I was planning on running 160 degree thermostats in my engines. Engine builder would like to see 180 degree. He is not a boat guy so I thought I would ask here. If you've seen any of my other posts I have 500hp engines with aluminum heads. I boat in Lake Michigan. Thanks for your comments.

140 degree. shhhh….
Mercruiser OEM 140f seem to be more reliable than the aftmkts.

Quicksilver 8M0089715

Some use 120f but those are hard to find now.
We actually care about oil temps more.

your engine builder is not a boat guy ? where did he set the main and rod clearances

F2 Speedy, Honestly, at this point I'd rather not say. I have a entire $hit$how going on another post about my valve guide clearance. Maybe you could tell me safe range and I'll check my paperwork.

Around .0025-.003 on rods and .003-.0035 on mains will work fine. I have seen mains at almost .004 with no issues.

I wouldn't worry about Water Temp, get that oil up to the 220* minimum mark and you will be good to go...

Curious, what would they be on land based engine?

So.....I'm asking for a friend....what would worry you more about the clearances on the mains and rods? Too loose or too tight? Mine are really close

PAWOODCHUCK, I believe its exactly what mine are.....

to tight in a marine application with constant load on the engine they may gauld and spin a bearing, same as a tight valve guide heat expands and sticks the stem as JD showed in his post