I swapped out the old clutch for the fan with the new unit. i don't think anything was wrong with it but it doesn't matter. 15 minute job. I did bump the timing to about 18 degrees. (my timing tape somehow came off even though it was super glued on and clearcoated)...I need to perhaps try a little more...maybe 20 and play with the idle mixture screws a little. I got my vacuum up to 12" but I am also revving at 1100...So I need to bring that down with the next test and tune.