Break-in 4.3 engine.. Temp?

Rustychain

Cadet
Joined
Jun 4, 2009
Messages
27
Have about 6 hours on rebuilt 4.3 L 1996 Volvo Penta engine, 4-barrel carb, in 18 ft Glastron. After having cracked block, I built it from a truck 4.3L, with help of a machine shop(bored 0.030 over & new pistons). Kept original V-P crankshaft, camshaft, etc.
Common Break in procedures say to vary speeds and run short periods of time at up to 3/4 throttle, then back off to slower RPM to let it cool down. When I run it up to 3700 RPM for a while is when it runs the coolest (approx 135 degrees) when I run a while at approx 1300-2200 rpm the temp climbs to about 155 deg. Maybe a little hotter at idle, but I've been avoiding idling.
Thermostat and water pump impellor are new.
Just wondering if it indicates anything by running colder at higher RPM's. Otherwise it runs good, just a little hard starting when warm. It starts better with throttle opened up a bit.
Used about 4 - 5 gallons of gas per hour pulling kids on a tube some of that time.
 

Rustychain

Cadet
Joined
Jun 4, 2009
Messages
27
Re: Break-in 4.3 engine.. Temp?

I think the marina said it was 150 degrees when I bought it.
I have the box the thermostat came in, the label says
BRP /OMC Evinrude/Johnson 0383307 Thermostat AY.
 

Rustychain

Cadet
Joined
Jun 4, 2009
Messages
27
Re: Break-in 4.3 engine.. Temp?

I found out the Thermostat is 160 degrees. So can anyone give me a clue what would make it run so cool? Air temp was 75 F, and water is about 75 too.
 
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