Idler Pulley Assembly

[John A.]

I have a 69 BB A/C car – which had the idler-pulley assembly removed at some point. I have been able to locate an OEM pulley assembly. But before I go through the trouble of reconfiguring the belts and installing it, are there any words of wisdom I should know before hand? Are these assemblies prone to bearing failure, belt jumping, and are they just a plain pain in the butt to keep operational?

[Craig S.]

Re: Idler Pulley Assembly

Actually, it makes the captive belt more effective by allowing correct tension. I don't know if it's still available, but there was a service bearing/shaft through GM, at least according to my parts buddy back about 10 years ago. I suspect it was a press operation to install it on the bracket as well as the idler pulley. I never had any trouble with the idler running against the backside of the belt, or any belt jumping.

[Joe C.]

Re: Idler Pulley Assembly

John:

I suppose that the cardinal rule here is : "DO NOT overtighten the belt which rides on the idler pulley". I always use the 1/2" deflection rule @ pulley-to-pulley midpoint, to arrive at a "bearing-friendly" tension setting.

Joe

[Joe L.]

Re: Idler Pulley Assembly

John------

The idler pully assemblies are not problematic. The 69-74 idler pulley assembly is available in reproduction. The bearing/shaft assembly is also available, but I doubt that you'll ever need to replace it.

[Joe L.]

Addendum

By the way, for those that are interested, the 1968 Corvette big block with A/C idler pulley assembly was different than the 69-74. The 69-74 can be used to SERVICE 1968 applications but the 2 assemblies are congigured VERY differently. Differences include the fact that the 68 assembly used a conventional pulley whereas the 69-74 used a "tensioner", non-grooved pulley. Also, the configuration of the bracket used to mount the bearing was significantly different. The 68-only idler pulley assembly, GM #3925592, was discontinued more than 25 years ago, is not reproduced, and is VERY difficult to locate. If one needs one and one locates one, one can expect to pay "big bucks" to acquire it.