Thanks...I think both the single and double grove pulleys use tensioners. I personally never had one on any of the cars I have owned over the years, yet they still did not overheat at idle. I am going to find the old stock single grove pulley used in early ac setup cars and see if I can run it without a tensioner. If not I am going to change my crank pulley and use the two grove a/c water pump pulley that is 5.5 in diameter. I know I can route the belts without the ac compressor.