mightyraydawg

ME:
I've been a gearhead since 1964, but I'm relatively new to boats. My brother has owned several drag boats over the years, but this is the first offshore boat.

THE BOAT:
My brother just got this boat wth a big, fast low-hour 588 Merlin-block motor in an OffShore rig, but sees very little use above 3-grand. Only rarely full-throttle, and then only for 10-15 seconds at a time. I realize we're, essentially, driving a Ferarri in a Christmas parade, but the boat should work a little better than it's currently doing.

THE ISSUES:
Low oil temp, low coolant temp, carburetion is rich, plugs black, oil gets black, etc.. I know what to do for each of these, as well as how to do it. But this is a boat, not a car, and there are caveats and dangers... hence, my joining and posting to this forum. I need some expertise so I don't poop in my brother's very expensive nest.

BY-THE-GAUGES:
Built to survive tortuous, full-throttle marathons, this monster runs TOO COOL in (our) normal use. Coolant temp runs around 100-degrees on lake water (South Carolina), and the external cog-belt driven H2O pump drives coolant pressure to around 6 PSI in normal use. Oil temp is LOW, much lower than I'd like to see it, and the oil gets dark quicker than I'd like. I think we'd be way ahead of the game if we could wrestle a THERMOSTAT into the 588 Merlin and stabilize the coolant temp. Maintaining a reasonable coolant temp would also allow carb jetting (giant Dominator) to be made crisper as well, likely fixing the dirty oil issue while lowering fuel consumption to boot. It'd be win-win all around, but for the bugaboo..

THE PROBLEM:
A standard GM thermostat would fit right in the coolant neck on the top/front of the engine, but it appears to me that all water to the header boxes comes through this two-pronged neck, and is Y-ed off with one line to each bank's header box. And while the thermostat would GREATLY restrict the flow of lake water to the engine (good) it would also restrict water to the header boxes; very bad. The thermostat would also VERY likely drive coolant pressure WAY up the scale. Why can't life just be easy?

WHEN I WISH UPON A STAR:
I welcome any recommendations as to getting a coolant thermostat in the block while maintaining flow to the header boxes. In my dreams, someone would make a version of the big, chromed coolant crossover tube (on the front of the block) with a built-in adjustable pressure regulator plumbed with a "pop-off" bypass line, which could be T-ed back into the header's coolant tubes. And perhaps there is such a thing; I'm just too new to know.

***
I can tune the Dominator and address and/or fix most of the above maladies, but I still think that, considering the Merlin II's current useage, a stable block temp would go a long way toward making it a more civil water toy.

Thanks for any assistance and/or ideas on the matter, and I very much look forward to using this forum regularly to complain about something; even if I have to make it up as I go. (chuckle)

jrc in SC

Brad Zastrow

Performance engines do not run tstats. An open cooling system can not heat the blocks like a closed system. You could run oil thermostats to get your engine oil temp up. I may have some Keith Eckerts Oil stats I might sell from a rerig on my boat. They restrict the oil flow to the coolers when cold. Water temp will stay cool most of the time. My engines never really warm up like you are accustomed to with a car.