Thermostat Orientation in MMI Upgrade Kit

[BunnyPlanet169]

Greetings:

I purchased the thermostat kit from MMI which includes the modified housing, spacer, and 160 degree thermostat. I also go the bypass check valve and ball valve kit. I installed it this weekend, and I'm confused....

The MMI Service and Overhaul Manual (top right column, page 2-2) states: "At about 180 degrees, the thermostat will be fully open, and it's movable core will have reached the inlet port in the underside of the top of the thermostat housing..."

The thermostat in my kit measures about 5/8" high from the flange to the movable core, but the housing is only 1/2" deep. The thermostat will only install with the movable core going into the block.

So, I installed it this way, and everything works pretty well. I get to 180 degrees with the check valve, but can easily (and very quickly) reduce that with just a little bit of manual valve. That's with no load (on the hard), raw water cooled, and twice acid flushed.

My question is this: Is the overhaul manual describing an older double acting thermostat?

Thanks,

Jeff

[Dave Neptune]

Thermostat

Jeff, yes some of the A-4 thermostats did close off the bypass as they opened. This was to maintain good water flow to cool the exhaust while the beastie was warming up.

Dave Neptune