Volvo to OMC Cobra outdrive

Here goes.. Bought a 1990 Four Winns with a cracked block (cheap). Anyway, Got a sweet deal on a 2006 volvo penta 3.0L long block to replace my 1989 OMC 3.0L. Here comes the problems.

First, my OMC intake has the large ports and the new engine has small. As I want the exhaust tube to lineup with what I have, I can use the old head and resolve that problem. Another question on this later...

Second, the crank bolt pattern on the penta is smaller than on the OMC so the flywheel and coupler don't fit. Can get a flywheel for the penta, but have no idea what to do about the coupler to fit penta to cobra. Help please

Re: Volvo to OMC Cobra outdrive

I can use the old head and resolve that problem.

Click to expand...

Ayuh,... Welcome Aboard,....
That would depend on whether the old head cleans up, 'n is Serviceable...
That's Best answered by a Machine Shop...

As for the Coupler,... I don't think anybody makes that part,...
I'm not sure, I don't really do OMCs...
Seems OMC was switchin' drive systems the same time Chevy was changin' crankshafts...

Again,... Maybe the Machine Shop can adapt/ remachine your old coupler,...
If it's still serviceable...

Re: Volvo to OMC Cobra outdrive

just buy a coupler for a 1990 or newer OMC Cobra. 1990 was the year the crank went to the smaller pattern on the 3.0's by most accounts.
You can check coupler part numbers between 1989 and later years in the online parts books at
shop.evinrude.com

Re: Volvo to OMC Cobra outdrive

+1 with Howard, and I think Bond-o is thinking of a coupler to put a 1 piece seal engine to a stringer drive-that dont exist

Re: Volvo to OMC Cobra outdrive

I have reworked the old head and it is in good condition. Will check on the 1990 coupler tomorrow. I'm glad there is a coupler to fit the penta 3.0 to cobra.. Thanks guys

Re: Volvo to OMC Cobra outdrive

ok here is the update on my coupler/flywheel situation. Went to the machine shop and they are going to fix me up for a VERY reasonable fee. The guy is going to weld up both the coupler and flywheel, machine them flush, redrill and balance everything. Bond-o, thanks for the suggestion!

I still have head/manifold questions to determine which direction I want to go with that portion of the build. again, I'm working with a 2006 volvo penta 3.0L and a 1989 OMC 3.0L. coupled to a cobra outdrive. All this is in, or going in, a 1990 Four Winns.. side note: (my cobra was produced after OMC resolved the gear set eating itself and the shift linkage causing it. Mine works like a dream)

-From my hotrod days, bigger ports equaled better breathing and more power, but when you look at exhaust scavaging and various other factors, newer engines are doing a pretty good job using the smaller ports. The penta has the small ports and the OMC has large. Which head, matched to the correct intake manifold, would produce the best power? My old head has been reworked/surfaced and is in very good shape so its apples to apples on component condition.

-If I stay with the penta head, there are two ways to move with that:
First is to just buy a new manifold and match it up and call it happy, (I know it's always easier to buy than to modify, but that isn't the point in my question)
Second would be to use my existing manifold and gently port and blend the head to match the intake. Porting a head isn't a big deal, have done several back in the day, but I'm not sure if there is enough meat to open it up that far? Would I lose anything by going small to large port?

These are just a few things I'm kicking around while the weather is keeping me off the water.