1966 L-79 How many belts ??

[John L.]

How many belts should there be on a 1966 L-79 with no power steering and no a/c and no K-19. The assembly manual appears to specify one belt. The judging manual appears to specify one belt. However on page 359 of Noland Adam's book it clearly shows a L-79 being lowered on to a frame and the water pump idler belt is already in place. I thought all engines other than the base engines had this extra belt in case you lost the alternator belt the water pump would still be working. Therefore I thought there shold be two belts 1) regular alternator belt 2) redundant water pump to crank pulley belt.

Help please.

john loll

[Peter J.]

Re: 1966 L-79 How many belts ??

John, This has been brought up since the last edition of the -66 JM. I haven't seen it, but if it says there is only one belt on a L-79 there has been a misunderstanding or a mistake somewhere in the latest edition. There are two belts just like in your reference in Noland Adams book. There is one belt running from the water pump pulley to the crankshaft pulley. This is a a back system to keep the water pump working in the event the other belt is thrown at high RPM.

[John L.]

Re: 1966 L-79 How many belts ??

Pete

Thank you for the response. There is a chart in the Third Edition - Mechanical Seection - Engine Balancer and Pulleys: Crank, Pump and Idler Assembly needsd to be revised.

thanks again

john lolli

[Gary B.]

1966 L-79 How many belts ? Two, I believe

John,

I believe that the chart in the 3rd edition of the 66 JG and the figure in the 66 AIM may apply to the base engine, 300HP cars and for some reason this isn't noted anywhere. I know when I bought my 66 L79 (no P/S, no A/C, no A.I.R.) that it had two belts, so I do believe that 2 belts is correct for the L79 bare bones configuration.

Gary

[John L.]

Thanks Gary *NM*

[Joe L.]

Re: 1966 L-79 How many belts ??

John-----

Two belts as you describe.

[Gary B.]

Hopefully, the '66 JG revision team will fix this

Hopefully, we can get the '66 JG manual revision team to clarify this issue in the next edition of the 1966 JG. As it now stands, I know of at least one person at Monterey who was using just one belt he says "because the JG says there is only one belt", i.e., people are altering correct cars to match the JG.

Gary

[Henry J.]

How about an L79 with P/S only?

What is considered the correct number and routing of belts for a 66 L79 with power steering, no air and no A.I.R?

[Gary B.]

L79 with P/S? '66 AIM & '66 JG (3rd ed.) differ

Henry,

This is a situation where there is a difference between the two references ('66 AIM vs. '66 JG, third edition). On page UPC 6, A4, the 66 AIM shows two belts for "327 eng with RPO N40" (P/S) and it shows that the crankshaft pulley has three grooves. In contrast to this, the 3rd edition of the '66 JG says that there are 2 grooves in the crankshaft pulley. Thus the two references disagree in regard to the number of grooves for the bottom pulley. Also, if Joe, Pete and I are correct that the L79 w/o P/S and w/o A/C had two belts, then the table in the 3rd edition of the JG may not apply to the L79 cars at all. I think I would rely on information from owners of L79 cars with P/S at this point in time, rather than relying on the JG or the AIM.

Gary

[Donald O.]

1967 L-79 How many belts ??

Same question only for a 1967, No PS, A/C, PB, or Air injection.
The water pump and the crank both have 2 groove pulleys and are believed to be original to the car.
Don

[Joe L.]

Re: 1967 L-79 How many belts ??

Donald----

Same question and same answer for your 67 application. One other thing to keep in mind: in PRODUCTION, GM rarely, if ever, installed pullies that had "unused grooves". So, if one has PRODUCTION pullies, then one should have a belt "filling" all grooves.

In rare cases, there may be an unused groove on crank pullies and, sometimes, the second groove on big block p/s pump pullies is unused.

[Henry J.]

Re: L79 with P/S? '66 AIM & '66 JG (3rd ed.) diffe

Let me describe my situation and, perhaps, someone can clarify.

I own a 26,000 mile 66 L79 w/PS only. The car is considered to be very original.

The water pump is #3859326 (no date). The water pump pulley is #3850680. This pulley has 2 shallow grooves. The pulley is fitted with the #3720616 reinforcement plate, installed in accordance with Technical Service Bulletin DR-66-40.

The crankshaft pulley is #3858533. This pulley has 2 deep grooves. The car DOES NOT have the #3751232 single groove "outer crankshaft" pulley, as specified in the AIM.

The power steering pump pulley is #3834720. This pulley is cast and has a single groove.

The car has the original alternator. The alternator pulley is #3829387-A1 (or AI). In addition, I have what I believe to be the original alternator belt #3861946 (no longer on the car).

The rear groove on the water pump pulley, the rear groove on the crankshaft pulley, and the alternator pulley appear (by eye) to line up nicely, as one would expect. This allows a single belt to route around these three pulleys.

However, it is easily discernible by eye that the front groove on the water pump pulley and the front groove on the crankshaft pulley do not line up. The mis-alignment is approximately 1/4".

Interestingly though, the front groove on the crankshaft pulley and the power steering pump pulley line up nicely and, currently, I have a belt routed around these two pulleys only.

For this reason, I do operate with two belts...but I also have an "unused" groove on the water pump pulley! This is contrary to both the TIM&JG and the AIM. Any thoughts?

[Gary B.]

Don, what does the '67 JG say?

Don,

What does the latest '67 JG says with regard to the number of belts for an L79
without P/S and without A/C? Does it say 1 or 2?

Gary

[John H.]

Re: Don, what does the '67 JG say?

Gary -

Latest '67 JG (Third Ed., Third Printing, Winter 2000) sez non-optioned or power steering-only L-79's use a 2-groove crank pulley, or a 3-groove pulley if they have power steering with either A/C or A.I.R. Also sez a 2-groove water pump pulley is used on L-79's, or 3 grooves with A/C and A.I.R., and all L-79's have the separate reinforcing plate between the back of the pulley and the water pump hub.

[Gary B.]

John; does a 2 groove pulley > 2 belts?

John,

With the L79 belt controversy, it's not the number of grooves that's at issue, it's the number of belts. You say that for 67, a 2-groove water pump pulley and a 2-groove crankshaft pulley were used with non-optioned L79's. With such 2-grooved pullies, are you also saying that two belts were used? Does this therefore
represent a difference between 66 and 67, since the 66 JG says one belt was used with non-optioned L79's? Or are you joining the side that is saying the 66 JG is oncorrect?

Gary