[vettestr]

Hello All,
I am a Kit manufacturer and see a couple of issues that haunt cars on a regular basis. One of them is underdrive pulleys regardless of manufacturer so not picking on March, they have good quality products for sure.
I will not install underdrive pulleys in our shop because of the compounded problems they cause like overheating = low voltage that has hurt on board computers etc.... I have researched replacements and go the other direction in most cases or driving the waterpump at a higher RPM for low speed driving and heat problems. We install a simple toggle switch on the alt. to affectively turn charging off for short timed runs but then allow full charging when the stop watch is clicked off. We do install deeper grooved pulleys to keep from loosing belts at high RPM with great results. We also have our rebuilder/supplier of starters and alt. (HOT ROD) the parts to increase performance at low RPM and have solved hidden problems by doing so.
Our alternators. will have 90% output potential at 1500 rpm so no voltage sags in stop and go traffic or parades are a thing of the past. Our cooling systems or waterpump will maintain a minimum of 12PSI at 1500 RPM because this is the magic minimum pressure to ensure coolant absorbs the maximum amount of heat from engine to let the radiator do its job and run at least a 18 PSI cap always. (this was a trick Ron Davis of Davis Rad taught me) A toggle switch on the alternator plug wire allows driver to turn off charging system for timed runs but then charge at high rate when flipped back on because of other mods by our builder. Unless you have special need for the only way your car is driven stay away from underdrive pulleys. The tiny % of improvement offered for a very narrow area affects all the other parameters of your cars usage in general.