Engine Coupler Questions...

[FormulaMatt]

I am getting ready to put in my stroker and figured I might as well replace the coupler while I am in there.

My question is, are the Sierra replacement couplers on par with the Mercruiser couplers? They are much easier to locate in stock. But I am worried about the price being so much lower then the merc one that the quality is inferior to the merc.

Any advice?

[MOBILEMERCMAN]

There are a number of different styles available. I think the 525 coupler is the best available.

http://www.mercruiserparts.com/Show_...ecting+Rods%29

Don't know if that is available aftermarket.. Depending on which one you presently have the flywheel housing may need to be made larger for clearance.

Sierra 18-2412 is = to merc 18311a17 They call it heavy duty. But that is not the same as the race couplers I noted above.

I would not be afraid of the sierra part.. The question for me is is the stock one enough for your application.

[FormulaMatt]

Sorry, I guess I should have given more specifics. It is a SBC Alpha Drive with presumably 450ish hp.

I am going to do a bravo swap in the fall/winter and need it to get me through the rest of this year.

How well would a stock one hold up under these conditions. This will be a pretty mild year for the boat. I have a 11 month old son I will have out quite often so obviously the boat will not be ran hard during this time. Aside from that, I will have engine break in and babying the Alpha, so again - pretty mild summer planned.

[MOBILEMERCMAN]

I show the Sierra # 18-2323 as standard SB coupler. I suggest you step up to the HD if you can since you plan to add a bravo. If not the standard would likely be fine.

The stock one for a 502 is listed above. It is also listed for use on SB. It will serve you well. Is yours now a circle plate or a triangle plate? The HD center section on the circle plate is larger and may need some clearance cut into the bellhousing.

[FormulaMatt]

I show the Sierra # 18-2323 as standard SB coupler. I suggest you step up to the HD if you can since you plan to add a bravo. If not the standard would likely be fine.

The stock one for a 502 is listed above. It is also listed for use on SB. It will serve you well. Is yours now a circle plate or a triangle plate? The HD center section on the circle plate is larger and may need some clearance cut into the bellhousing.

Thanks for all your help. Mine is presently this style. Will the one you listed be able to bolt up?

[MOBILEMERCMAN]

Not sure that style is early early. The flywheel should accept both plate types but I can't say for sure.. The flywheel cover hole will be too small as well. You would have to change the center hardware too.. It may be best to replace what you have with the same.

[FormulaMatt]

So you think I would be ok with a Sierra then?

[MOBILEMERCMAN]

I would think you will be OK.

When you make you change to a Bravo and time is on your side I would suggest looking in to the upgrade.

[FormulaMatt]

Sounds great. Thanks again for your help.

[Teague Custom Marine]

How does this coupler mount to your flywheel? Can you show a picture of your bellhousing? It almost looks like you have a transmission set up? I am looking at the application charts it appears you are using the wrong coupler?

If you havent already fixed your problem put up some pics so we can see what you are working with. I would also recommend for you to go with a HD coupler, but it depends on your current set up. -Eric

[Boat Tech]

How does this coupler mount to your flywheel? Can you show a picture of your bellhousing? It almost looks like you have a transmission set up? I am looking at the application charts it appears you are using the wrong coupler?

If you havent already fixed your problem put up some pics so we can see what you are working with. I would also recommend for you to go with a HD coupler, but it depends on your current set up. -Eric

Hey eric, I thought I would pop in just to say that you might want to keep in mind that the OP is running an old style alpha set up.

That is what the old style engine couplers looked like back in the day.

See number 23 for an example.

http://www.mercruiserparts.com/Show_...FT+AND+PISTONS

Found in here for example.
http://www.mercruiserparts.com/selec...D8+1978%2D1982

[Teague Custom Marine]

Yeah I got ya! I went back to before I was born to figure this one out.. -Eric

[Racerguymiami]

I ran that style coupler between a Merc525SC and a bravo XR run hard with no failures. It wasn't the coupler of choice but I was forced to run it but for the OMC application. I purchased a boat where the transom had been redone and was made 3/8" thicker. The added thickness of the transom pushed the motor forward 3/8" and left very little input shaft in the coupler.(1/2 of the spline) The OMC coupler is 3/4" longer so the entire splined area of the input shaft slid into the coupler.

[FormulaMatt]

Hey eric, I thought I would pop in just to say that you might want to keep in mind that the OP is running an old style alpha set up.

That is what the old style engine couplers looked like back in the day.

See number 23 for an example.

http://www.mercruiserparts.com/Show_...FT+AND+PISTONS

Found in here for example.
http://www.mercruiserparts.com/selec...D8+1978%2D1982

Yeah I got ya! I went back to before I was born to figure this one out.. -Eric

Geez guys. I get it, my set up is old!


J/K I have to keep this setup alive as long as possible until I can afford my Bravo swap. I went ahead and went with the Sierra one. I have 3-4hours on it with no problems yet. I will keep my fingers crossed.

[Pismo10]

Thanks for all your help. Mine is presently this style. Will the one you listed be able to bolt up?

I had that style on my 1979 merc 228 with R drive...Pretty old.

[MILD THUNDER]

I havent seen one of those in years!