L79 belt question

**Duke W.** · December 17, 2003, 09:34 PM

Re: L79 belt question

Early L79s had two belts, but later models had one. The best source for technical specifications including belt length is the "restoration package" available at no charge from GM customer service.

Mechanical lifter 327s had the dual belt setup along with the large baffled pan with windage tray. The dual belts with deep groove pulleys contained the belts better at high revs. These engines were used in SCCA racing and back then the production classes were near showroom stock with very few allowable modifictations.

The L-79 was initially considered to be in this category, but was later "detuned" to use the word loosly by substituting a single belt drive and the smaller pan to allow a power steering option.

The L-79 was never intended for serious racing, but was intended to include the best features of SHP/FI engines in terms or high output with a more "streetable" orientation.

Duke

**Marzio Cano** · December 17, 2003, 10:00 PM

Re: L79 belt question

Thanks Duke,

Never knew that about the L79.

Now how do I know when the L79 was switched over to a single belt set up? I believe that I already have the GM technical manual that you mentioned. It was sent to me free of charge after making a phone call. That is where I noticed that the L79 seemed to have TWO belts listed. Either way the "Generator or Alternator" belt is listed at 54" while the 327/300hp motor is 53.25", which is the length of my old belt that is a GATES brand. Incidently, the GATES website lists my old belt application to fit both the 300hp and 350hp motor. ??

MC

**Rich G.** · December 17, 2003, 10:59 PM

Re: L79 belt question

My 66 L79 built early Feb of 66 has the 2 belt set up, although I don't have the second "captive" belt installed. I'm pretty sure this car has the original L79 in it. I have not had to change the belt, so can't say what size it is.

Rich Giannotti

**Duke W.** · December 17, 2003, 11:56 PM

I think I goofed!!!

Another member questioned me on this in a private e-mail. My prior post is probably in error. I was reminded that later L-79s had a second "captured belt" around only the crankshaft pulley and water pump without the idler/tensioner that my '63 L-76 has.

A further check of pulley's in my parts catalog indicates the 3770245 coolant pump/fan pulley is called out for all late '62 to '68 w/ SHP/FI w/o A/C; double grooves 7 1/8" OD. This would include all 327s from 340 to 375 HP. (Another wapullye is called out for SHP with A/C.)

The 3829921 idler pulley was used on '63 to '65 SHP/FI exc. A/C or P/S, and was not used in subsequent years.

The only SHP 327 after '65 was L-79, so all indications are that without A/C or P/S it used dual belts with one "captured" on the coolant pump and crank pulleys without the idler tensioner and the other tensioned by the alternator.

Sorry for the prior misinformation.

Duke

**Gary B.** · December 18, 2003, 11:42 AM

1966 L79: one belt or two? Definitely two.

Marzio,

My July build date L79 has the two belts and no A/C, no AIR, no power steering. I believe all 66 L79s so configured should have two belts. Unfortunately, there is some confusion that has crept into the 3rd edition of the TIM&JG that implies there should be one belt. Based on my survey of about half a dozen 66 L79 cars, the TIM&JG is incorrect and two belts (one redundent, captured; one for the alternator) is correct. Unfortunately, now that the JG has it wrong, I've seen cars being judged with just the one belt since the owners don't want to get a points deduct even if they know or believe the JG is incorrect. Hopefully, the editors of the 66 JG will nip this in the bud before a new generation of owners think that 1 belt is correct and the future 4th edition of the JG will get it right. Keep your fingers crossed.

Gary Beaupre

**Gary B.** · December 18, 2003, 11:46 AM

Minor correction

Marzio,

I think I mis-spoke and it's the latest 67 TIM&JG that has the incorrect number of belts for the no-option L79 equipped cars. I don't have the 66 and 67 JGs at hand, but I think I'm now remembering things correctly. In any case, the 66 L79 no-option cars should have the two belts.

Gary

**Patrick T.** · December 18, 2003, 04:09 PM

Re: L79 belt question

I have two belts on my '67 L-79, one around the crank/waterpump and one for the alternator. The purpose of the short one is if your alternator belt breaks while you're driving, the water pump will still work so the engine won't overheat and you can probably make it somewhere to get another belt.

