Minimum compressor RPM

[Bailey28]

An update for you all:

I removed the underdrive pulley and installed the stock diameter crank pulley. The compressor now turns faster which allows for better cooling at low rpm.

HOWEVER the vibration was still there with the car in drive at a stop. Since the rear of the compressor is supported only on the bottom ears it left the body of the compressor free to vibrate.

I rigged up a 3/8" turnbuckle and attached it to the top rear mounting hole of the Sanden. I then connected the other end of the turnbuckle to a bolt hole on the cylinder head. Using proper spacers to avoid pinching the compressor ears together of course.

IT WORKED. The vibration is almost non existent at idle in gear.

I am now devising an idler pulley system to get the belt slap under control at idle.

[Tim]

Be careful with those ears. They can snap if tension is forced upon them They like a fixed brace better in my opinion. Have had many compressors over the years sent back claiming ear broke. Had one guy the other day claimed the ear fell off. Cast aluminum body/ear, fell off.

[Bailey28]

This is how I have the turnbuckle attached. I set the belt tension first. Then preloaded the turnbuckle slightly.

After purchasing the Alan Grove bracket I noticed another bracket I could have bought that has a turnbuckle included but attaches to slightly different points on the head.

I read that Sanden recommends no more than .006" ear deflection due to breakage and leaks. I set up the spacers you see on top with no slack between the ears before tightening the bolt. I had to shim the bottom mount as well with a steel shim that was about .020" to get no play as well when I first installed the compressor.

[Bailey28]

I also plan on getting a higher quality turnbuckle in the future.

The turnbuckle you see is an el cheapo from the hardware store and was for experimentation purposes.

[Tim]

Stress in that direction is much better, It's the pulling in or pushing the ear out (horizontally ) for no better term.