69 big block water pump idler pulley belt routing question

[Stan C.]

Hi All, I am restoring my 69 big block with ac and no power steering. The car is very original with only about 25 k miles however the belts have been changed in the past with incorrect belts . I ordered the correct belts and noticed when changing them that the idler pulley with the old belts was pushing against the outside of the belt . The new belt is to long to go inside the idler pulley so i looked in my assembly manual and it shows the belt going on the outside of the idler pulley. The new belt is to short to do that so i called a corvette tech to check it out he said the belt goes on the inside of pulley. Either way my new belt is wrong but i do not know what to believe the assembly manual or the tech i spoke with . Please help . Also do you know where i can get the correct length belt. Thanks Stan

[Mark E.]

Re: 69 big block water pump idler pulley belt routing question

I'm not a '69 expert but the WP belt is pushed in by the idler pulley on every car so equipped I've seen. And it's definitely routed that way on my '70. The fit of the belt is very sensitive to its length because the belt is so short, so it's not unusual if a belt one or two lengths longer or shorter is needed.

When I restored my pulley system, I purchased the belt specified, plus two sizes longer and shorter. In my case, one size shorter fit best. Pick a length barely long enough to allow the WP pulley to fit over its mounting studs with the belt mounted on the pulley. This minimizes the amount of deflection required by the idler.

[Joe L.]

Re: 69 big block water pump idler pulley belt routing question

Hi All, I am restoring my 69 big block with ac and no power steering. The car is very original with only about 25 k miles however the belts have been changed in the past with incorrect belts . I ordered the correct belts and noticed when changing them that the idler pulley with the old belts was pushing against the outside of the belt . The new belt is to long to go inside the idler pulley so i looked in my assembly manual and it shows the belt going on the outside of the idler pulley. The new belt is to short to do that so i called a corvette tech to check it out he said the belt goes on the inside of pulley. Either way my new belt is wrong but i do not know what to believe the assembly manual or the tech i spoke with . Please help . Also do you know where i can get the correct length belt. Thanks Stan

Stan------


There is an error in the 1969 AIM regarding the idler pulley for 1969 Corvettes with C-60. The part number for the idler pulley assembly is correct but the configuration shown is incorrect. The configuration shown is a carry-over from 1968 which is different than 1969-74.

The 1968 configuration used a pulley with a groove. In this configuration the belt was installed around the pulley and in the pulley groove. Thus, the inside of the belt (i.e. the narrower part) installed into the groove.

The 1969-74 configuration used a pulley with no groove. In this configuration, the outer diameter of the pulley bore against the outside of the belt (i.e the wider part of the belt), pressing it slightly inward.

[Stan C.]

Re: 69 big block water pump idler pulley belt routing question

Thank you so much. What i relief to know for sure. We should see about changing the assembly manual or at least add a foot note to eliminate the confusion.

[Tom L.]

Re: 69 big block water pump idler pulley belt routing question

Did you order Quanta reproduction belts? Several years ago when I got all of the belt routing corrected on my car I found that a quanta belt was the only one that would fit correctly for the idler pulley belt. Belts from my FLAPS were either too tight or too loose. Good luck!

[Tom L.]

Re: 69 big block water pump idler pulley belt routing question

Did you order Quanta reproduction belts? Several years ago when I got all of the belt routing corrected on my car I found that a quanta belt was the only one that would fit correctly for the idler pulley belt. Belts from my FLAPS were either too tight or too loose. Good luck!