im in toronto,ontario,canada.
found a t-stat housing flange.$47.perfect.
no-go on the t-stat.
check this-the distributor for universal in ontario (westerbeke) sells the part for $150.
they are on back order.
in fact, everyone sells them for $150 in my area,but they all order from the distributor above mentioned as does the marine store that wants to grease me for $280.
im probably going to have to eat it and pay the $280.
my freinds took time off work so i just want everything together so i dont let everyone down.
it will cost more in beer and excuses.
The thermostat is called a Holley and comes in two temp. ranges: 140 F for sea water (not applicable) and 180F for fresh water. I assume you have raw water cooling and not a separate cooling circuit.
I will tell you now that the 180F are preferable because an Atomic 4 runs cleanest and best at that temperature. 140F is a compromise due to the precipitation of salts in sea water in the ocean-going Atomic 4s. I will also tell you that a working 180F thermostat is hard to find these days and people like me hoard 'em.
Sometimes the temp is not marked on the thermostat. You get a beer making thermometer (range 100-212F) and pour hot water on the thing in a glass until you see it open. If that's circa 180F, you are good to go.
See here: Atomic 4 Updates
"Volvo #875781-7 thermostat replaces Holley thermostat on newer engines if you put it on top of a 1/8" thick spacer (in the shape of the gasket)."
You can talk to Paul at Eastern Marine on Leslie St. about this. It's a quick fix if they are in stock.
If push comes to shove, Lake Ontario is still only 12 C/53 F. You could simply put in a brass ballcock in the 1/2 inch rad hose between the side water passage plate and the thermostat housing, put it at full open, and run the engine under load for 15 minutes. If it stays at 120F, start shutting the ball valve until it gets to 170F-180F (I assume your water temp. sensor is working).
A lot of people do this, particularly where the problem isn't overheating, but "underheating".
If you are really pressed, maybe I can loan you a spare if you leave some kind of ransom
but the path of least resistance is four hose clamps and a two-barbed 1/2 inch Home Depot ball ****...and some patience.