I just ordered a new set of Basset twist headers.  They are the wet style.  I know I need to set the Tee valve so the headers are almost dry at idle and then it will increase with jet PSI.  Is there a good way to go about setting this.  I would like to NOT blue my headers or flood my motor with water.

Also any input on line size would be helpful.  Right now I am thinking of -10an from pump to block openings,  then I have a thermostat cover with two 1/2" ports. One will go to the tee & the other will be -10an discharge.  Will this be to small/big?  Any input would be great.

Welcome to SCJB.
The t-valve itself doesn't have a setting. It's just the body, a spring and the ball. You just have too make sure the ball and spring are in the right order. Some guys run a control valve in between the t-stat housing and the t-valve. Restrictors are also available if you have too much water being injected.

http://www.cpperformance.com/products/Exhaust/header-accessories.htm

As far as line size, I'd have to check when I get home. But, I think it's pretty close to what you described.
Someone should chime in before then.

Thanks,  I have been a member of PB for a few years, didn't know this board was here until now.  I don't find many people in my area that run jet boats. 

I did order .100 restrictors for in the tee valve.  I just don't know what to look for as far as knowing if I have enough water or too little.  Do I leave the supply lines off the headers run it at idle and make adjustments until I have little to no water coming out? Once adjusted at idle will the spring and ball take care of the rest by itself?

Thanks for your help.
 

Thanks,  I have been a member of PB for a few years, didn't know this board was here until now.  I don't find many people in my area that run jet boats. 

I did order .100 restrictors for in the tee valve.  I just don't know what to look for as far as knowing if I have enough water or too little.  Do I leave the supply lines off the headers run it at idle and make adjustments until I have little to no water coming out? Once adjusted at idle will the spring and ball take care of the rest by itself?

Thanks for your help.

Like evilb said, at idle there should be no water. I've seen some boats have a fine mist/steam, and that should be OK. If you see water coming out at idle, that's too much and should be reduced.

The tee valve should be ready to go. The only adjustments you could make would be the restrictors or using a valve to adjust the supply.
I would install the tee and lines and go launch and idle around a bit and see how it goes. You should notice some mist coming out as you give it more gas. Also remember, there should be some weep holes on the bottom of the primary tubes of the headers that will leak water.

You asked about water line sizes. My boat has what you described in the first post. Off the t-stat housing to the t-valve, is -8 an and -8 from the valve to the injection lines.

What kind of motor do you have?

There was a guy on PB, mcderns I think, that would race his boats at Blarney Island, IL.
http://blarneyisland.com/boatraces.html

I don't know how far you are from it, but it looked like a good time with a lot of nice boats.

Thanks for info about Blarney island. It is only 2.5 hours from me... I might have to make the trip this summer...