Triangular coupler to round coupler, is it possible?

[Goldie627]

I have the mercruiser 140 GM 181 I/L4 1982-1986 - 6229718 THRU 0B450800.

Mercruiserparts.com shows two couplers for my motor. 76850A2 (round) and 12632A7 (triangular).

http://www.mercruiserparts.com/bam/subassembly/5643/963/300

Here's the deal, before I removed my coupler I ordered this:

http://www.ebay.com/itm/SIERRA-18-21...-/330544257513 (round)

So today I took the old coupler off and was surprised it was the triangular 3 bolt coupler. Heres were it gets tricky, according to mercruiserparts.com I can use the round or triangular style coupler. Today I noticed the vender that sold me the round coupler states that the sierra 18-2171 (76850A2) is not compatible with the three bolt coupler. This is so confusing. Will it work if i get the flywheel to engine coupling studs?

Thank you all

 

[Bondo]

Ayuh,..... Check the Flywheel Covers, there are several, some will work, others won't clear the coupler,....

 

[Goldie627]

Thanks Bondo, the coupler clears the flywheel cover.

I was also concerned because the new round coupler is about 1/2 to an 1 inch taller than the triangular coupler. So I'm thinking my drive shaft yoke is going to go a little deeper into the coupler.

Bondo, I trust you over all the venders I've spoken to but do you have any idea why the round coupler is listed as a valid option but most of the venders who sale it say that it's not compatible with the triangular coupler alpha ones?

 

[Bondo]

Ayuh,... I can't say for sure,.... I just know there's several Chevy patterned flywheel covers that aren't all the same,.....

Off-set, center-hole, 'n motor mount locations change,....
Many ya can't use the triangular coupler, if it had a crank mounted,...
Donno whether they'll interchange the other way,......

The inch ya found, may well be a Problem if the drive won't go on,....

 

[Fun Times]

I'm not to sure if this info may help you or not but just in case, here's some studying to do......(Mostly the bottom links of my past post is engine coupler info) http://forums.iboats.com/forum/engin...0#post10074510

A bit more coupler info if interested,
http://www.mercstuff.com/tricouplers.htm
http://www.amarket.com/im505.htm