I accidentally caught this blower belt coming loose during a burnout. Can't remember who's it was, but thought I should post it here. It was my first HAMB Drag. Had a ball! I have the full-size image if someone wants it.
I heard about him throwing the belt, but never thought I'd see a picture of it in action! great timing Now, to figure out what's causing it.....
Yep, that's me and my wayward belt. Awesome picture!!!! Thanks!! Each time as I got off of the throttle it jumped. I did a bit of playing with it when I got home and watched it move back and forth as RPM changed. I think I need some more crown on my homemade idler pulley. That and tighten it up a bit. If you look at the tank you can see Tuck's video camera. He said the video of it coming off is great. I would have rather he say the video of the pass was great but I'll take it as another tool to fix the sucker.
How much free play does the belt have when the engine is cold? I run about 3/4" deflection from straight.
I don't think my idler pulley has any crown on it. Could the idler be misaligned? how straight is the intake? It just seems strange to me that you're having trouble. I've put over 100k miles on my blower motor, never lost the belt
It doesn't appear missaligned but it's kind of hard to measure. At idle it centers, RPM accelerating it moves back and decel it moves forward. I've seen flat idlers and some that have almost .100 over the width of the 3" idler. What pitch and width of belt are you using? This is a 1/2" 2" wide.
Mine is 3" wide 1/2 pitch. The wear on my pulleys indicates it stays at the back all the time. Careful checking with a straight edge on the front faces of the pulleys should be able to tell you if it's aligned.
The idler mount could be flexing. The snout should be pretty stable, if it's built properly. The crank snout should also be plenty stable on that engine.
Belt may just be stretched on the fwd or aft side. Try installing it 180-out to see if it changes the directions that its creeping when you accelerate/decelerate...???....
I'd like to play with it tonight and figure it out but I've got some other stuff to do. Swapping it 180 is a good idea. I have a whole two passes on the new belt before it jumped. :-/
The consensus from some racing friends is that I've been adjusting it to loose. I'll check for true tonight.
Kerry, do you have a pic of your idler bracket assy?? Also, if the car never gets hot, you should maybe try 1/4 flex instead of 3/4... Try running it up to McDonalds and back then check it..... -Abone.
I was gonna suggest running it down the quarter mile and see how tight the belt gets...but that ain't gonna work is it? Try half inch, my guess is 1/4 inch is a bit tight. Something about sines and cosines
It just seems strange, I think you're in trouble. I have my blower motor more than 100 thousand kilometers, and never lost the belt..
No, I was in Missouri. This is no street engine. The speed that it gains and drops RPM with the Hilborn is nothing short of amazing. It doesn't like the deceleration. I'm convinced the biggest issue is that I have had the belt to loose. Alignment looks ok. I'm going to find a better way to measure tension, cinch it up, and do some more testing.
Kerry, I run mine ultra tight! I know that is not very technical but I use a tool intended for something else to get leverage and go for it when I tighten it. I have never had any belt drive problems or lost a belt. As you mentioned, this is not in the same department as street driven and needs to be treated as such. I have seen a lot of belts placed on race machines and never once saw them measure flex or tension.
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