Im in need of the splinned upper pulley blue supercharger is older 92' sleek mercruiser small diameter 2.78 in or where to look please help asap summers comin I'm running a chiller so has to be the small one I think WOULD ALSO BE INTERESTED IN SPARE NOSE ASSEMBLY W/SAME SPLINNED SHAFT

contact the blower shop

I changed out my splined shaft to a shaft with a keyway. It was the style used on automotive blowers. You can then use off the shelf pulleys from Summit or Jegs. It worked great.

thanks for the advice should I need to go that route at least I ll know what to do

FWIW, Merc put those splined shafts on their spec 177 blowers so no one could change the pulley and grenade the engine under the 90 day warranty. When I got my new to me 525sc powered boat in 2005, I bought a 2.85 pulley with splines to replace the stock 3.25 pulley and the fit was so bad I could not run it. Then I bought another, it was the same. That's where the keyway shaft comes in. It has a much better fit and pulleys are easy to find. I ran it for 10 years and had no problems. Look at the Weiand 91180 kit.

I think I have what you need. I sent you a pm.