Twisted generator belt

[Keith R.]

Any ideas on why my generator belt has twisted around so that it is just about upside down? It's a Quanta belt and I've been road testing the car in preparation for PV'ing it in Scottsdale. I'm wondering if running it up to 90% of redline had anything to do with it? I can just envision it flying apart in the middle of the road test - guess I should install a NAPA belt for the PV!

[Gary C.]

Re: Twisted generator belt

Keith,

Lots of possibilities. See if does the same thing with a good NAPA belt.

Gary
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[Keith R.]

Re: Twisted generator belt

Thanks Gary. I will do that. I am wondering if the Quanta belt is the same quality??

[Gary C.]

Re: Twisted generator belt

Keith,

1) check pulley alignment with a long 1/4" rod laid in the pulley grooves
2) make sure belt is super tight
3) Quanta belt may stretch at hi RPM
4) Check PV manual and/or team leader to see if OK to use NAPA belt or does it have to be a GM belt?

Gary
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[Keith R.]

Re: Twisted generator belt

Here's something I didn't realize in researching fan belts - there are two different part #s for 60-62 depending on whether it is a high horse power engine or not. Anyone know the difference between these belts?

[Keith R.]

Re: Twisted generator belt

Thank you Gary - all good advice.

[Keith R.]

Re: Twisted generator belt

I think that the different parts #s apply to the 61-62 models. What is confusing is that GM Wiki Parts shows P/N 3779858 for '60 to '62 with high lift cam. Corvette Central shows the same for '59 - '62 with fuel injection. Quanta shows 3759221 for all '60s. Paragon shows 3759221 for all '58 to '62 except high lift cam and 3737976 for '58 - '60 with fuel injection!

According to the JG around April '59 through 1960 all engines used the same belt part number 3759221. I'll go with that.

[Stephen C.]

Re: Twisted generator belt

Keith make sure that you have the reinforcement washer inside the water pump pulley. This washer moves the pulley slightly forward to align the fan belt. With out it the fan belt will twist or come off at high rpm's.
Not sure if FI engines had these washers.

[Keith R.]

Re: Twisted generator belt

Thanks Stephen. Yes, the reinforcement washer is in place. I think that what happened is that the belt turned on its side under high rpm loads.

[Richard G.]

Re: Twisted generator belt

I used to have the same issue on my 1957. High rpm shifts was what seemed provoke the issue. The belts with the notches, on the inside, were much worse than the ones without the notches. Confirm your pulley alignment as recommended by others. Once the belt rolls itt will continue to roll easier every time it happens. It is my theory that it's the velocity change, during the shift, is the root cause of the belt roll.

1) Confirm alignment
2) Replace the belt with a high quality US manufactured belt.
3) Slow down the shift timing.
4) Use a new reproduction belt for shows and PV testing only.

If the belt comes off you will know right away as the tachometer will quit before the motor overheats. In my case, when the belt did come completely off, it didn't cause any damage.

Rick

[Keith R.]

Re: Twisted generator belt

Thanks Rick. Much appreciated advice. It's my understanding that one can use a non-notched aftermarket belt for the PV and swap it with a reproduction belt for judging.

[Richard M.]

Re: Twisted generator belt

I have the 270 hp setup(hydr but hotter cam) in my 59 and years ago got the Quanta HP(narrower) belt for judging. It's still on there and never twisted, even at high rpm jaunts once in a while. It sits deeper in the pulleys. One thing though, my generator is actually a bit further to the rear and you can see a slight offset in the alignment. Maybe that;s why it never cane off.

Rich
ps Sorry spelling may be bad had eye surgery yesterday

[Bert L.]

Re: Twisted generator belt

ps "Sorry spelling may be bad had eye surgery yesterday"

Rich, I hope your recovery is rapid, with optimal results successfully achieved!

[Domenic T.]

Re: Twisted generator belt

Had this happen with a 59 Chevy every time I hit high RPM's. It was the generator cooling fan flexing forward because of design. It flexed and twisted the belt, also tore the belt off another time. Back then I welded a strap around the gen cooling fan blades and that solved it. Also prior to that had blades fly off the gen cooling fan and they dented the fender well and another the hood.
A bit off the belt thing but I helped a company that was testing fan blades that were attached to the water pump. A hitch hiker walk up op on a stranded driver that couldn't get his car started and offered help for a lift. When he got the engine to run he maxed it out RPM wise and 1 blade flew off the fan and killed him (the hitch hiker). The blade imbeded in his head and the company I helped was working the case.

Dom

[Perry M.]

Re: Twisted generator belt

When doing the research for my 57 FI Nomad I discovered that all three pulleys were 1/2" wide and required a 3/8' wide belt. This was supposed to keep the belt from twisting or flying off at high RPMs. The belt was also notched. As a side note, there were two crank pulleys. One was a riveted version,which was fairly rare, and then there was The "991" bolt on pulley.