Thread: Cog belt and pulleys, any good?

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I am shopping for a pulley set up for my BBC and have seen these cog set ups.
Are they any good? Pros? cons? I think they look pretty cool. A buddy tells me they aren't good because sometimes its better to have a belt slip a little rather than break something...

Here is an example:

I'm trying to think of a reason that v-belt slippage could save something from breaking.
Nothing obvious - other than a backfire - comes to mind and the only thing breaking there could be the belt.

If something gets into the fan, you've got problems no matter what style drive belt you're using.

The cog belt looks like an excellent way to go, especially in view of the limited amount of 'wrap' around the water pump pulley.
I run a single v-belt with about that same amount of wrap and it slips once in a while.
A newer setup with dual v-belts is expected to prevent the occasional slip bit.

A serpentine belt is something to consider as well.
There's a lot of friction with one of them and would probably be easier as well as cheaper to set up.

What you may be looking at there is a hybrid setup, the cog portion is part of a blower drive system (based on the lower pulley width), and likely a V-belt from w/p pulley to alt.

Edit; Must be poor eyesight on my part. I see a belt in the first pic I hadn't noticed before. Not a system I've seen before, interesting, but not sure what purpose (other than's Jay's comment about limited wrap) other than eye candy.

This is what I had my eye on, seems like a pretty good deal for $129...
http://cgi.ebay.com/ebaymotors/Chevy...rdZ1QQtcZphoto

If you want an opinion, these have problems. If the axis all three pulleys are not parallel, the belt will walk. The pulleys do not have guide flanges (from the picture) so the belt can walk right off the pulley. There should be a flange on one of the pulleys for the front side and one flange on the back side. The flanges dont have to be on the same pulley.

Also, the tensioning will be critical to prevent belt vibration.

Like the other guys said, a serpentine is more reliable and drives the accessories better....make sure you get the correct rotation fan and water pump.

mike in tucson

thx for the info. I am going to pass on this set up.

Certainly has a cool factor to it. True everything needs to be lined up properly to track right, but it does have the flange on the smaller pulley to keep the belt from walking. Price is right. If it's what you want, do it. Build your car for you, and have a ball. These belts run best when all the free play is eliminated, without being pulled overly tight. They just don't need it, the drive relies on the tooth and cog to drive everything and not friction, like a v belt or serpentine requires. I used the same style system to drive the prop on a homebuilt airplane, constant load at 4000 RPM at cruise speed, for hours at a time. Worked great.