Those short belts are PIA to install though. The L-79 alternator belts listed with the vendors are too long. I got the 327/300 belt and it fit perfectly.

**Tom Merkel** · December 18, 2003, 05:53 PM

Re: L79 belt question

Same for me - 2 belts on my '67 L-79 with NO ps, pb, a/c, smog.

Tom

**Gary B.** · December 18, 2003, 06:45 PM

L79 belt question for Tom & Patrick

Tom, Patrick,

Doesn't the latest 67 JG have a table that incorrectly indicates one belt for L79 with no PS, PB, A/C, or A.I.R.? Somewhere I've seen such a table. It's in the latest edition of either the 65, 66 or 67 JG. Hopefully, the table won't propagate to the JGs for the other years before the mistake is corrected.

Gary

**Marzio Cano** · December 18, 2003, 10:51 PM

Re: L79 belt question for Tom & Patrick

Thank you for all the responses.

One question which is still unaswered for me. Can a L79 be set up with a single belt set up like mine? Logically I would think so, but any opinions? I ask because I'm already doubting the originality of this motor.

And lastly, how extensive would it be to switch over to a double belt? Is there more to it than just switching pulleys and belts?

Thanks, MC

**Tom Merkel** · December 19, 2003, 07:28 AM

Re: L79 belt question for Tom & Patrick

Gary - Yes, the subject of L-79 "number of belts" was previously discussed in depth on this board I'd say within the last year, and I contributed to that discussion as well.

Being original owner '67 L-79 (no p/b, p/s, a/c, smog), there were 2 belts installed, not one.

I also remember there being quite a discussion about the accuracy of the published information in NCRS judging guide (?), tech manual (?), etc. to accurately reflect this fact.

Anyhow, my recollection is that someone along this board with specific interest in resolving this debate was going to speak to a judging chairman (?) who has the ability to update those pubs that innaccurately documented the L-79 "# of belts".

Lastly, I don't have the pub(s) in question, so I'm unable to be more specific or cite page and verse.

Tom

**Gary B.** · December 19, 2003, 10:52 AM

L79 belt question

Marzio,

Sure you can set up any such engine to work with one belt and a single groove pulleys. You can also set up any such engine to work with one belt, just by removing the second captured belt, but keeping the two-groove pulleys on the water pump and crank. This is what I've seen a couple of people do for judging, who mistakeningly removed the 2nd belt thinking it was incorrect.

But two belts are correct. No doubt about it. Sooner or later the 65-67 TIM&JG editors will all agree and get it right.

Gary

**Ken K.** · December 23, 2003, 07:20 PM

L79 belt question "two" belts.

O.K. Here is a question. Does anyone know the size of the small belt? And if there is a easy way to install that belt onto the just the two pulleys? Is this "two" belt thing correct for a 1967 L79 built in February? Are both the pulleys black in color or chrome? Thanks Ken

**Joe L.** · December 24, 2003, 01:01 PM

Re: L79 belt question "two" belts.

Ken----

The belt between the waterpump pulley and the balancer pulley is 3/8" X 34-3/8". It's a special lengrth belt that you won't find in any auto parts store and it's GM discontinued. A currently available GM belt of GM #9433722 which is 7/16" X 34-1/2" may fit correctly. Otherwise, obtain a reproduction belt from Quanta.

Your car used pullies with 2 grooves and 2 belts. In addition, I am aware of NO Corvette application for which, originally, there were "unused" pulley grooves.

Installation of the "captive" belts was extensively discussed recently. It may still be in the active thread list or in the most recent archives.

Your pullies were either semi-gloss black painted or finished in black phosphate. Many of the original waterpump pullies for your application were black phosphate finished. NO Corvette pullies were EVER originally chrome--- from 1953 right through 2004. ANY chrome pullies or machined aluminum pullies are aftermarket. Absolutely. Positively. Period.

L79 belt question

L79 belt question

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