Technical 6/71 Blower belt question

I have noticed Some guys run there blower belt tensioner on the flat side of the belt and I have also seen it ran with the ribbed section against the tensioner. Is one way better than the other? Is there a shorter life expectancy running against the ribbed section?
I am just guessing that the run it on the ribbed side for the cool whine sound.

Thanks Andy

 

To start off with when we run the racing type 8mm -14mm belts there are only a couple sizes made as far as cir***frence, so by that it is easier to run the idler on the inside of the belt for adjustment otherwise the belt would run into the fuel pump extention.
Since 1/2pitch is an industrial belt made by Gates they come in a bunch of sizes normaly every inch so you can get a belt that fits close to the upper and lower pully and then used the idler on the outside to take up the slack and with the rails on the idler keep the belt centered. On some dragsters for weight they did not run any idler and just shimmed the blower up to get tension and then put fences on the pullys to keep then put. Ribs running on the idler or backside touching makes no difference to the belt.

 

I run my idler pulley on the inside of the belt for water pump clearance. I don't think it matters. Whatever works best on a given engine/drive combination. And FYI, the belt only whines when it's too tight. All the fairground cruisers with the belt so tight it whines at idle, better be carrying a spare belt.

 

Correct me if i'm wrong, but doesn't the whine come from the air being trapped between the belt and pulley? mind is set at 7/8", and whines. does the same thing at 1"???

 

Yep !! Some drill holes in pulley to try to cut down on the whine.

 

I thought the whine was from inside the blower...

 

As our friend PBRmeASAP posted, the wine comes from the air trapped between the belt and pulley.
If you have ever been to the top end of a drag strip, and listened to a blown motor coming at you, you know how sweet the sound is.

 

Nope. Listen to a v-belt driven blower.

 

I ran my belt on the outside of the idler setup for years and had no belt wear issues.

 

A link to my car running a 1/2 pitch 671 on a 383 in a 69 camaro. The whine is from the blower and or my wife!

http://www.youtube.com/watch?v=-qg_lqO1OPI

 

Depending on the design of the belt some of the belt manufacturers will recommend that you not tension the belt from the back (smooth) side as it will dramatically shorten belt life. On most of the old school "square tooth" 1/2" pitch belts you can usually tension them from the back side. On the newer "round tooth" belts like the 8mm, and 14mm pitch belts they usually recommend tensioning them from the inside (tooth side) of the belt only.

 

Make sure you have plenty of belt slack when cold. like 1", it will be much less when the alum. gets warm. Drilling radial holes in the toothed pulleys will quiet the whine. But I love the whine.



Ago

 

Kenneth S is correct, manufacturers call it "back bending". Not many drives out there like that. They often used them to drive the water pump and the blower. I do know the back bent belts end up looking all silvery on the outside from contact with pulley. As for belt tension, about 5/8 to 3/4 of an inch is what BDS and Weiand recommend. Fwiw, I have my first gates 8 mm belt bought used in 1988, and it's still serviceable. Seen about 10,000 miles, 62 dragstrip p***es, and some land speed runs.

 

only 10k miles? I usually get 50k out of 1/2" pitch belts....

 

My first 8mm belt had about 80K miles and it was getting pretty small at the ribs. I usually got about 10K miles out of the 8mm pulleys before the ribs got really worn and sharp.

A few years ago, I changed to a Gilmer 1/2 pitch belt and pulleys. Only have 20K miles or so on it so far and the belt seems to be holding up well and the pulleys last WAY longer.

See ya, -Abone.

 

Geez, 10k miles...20k miles.....80k miles, wowsa.
I only run 'em 1/8 mile at a time but never wore one out yet.