wait to some of the "run it cold as possible" gang see's this thread .. Scares the hell out of me thinking of a motor running 5000 rpm @ 100* ....m

This is kind of odd seeing this topic on water temp, and the lack of it....It has been on my mind all week.
I run on Lake Mich. and as you know the water is very cold at the beginning of the season and doesn't get much past 70 Deg by August if we are lucky.
I have Blower motors with alum. heads and at the moment run with out stats.
One motor had a little more trouble keeping the oil clean of condensation than the other....so we tested the exhaust system and the intake gaskets were replaced for good measure and so on and found no leaks.
The gauge on the dash shows about 210* of oil temp and never more.
The other reads 220*.....
Is 10* that much of a difference? Don't know but this season I'm installing a Merc stat with a few 1/8th holes in it for to see what happens.

I'm building a pair of MIV 496's now ... On the test stand without T'stats I cant get operating temp .. With T'stats the temp is ok but pressure will spike over 3000 rpm ...I drilled 3/16 holes (3) and the pressure spikes came back ... So 1/8 is about right and I would start with one ? Two at the most ...m

If you're planning to install thermostats, you will need a thermo housing and crossover with the bypass hose.

I think I mistated about the holes ... If I have spikes with 3/16 holes I need to go larger ....

Oil thermostats would solve the issue with condenstation

I appreciate all the suggestions guys. I thought about running thermostats but, the other engine didm't seem to care if had them or not. My water pressure is about 20 lbs @ WOT. The engine with the problem is running a 5/8 restrictor plate. The other is not running anything. The water psi on that engine is a little less, as would be expected.

I would hate to buy a new set of crossovers with a bypass only to find out it didn't help but, I bought several different oil thermostats and that didn't make any difference so what the heck.

I guess I would of thought the stock oil coolers would be to small but, that doesn't seem to be the case either.

If gas were 1.00 / gal. I guess I wouldn't care how long or hard I had to run it to get the temps up.

Arizona Speed and Marine has a 120 deg. thermostat. Merc. has 140 and 160 degree thermostats. If you raise engine temp and restrict water through the engine with a thermostat, the oil temp will go up. Use a crossover with a bypass and use a water pressure bypass valve if nessesary to control the pressure. You're lucky you don't have the opposite problem.

I have the bypass crossovers and pressure reliefs in front of them....just no water temp at the sensors.
I have the Merc 140's to try now but thanks on the info about the 120's.