I'm trying to find the coupler p/n for my 1990 7.4L 330hp, can't find it, here is the link i've been searching. Am i looking in the wrong spot? Who is the cheapest place to find this part?

http://www.mercruiserparts.com/selec...asp?type_id=8I

I believe that you're looking to go here:

http://www.mercruiserparts.com/mercruiser_parts.asp

->Mercruiser Sterndrive & Inboard (Includes Diesel)
-->V-8 Sterndrive Engines
--->7.4L BRAVO GM 454 V-8 1988-1991
---->0B771113 THRU 0D603117
----->CRANKSHAFT, PISTONS AND CONNECTING RODS
and you should be looking for #13 (pn 861523A9). I believe that this is the standard one and not the HD one, but it should be fine.

what is #9 in that pic? Should i get a HD one instead?

I believe you have the triangular style coupler??

If so, it is part #18643A2 according to my trusty Mercruiser microfiche set

#9 looks like it should be for the "small bolt pattern crank"... whatever that means.

there are a few similar models:
861523A9 and
861523A11 (which I think is the one with the longer sleeve in it) search for that part number on the board, you should be able to find more info on it.

What is the engine ser # ????

Whats the part# on the high perf coupler for that application ?

I think it's more of a "heavy duty" one instead of "high performance". That would be 861523A11.


ref:drive couplers
http://www.powerboatmagazine.com/tea...2004/07_04.php

So they are saying the alum hub is better ? I seem to disagree with that.

The original coupler on your engines had an aluminum inner hub and spline. The "heavy-duty" unit that you are referring to has a steel inner hub and splines. They can be identified by the long snout extending aft out of the coupler. There is no doubt that the steel splines are stronger than aluminum. My experience indicates that the aluminum splines dissipate heat better than their steel counterparts, which contributes to increased longevity of the rubber bonding to the center hub. I have seen more instances of the steel center hubs becoming unbonded due, in part, to the transfer of heat to the bond.

I think the A11 is the one that Merc uses in the HP500s. I'd say for cloudmaster_321, the A9 would be sufficient.