BadDog

If you are going to run a T-stat you need to have a means to control water pressure and a bypass strategy. Do some searching and you will find the info.

I have a sort of homemade rig with less than 30 bucks into it. I can run in ice cold water or summer heat. Water temp is stable at 120 within 5 minutes, water pressure at 2 to 5 idle, about 15 at cruise and close to 20 at WOT. Oil temps steady at 170 and 210 WOT. 502 with blower. Not hard to do just pick what works. Not likly one off the shelf setup will do it.

pullmytrigger

please explain.....

Chris Sunkin

Run your pump output to your exhaust manifolds, then into your engines. That will throw some heat into the water without alot of fooling around. You have to be careful though- if you have alot of skirt clearance and the blocks stay cold, you'll crack skirts.

BY U BOY

Here is what you need.You will also need the hose and a 140* tstat
http://www.cpperformance.com/detail.aspx?ID=641

BadDog

My setup is a little different but it would work the same as the one in post 14. Water pressure will become an issue without some sort of dump valve arrangement. You can purchase the mercury one but no guarantee it will flow enough or dump off at a low enough pressure. It seems it has a lot to do with hull setup and speeds etc.

Setup a pressure gauge by removing one of the block plugs and screwing an adapter for your pressure gauge. Merc makes one that is used for ob apps or just use a temporary gauge while setting this all up. Your target is low pressure at idle and no more than 20 at wot. The bypass portion of the housing is what will cool your exhaust while t-stat is closed. You will need some small holes in the t-stat. While thinking of t-stat Arizona Speed and Marine has high flow 120 t-stats. You will need a hole or two of small size in the t-stat. This allows it to pass some water so that it will not cycle from open to close. This is a trial and error thing so start with a 3/16 hole. Without the hole the t-stat will be slow to come up to temp then when it opens it will close again as it gets a slug of cold water. The hole allows it to come up to temp slowly and then stay open. Not sure where I ended up on the holes but I believe two at 3/16. The hole will also increase the amount of water to the headers while stat is closed.

On to the dump valve setup. Many have used the Merc dump valve with success, others found it did not pass enough water or still caused high pressure. They are expensive. The dump valve needs to go after your oil cooler and before your block. This causes more water to flow through your cooler when the dump valve is in operation thus dropping oil temps. I setup up a section of hard pipe after the oil cooler and before the block. In this pipe I mounted two dump valves with their output connected via a Y to dump overboard directed to flow straight on to the top cap of the Bravo. I am also using the Simreck Drive Shower. The dump valve output sprays a steady stream of water on the top cap when on plane. One of these dump valves is set to open at a low pressure and the other at a higher pressure. It was sort of a balancing act but not difficult.

I think once I had it all balanced out the first dump valve was more of an open valve and the other popped off at higher RPM. I may have been able to accomplish the same thing with a restrictor and dump valve.
See http://www.mcmaster.com/ and search pressure valve. I am using two 9763K11 with 0-50 Y’d to a ¾ inch line. I should have used a 1 inch line after the Y.

This setup was fairly simple to rig and works well. At idle one of the valves is passing a fair amount of water and as RPM increases the other one starts to open while the first is fully open. What I have ended up with is about 2 to 3 psi at idle when hot and 5 to 10 when cold. As rpm build pressure gauge shows steady climb to a max of 20.

Works for me but others may have a simpler method.