I installed emi thunder manifoldes with the stainless riseres . My question is what t-stat housing do I need to plum the manifolds? I have this set up installed http://www.go2marine.com/product/776...-87290a23.html

That should do fine. Just plumb those upper two outlets on the t-piece to the inlets on the lower sides of the EMIs. I'd also suggest a 1/8" hole drilled in the t-stat to ensure flow to the manifolds while the engine warms up.

You will need to install a couple of Y fittings since you have 4 outlets from the thermostat housing and only 2 inlets on the exhaust. The Y fitting will join the 2 outlet hoses from the thermo housing into 1 that will go into the exhaust.
Eddie

You would be better off with a two outlet housing, those pressure ball housings are for heated manifold. The spring loaded balls are there to insure water to the risers before the Tsat opens. Also a two port housing will cost about $100! Check the two offered by San Juan in this link http://www.partman.com/cooling.html?cat=5559&p=4 you will need to drill a 1/4" hole in the Tsat.

Will this flow enough to get the water out and keep.engine temp s normal?

http://www.partman.com/thermostat-ho...-design-3.html
this what I am thinking of using. What temp t stat to use?

I just went though this whole ordeal - order the Stainless housing and be done with it. I got mine for $168.00 P/N 18-1989 Here's the link and it was free shipping!

http://www.marinepartssource.com/new...&mfgno=18-1989

Check out my old thread.

http://www.offshoreonly.com/forums/g...i-exhaust.html

Hope this is helpful, by the way the thermostat housing DOES have an internal bypass built inside it, its not a spring loaded deal but its a small little passage way.

Thanks for the link. I orderd it. Next question is what thermostat to use with that housing?

You will need 2 Y pipes per engine and plumb it this way see pic