I am looking for some advise, it runs great till it warms up. I have never seen the temp gauge above 130. It looks like it is starting to steam out the exhaust, then it doesn't want to idle. I changed the cooling hoses around and it ran and idled great not much steam, but when I looked at the temp gauge it was pushing 220. I wonder if I should just bite the bullet and buy the update thermostat kit, or can I make this work? How I have it plumbed now is the top 2 ports plugged, the bottom front ports going to the bottom center of the manifolds, and the bottom rear ports going to the risers.
The boat sounds great, I like the tips at water level. I don't have one of the thermostat housings off to look at, so don't take this for gospel till you look at yours, but I believe the top two ports you plugged off are the ones that give constant flow to the risers, all the time, from the little rectangle port the goes up throught the thermostat housing you have. I think the hose that goes from the bottom rear of the thermostat housing flows after the thermost opens, and the front bottom is restricted, but has flow to the log, and that may be bass ackwards, but I'm old and I can get away with things like that.
The later style thermostat housing would be safer, and look better, but there are two style of those also, like mine only has two ports on the thermostat housing to service the manifolds, and then flow from the front port on the manifold right up into the riser, I think you could do the same thing if you don't use that restricted gasket, and I have one of those thermostat housings you can have if you want to run it like that, it's constant flow. The other kind of thermostat housing, has four ports, two constant flows to the riser, and the other restricted by the thermostat.
Moral of the story ... you Must have constant flow to the risers, or it could burn up your exhaust hose's before the thermost opens. Just check it out, be sure you are not pressuring water back to the top of the thermostat, thats what the little restrictor balls do on the newer style housings, they prevent that.