Topic: Approximate retrofit date of additional A/C idler pulley?

[drummingrocks]

I've been working towards redoing the factory air setup on my '66 289 fastback.  While I don't plan on using the air that often, it would be nice for it to be functional, and I guess now's the time to fix anything while the car's still apart.  The car was built Dec. 8th, 1965, at Dearborn, and to my knowledge, never had the additional idler pulley installed to fix the belt slap on the compressor belt.  Should I consider adding this now, and if so, would it be considered concours correct if I ever wanted to show the car?  Was the belt-slap really that big of a problem?

Does anyone have a picture of the additional pulley installed, so that I'll have a reference to go by?

[CharlesTurner]

As far as I know, the additional pulley was a dealer item only.  Don't believe I have deducted for one on a car I judged.  Personally, I would leave it off, but understand that some may prefer them.

[rocket289k]

I've been working towards redoing the factory air setup on my '66 289 fastback.  While I don't plan on using the air that often, it would be nice for it to be functional, and I guess now's the time to fix anything while the car's still apart.  The car was built Dec. 8th, 1965, at Dearborn, and to my knowledge, never had the additional idler pulley installed to fix the belt slap on the compressor belt.  Should I consider adding this now, and if so, would it be considered concours correct if I ever wanted to show the car?  Was the belt-slap really that big of a problem?

Does anyone have a picture of the additional pulley installed, so that I'll have a reference to go by?

Hi there,

I've attached a picture that should provide some clarity for you of a A/C and Power Steering equipped '65 A code.  The image shows the "non-adjustable idler pulley" installed.  As you alluded to, 1965 and 1966 Mustang suffered from a condition known as "belt slap" due to the A/C compressor belt vibrating and humming due the long travel from the compressor to the crankshaft pulley (on the driver's side of the engine).  This was fixed in 1967 by a non-adjustable idler available for 1965-66 cars through local dealers.  The vibration can be felt in the steering wheel, pedals and floorboard and a low pitch rumble accompanies the vibration. This condition is usually noticeable at or just above idle.

PS - It really does eliminate the typical rumble / vibration that the 65 / 66 A/C systems suffered a lot from.

Regards,

Ron

[drummingrocks]

Ron and Charles, thanks for the replies.  It really helps to see one installed on a 289.  At this point, I'm not sure what I'll do as far as retrofitting the additional pulley.  I know I'll hardly ever drive the fastback, and I'll seldom use the A/C when I do.  I may just leave the factory setup in place for now, since I can always go back and refit the fixed idler pulley if necessary.

Thanks again for the help.