A Cure For Squeaking PulleysI have a '66 Tri-Power four-speed GTO that is restored to stock. It has power steering and I have a problem with the fan belts: they squeal all the time. I have tightened, loosened and replaced the belts. I have also tried belt dressing, but nothing works. Do you have any suggestions?Frank SheffieldTallahassee, FL
Jim Taylor responds:The V-belt drive system, as it is known, is the most practical and efficient way to turn the low drag accessories on automobile engines. The later model flat serpentine belt system has also proved to be excellent. It is by the friction of the V sides of the belt riding on the V shape of the pulley groove that causes the drive (rotation). The drive pulley on the crankshaft is how all of the accessory pulleys are driven. There is no sound more annoying or embarrassing than a shrieking belt.
Check these things out. If you have an A/C compressor going bad or a water pump or power steering unit with too much resistance, the belt will slip, causing the squeal. There are specific limits for rotation resistance of the accessories. Rotating resistance is measured in inch-lbs, requiring an inch-lb torque meter to measure it. If you don't have an inch-lb torque meter, you can simply make a judgment by hand, rotating each unit's pulley (with the belt removed). None should be hard to turn.
We see a lot of cars where pulleys have been changed and special-length belts are used. Guys are buying belts by size rather than application.
Some of the cars we see with belts that won't shut up have too narrow of a belt riding way down in the pulley groove. It is actually riding on the flat bottom of the belt, so the V walls of the belt are not fully contacting the V walls of the pulley. There is not enough friction to eliminate slip in this situation, so they squeal.
Belt dressing is for old, dry belts that should really be changed. In the old days, we held a bar of soap against a running belt. It stops all noise, but it's dangerous and there's soap flakes everywhere-don't do it.
The last suggestion is what I feel your problem probably is. Your 42-year-old pulleys have become what most people call glazed, or very smooth. The actual technical term for the polishing of brake rotors and V belt pulleys is burnishing. The V grooves in your pulleys have, over time, been so highly polished by the belts, especially slipping belts, that too little friction is generated to hold the belt against the resistance of the accessory being driven. The answer is to "scarify" (rough up) the V walls of the pulleys. Here in the shop, we remove all belts, then use an 80-grit tapered spiral roll on a die grinder to do the job. It works 100 percent of the time. If you don't have a die grinder, remove the pulleys and use 100-grit sandpaper or a rat-tail file used to sharpen chainsaw blades. We've used or advised people to use these methods and none eat belts. Instead, they provide the friction you need to stop squealing and let you run belt tension as instructed by the service manual. Thanks for the question.
Building A 400 Into A 455I love your magazine and all the great cars. My '66 LeMans currently has a mild 326. I have learned a lot and have started to put together the parts to upgrade the engine. A standard bore 400 block and a set of No. 13 heads that were done by Kauffman (240 cfm street porting) have been collected so far. I was just going to build a healthy 406, but I keep reading that a 400 stroker is about the same price. Cast cranks are available and cheap with a 4.21 stroke. Can a 400 be overbored 0.030 and be used with a standard 455 piston with stock length rods? The numbers seem to work, but I have not seen that combo in any build up. Thanks for your time.Bill MaloshSacramento, CA