pretty obvious the belt is in the back groove. I vote with you. Is this going to be another '63-'64 Judging Guide issue?

[Patrick T.]

Photo from Noland's Vol 2...

Here is a picture on page 421 in Noland's book. He mentions that '66 and '67 L-79's were the same. This one has no p/s or p/b and double pulleys. The captive belt shown is on the outside. It was a redundant feature so if your alternator belt snapped or flew off, there was the captive belt to keep the water pump running until you could get to a service station. PT