I am an experienced engine builder, but I just inherited a 1978 Nordic jet boat. Very cool, but nobody on the East coast knows anything about them. The boat was set up for a big-block Chevy, and I have installed a stout small block in it's place. I bought the proper hub to connect to the Berkeley 12JG drive and installed a pressure relief valve. The thermostat housing is of course different than drag race engines. There  is a small plastic or rubber impeller with a spring. Do I need this-where can I buy one, and does the spring go on top or below the impeller? Thanks much.

If you are talking about the plunger in the thermostat housing, yes it needs to be installed, this is a check valve that keeps the stat pushed into place and allows exhaust cooling when the stat is closed.

These are a little odd to plumb, looking at it from a novice standpoint it makes no sense whatsoever.

IMHO I would take it off completely and get a simple stat housing with two 1/2" outlets...

Got any pics of your project?

More than one way to skin a cat, but why would you skin a cat? 

Your blanket statement the nobody knows about Jets on the east coast is incorrect. There are plenty of people that know about them you just have to find them. .

What type of exhaust are you running. Are you running headers. If you are then the cooling set up will be a little different. I did not run what you are describing or anything in the T-stat housing as you can see I made my own anyway.

TJ...................We're not worthy....

Obviously you don't know about jets, you had to put a blower on yours just to make it move....

GT

TJ: Your'e thermostat housing looks awesome- are the headers water cooled? Nice blower setup too!

I'm a 61 year old drag racer and have run headers (through mufflers of course) on my cars for many years. Other than noise issues, is there a good reason to water cool the headers on my Nordic? Please don't act as though I'm an idiot, I just don't know anything about jet boats. I am anxious to get it running soon and have a little fun before I tackle paint/upholstery issues. The hull looks just like TJ's except that where his is yellow-mine is black. Underneath the paint, I can see where it once said "Spinning Wheels Racing" and has a number. Ring any bells for anyone? I will post pictures soon-and any ideas are appreciated. Thanks.

I'm a 61 year old drag racer and have run headers (through mufflers of course) on my cars for many years. Other than noise issues, is there a good reason to water cool the headers on my Nordic? Please don't act as though I'm an idiot, I just don't know anything about jet boats. I am anxious to get it running soon and have a little fun before I tackle paint/upholstery issues. The hull looks just like TJ's except that where his is yellow-mine is black. Underneath the paint, I can see where it once said "Spinning Wheels Racing" and has a number. Ring any bells for anyone? I will post pictures soon-and any ideas are appreciated. Thanks.

water injection's purpose on a boat is to cool the pipes so the surrounding heat doesnt catch anything on fire or burn it.  they will *NEVER* be cool enough to touch, they'll still burn the shit out of you if you even look at them...  but at least it wont catch your upholstery and hull on fire after a long run and melt your wiring.  plus it helps keep the chrome plating on em. 

Running water through the headers helps cut down on the noise level a little (very little  )