I have Dominators 92 jets and it's not lean. 3 x 18 should be enough cooler. Check this old thread about bypass's.http://www.offshoreonly.com/forums/s...ing+oil+bypass It's good even has pictures.

how do I determine if I have a 30 psi or a 11 psi bypass valve. How can I plug it , If thats what I decide to do .
We checked the valve today it felt like it was sticking .

My engine builder and I had this exact conversation just last week as I was curious what I had in my engine (i.e. bypass).
He told me he never uses a bypass as he likes all of the oil to go to the filter.
He also said we should be cutting the oil filters open, during oil changes, and inspecting the media for fragments.
In fact, one of our members was having oil pressure issues after a hard run. Pressure was very low at idle. He cut the filter open as recommended and discovered undesireable fragmentation. Motor came out and was disassembled to find a main bearing that was obviously the source of contamination in the oil filter. This filter inspection saved the motor components from a catostrophic failure.
Also, Oil Filter inspection is mandatory on all aircraft maintenance for this very reason.

Sorry to get off topic.

Makes no difference if it's a auto block or a marine block, they're all the same. All gen 5 and 6 have this oiling set up. Maybe all Merc engines come with the proper bypass, but if you are rebuilding, you throw the bypass away before hot tanking the block. The part number is in that other post I linked to. I agree it's better to plug it.

How do I plug it ?

My engine guy did it. I'll ask him on Monday.

I pressed a soft plug into the opening.. worked fine for several years..