Club Cobra - Serpintine setup water pump required

Please allow me to post my solution to your problem. I had exactly the same problem and wanted to convert to a flat ribbed belt using only the crank, water pump and alternator pullies. This is a long article taken directly from my build page but I hope it provides you with some useful ideas.

"I had this urge to convert the fan belt from a V-belt arrangement to a serpentine arrangement. There were a couple of mandatory guidelines I wanted to follow. First, I wanted to try and do this on a budget rather than opt for all the high priced aftermarket BLING. Because I am running a early 351W with the original timing cover and standard rotation water pump (5 3/4" from timing cover to pulley flange) that also created a couple of fitment problems. My alternator is in the low passenger side mounting location and must remain there because to raise it up would cause interference with my FE expansion tank. Second, it cannot be adjusted forward more than 1/2" because of potential interference between the alternator fan and the right upper A-frame support on the chassis. Obviously, the alternator MUST remain in the factory stock location in order to work for me. A call to the March Pulley people drew the response that I could use their serpentine conversion kit but would have to space the crank pulley forward 1" to line it up with the water pump pulley. Then the alternator would also require spacing forward 1". The other option was to replace the timing cover and use a SHORT water pump. The March tech cautioned about swapping a short water pump onto an early timing cover, something about incompatibility of the water port holes between the cover and the newer pump resulting in a great likelihood of a leaking problem. The March Option was therefore scrapped."

"First, I removed the V-belt pulleys and took some critical measurements. My damper is 3" in depth. I measured 4 3/16" from the face of the damper to the face of the water pump flange. The V-belt crank pulley (C9OE-6312-E) has a depth of 1 1/2" from the face of the damper to the rear of the belt groove. The V-belt water pump pulley (D1AE-8509-AA) has an inside depth of 2 11/16" for a total of 4 3/16" that matches the damper/water pump distance."

"Now the search was on for the proper serpentine pulleys. I was able to find TWO different diameter stock Ford serpentine crank pulleys with a back spacing of 1 3/8", one measuring 4 3/4" in diameter and the other 6 1/8". Just out of luck I happened to spy a water pump pulley on eBay from a 1988 Thunderbird Turbo Coupe 2.4L that had an inside depth of 2 9/16" and a diameter of 5 7/8". It was ribbed and was a two belt pulley. This pulley has a part number of E7SZ-8509-A which is the double belt model for air cond. The single belt pulley is # E7SZ-8509-B. I'm not sure if they were used on other years or models but the part numbers should help there. Of course, I wanted to remove the front pulley. I found that the front pulley is merely an add-on "cap" secured by four tiny pin welds through the front of the nose. All I had to do was drill out the welds with a 3/16" drill bit and carefully pop off the front pulley. No sweat."

"When installed, the water pump pulley was still forward of the crank pulley and that would require adjustment. Using a straight edge along the front edge of the water pump pulley groove I sighted down to the crank pulley and measured that the crank pulley would need to be spaced forward 1/4" (.250) to achieve a perfect alignment. I then double checked this measurement by measuring the depth of the serpentine pulleys. The crank pulley (E4ZE-6312-A7A) measured 1 3/8" from the damper to the rear of the belt groove while the water pump pulley (E7SZ-8509-A) measured 2 9/16" internal depth for a total of 3 15/16", exactly 1/4" less than needed. Ford Motorsports offers a crank pulley spacer for the early four bolt pulleys that measures .350 thick so I purchased one of them ($28 from the local Ford Motorsports vendor) and turned it down to .250 on the lathe following the factory contour. This spacer has an indexing collar machined into the back and the front to perfectly align the pulleys with the crank damper so I made sure to accurately maintain the ridge on the front of the spacer during the machining process. The adapter is aluminum so it was a cinch to cut. Now the crank and water pump pulleys were perfectly aligned. I bolted the spacer and crank pulley onto the damper using bolts 1/4" longer than stock. The alternator was spaced forward using two 1/8" thick washers. I decided to use the 6 1/8" crank pulley (Ford part # E4ZE-6312-A7A) for a couple of reasons. First, my car is intended as a roadster, not a racer. Using the larger crank pulley will result in a slight overdrive of the water pump which is probably a good thing for the street, might help improve cooling at idle and in traffic. If I had used the smaller pulley the water pump would have been underdriven significantly and that might not have been so good. I finished off the installation with a 41" Dayco belt from my local NAPA store. OH, those guys do LOVE to see me coming. I can hear their moans and groans as they watch me pull up to the door. The entire swap looks great and accomplished all my objectives. Total cost for pulleys, crank spacer and serpentine belt, under $60.00. If I had opted for a complete March Serpentine conversion kit with timing cover and standard rotation short water pump my cost would have exceeded $600.00."