Fanbelt Fun - Corvair Fanbelt Craziness

Subtitle: What happens when you run a Corvair belt too loose
I had some issue with belts jumping and throwing after loosening guides (to try and eliminate a burning belt smell from them rubbing) because of my need (!) to do a lot of heal-toe downshifting. Lots of belt death resulted. I decided to put some cameras on the situation to see what was really going on in there!
I might need to devise a new guides. I have a block of teflon to create some non-stinky guide "skids".
An update after some further experimenting (another video to come): I looked at and setup the belt to factory manual specs and boy is that spec tight!! One important aspect of it though is VERY tight guide clearance (as in 1/8 inch). Setting the belt to near stock, but not as tight, makes for much less belt craziness. Currently I would suggest tight guides, and a bit tighter than the "move the alternator with one finger" method for the belt. (only really needed for spirited driving of course)
Engine is not stock. 9.5:1 compression, ported heads, headers, 2.9L, cam....

[@TonyK3130]

Spring loaded idler ala Yenko, Aikins, and Thompson is a hardware store fix that is a lot cheaper than blown belts

[@63turbo]

On my 140, I set both guides as close as I could without having them touch... 1/16" or less and had ZERO issues with belt life or anything, although I did set the belt a little more snug than light alternator dragging when cold.

[@timcarlos]

GM should've added belt tensioner(s) or similar.

[@larrysorenson4789]

I ultimately got to the point where I could replace the belt in the dark. My secret was to remove the distributor, carefully, and replace it after the belt change.

[@larrysorenson4789]

So is the answer a big spring tensioner on the return side?

[@jakespeed63]

Good science experiment and video. Crazy thing....30? years ago, my sister's 110 4speed, had a Clark's spring-loaded tensioner, that my brother-in-law had installed. Borrowed that car one summer and drove the snot out of it and never ever blew a belt. NOW I take care of 3 Corvairs for a friend. HIS 140 4 speed convertible, does not have a spring loaded tensioner (nor do the van or wagon) and never has a problem, but he drives it like the old man that he is. As a veteran mechanic, the whole spring loaded belt pulley seems like something, GM should have done from day one. So, are you installing one??? JT: Orlando, FLA

[@kirstenspencer3630]

I had a early spring loaded belt tensioner ( IECO brand if I remember correctly ) never lost a belt after installation. As the spring was fixed to the rear sheet metal it did make a drumming noise amplified by the tin. Carefully installed with the metal belt guides the belt gives little trouble. To remove and tension the belt I use a long 3/8 drive with a universal to EASILY get around the distributor.

[@old-corvair-guy]

U will learn to drive the corvair with out fan belt for miles and no engine damage. Forgotten to restock gates 8208 belt. Don't ask ,it was fun that day.

[@larrybruce4856]

An idler wheel tensioner would be the best solution as in tightening the fan belt too tight will cause the fan bearing to burn up and that gets expensive as the fan bearing is a "pressed" bearing, difficult and costly to replace.

[@johnabriggs6044]

As I once own a Corvair I found that Gate Green leaf belt with a steel core worked best. once stretched the first few hours of running Never had any issues driving mine hard with the Four-speed manual shifter. Would say find whatever new fan belt company has a steel core and use it.

[@kirstenspencer3630]

Gates products are Quality..

[@MrNapaCorvair]

Soooo what have we learned from the two different belts?

[@fanbeltconspiracy]

The belts were really just sacrificial belts because I was expecting something bad and did not want to trash a nice belt. The first belt had been thrown and was in rough shape, the second one was nicer but had done some over the guide rubbing previously. I guess the lesson learned would be that thrown belts (first one) will do weird things (that weird flapping on the tension side) if you run them again. I am planning on doing some more trials with good belts. Maybe test the difference between different belt tightness. I also have a spring loaded idler that I would love to see what it does under more extreme conditions. Could get interesting. This video was really more a general curiosity as to what belts actually do when driving. Probably not representative of "normal" driving, or good belts in all cases. I also did just figure out why the second belt had the fraying on the outer edge. It was hitting the distributor hold down tab. So, clearly not tight enough (or there needs to be a guide there).

[@fanbeltconspiracy]

One more note: After replacing the last belt with a new belt and driving a bit (not terribly aggressively), I noticed some wear on the edge rather quickly. I discovered that wear appears to be coming form the distributor mount, so the belt was loose enough to hit that. So, setting the belt tension to "so you can just turn the alternator with one finger" is not tight enough for spirited downshifting. Should be fine for less aggressive driving though.

[@v.e.7236]

@@fanbeltconspiracy Never did agree w/ that "one finger tension" adjustment and have found that if you snug it up so you can just turn it w/ your hand (not just a finger) you're golden. Those spring tensioners work well also, as I run one from Corvair Underground on my '65 and never experience belt tossing or flipping. Not sure why it took so long for Chevy to figure out the belt guides next to the fan pulley, but those were/are great additions to any/all Corvairs. Stay safe.

[@63turbo]

@@fanbeltconspiracy yes- I find that its best to set the final tension with the engine warm and go for a tension that will allow the alternator pulley to still slip a little with some effort. This is with a steel pulley that has all its paint removed and shiny (makes a huge difference-the paint is more sticky than aluminum is!), although with an aluminum alternator pulley like you have, that same dragging sensation may end up resulting in a tension thats too loose. I know that Mr Sedman did a small run of steel alternator pulleys to work with your existing alternator fan and nose cover, and it might be worth checking with him if he has anymore.

[@wardmontgomery9259]

I’ve seen Corvairs with an electric fan mounted on the bottom of the hood - cheap insurance