Well.... I was too impatient to wait for a 'real' restrictor plate, so I looked in my box of goodies and found a big SS washer. It's the washer that goes on the outside of the pivot pin. It's not a perfect fit, but it serves the purpose for now.

Hey jackhammer: Your plumbing looks allot like what I had on my jet boat. I put a thermostat housing on it that bypassed the water to the exhaust manifolds untill the thermostat opened. That allowed the engine to run between 140and 160. It was a very simple fix. Prior to that my engine ran too cool.
I think I got it from Harden Marine.

Jerry.

Like this ? I knew I might need em someday ... and Panther your absoluty right ... it was a bad move to run the bybass .. the bypass feed to the intake which would keep the thermostat cold ...and CLOSED ...I looked up what applications merc uses for those housings are plumbed and they run NO bypass ...m

Lots of good comments, and some not so good. There is no way that the original setup will work. The raw water must enter at the crossover. If you don't want to change everything, weld in a barrier in the center of the long run (between the hose sets), and plumb the bypass to go straight to the manifolds. You must drill the thermostat housing crown to bypass some water. The thermostat is automotive, which means that it is accustomed to having the same temperature on both sides of it. It can't operate properly with cold on one side and hot on the other. Good Luck.

Brownie ...lost me on the The thermostat housing has a passage from the chamber where the 1.25" and 1.75" meet to top side of the thermostat ..but it is small ... I assume it gets water flower thru the exhaust .....m

also ....sweet crossovers ....:drink:

pic in post #33. Center bypass hose connection

Yep, that's it! Get rid of the T-Stat housing you currently have and put that one on along with a 140* t-stat. Then take the bypass hose off the intake manifold and put a brass plug in. Re-route the bypass hose up to the center connection on the stainless t-stat housing and connect the hoses to your headers/manifolds to the other two. If your headers have 4 hoses going to the header you'll need to cap off the "top" bungs on your headers. With that set up you will get the benefit of having a crossover along with being able to run a t-stat.

off,
Sorry it took so long, just over run with stuff at the moment. Here are some poor pics of my setup. Looked long and hard to find these. But you can get an idea of how my is plumbed. I bought this from Stainless almost 10yrs ago. They dont carry this style anymore, at least that is what a friend told me..
The stat is a 142* and has 3 holes in the flange, either 1/8" or 3/16", I dont remember, but the holes smooth out the cycling of the temp. Without them it will get hot and then cold. I hope this helps..

D*ck

Hey Mike, it seems like you've figured out what you're gonna do to make 'em right. I've been running that housing for a little while now, but with a circ pump and the bypass. Mine seems to run alright. I'm actually running one motor with the stainless piece and one with the stock housing. They don't run exactly the same, but they never did. But so far things seem ok...consistant and predictable.
But i noticed on your little experiment with the circ pump, you didn't run the bypass hose. I wonder what would happen if I cap my bypass hoses. I was under the impression that they help relieve pressure in the block by allowing water to circulate when the tstat hasn't opened yet. I realize with the crossover it's a different animal...

The pressure was definitly higher with the circ pump ... approching 30lbs at 4000rpm ... almost nothing with the crossover .. I've had the exhaust off so we could retorque the heads and we put new rails on the valve covers ....I'm going to plumb the bybass off the crossover to the exhaust and try a thermostat ....see what happpnes ...m