rv

Mark,
I did the bypass hose and drilled the thermostat on ours. Configuration is #8AN bypass hose to top of thermostat housing, 140deg thermostat.

Intial setup 2 - 1/8" holes in thermostat, temp 160-170, water pressure 30psi at 3000 rpm.

2nd test was 2 - 3/16" holes, temp 140, water pressure 25 psi at 3000-3200.

3rd test was 4 - 3/16" holes, temp 100, water pressure 25 psi at 4200 rpm.

4th test remove thermostat and ran the rest of the day at 12-15psi.

I need larger bypass hose.

Has anyone tried the 4 port thermostat housing with a spring valve inside? See CP performance web site:
http://www.cpperformance.com/detail.aspx?ID=697

I would be interested to hear who has tried these.

Rick

Back4More

Thats the road I'm lookin to head down....12psi and a little water temp would be great.
I want to eventually run some 140 stats.

rv, You could still use the ports off your strainers with some KPM's and softer springs.
I'm having Dan make me some up for a test.

boatman22

Fred need info.......

MOP

From what I have read and gleaned from conversations the over pressure issue is caused more by the drive or transom pickup, not to say some after markets do not fall into the. Closed cooled rigs do not have much to worry about where as raw cooled engines can suffer from weeping head gaskets ( I know many have seen the rust on the side of the block just below the head) with closed cooling that is not an issue most of us run a 14psi cap. I had no over pressure problems with the Blackhawk drive but when I went to the dual pickup BravoX my sea strainer leaked a fair bit at speed, I crank the cover tighter for now but am working on a new idea. When you think about the pressure remember 30psi is a little over double what is run in an automotive app, the gaskets and hoses are getting better BUT!

Phil

Back4More

I'm goin with the Merc's....

US1 Fountain

Mark, I just installed a set of the Merc valves this weekend on my 100% stock 502 MPI's, other than SM exhaust. At 3500 rpm, my pressure WP gauges where pegged at 40psi. Been limiting myself to 3000 rpm this summer so far. Kinda boring, but saved some fuel.

Now with the Merc valves installed, my pressure is 30 psi at WOT. They start flowing at 25PSI. I'm going to order a batch of springs from McMaster Carr tonight and try cutting to different spring lengths to get my WOT pressure down to 15-20, saving the original springs just in case I need to put them back in.

As of a couple weeks ago when I was looking for 2, Ratman had 1 and T/Motorsports had 1 left, (I bought his other 2).

Jerry

RBeyer

I have also heard that 15 psi is more deireable. I installed one from Arizona Speed and Marine while having a head gasget problem. I run a crossover with a Pro Charged motor. At the end of the day it was a head gasket and not a water pressure problem but at 15 psi I have never dumped because of over pressure through the valve.

Rebel_Heart

I just had an e-mail from Tyler C. regarding this issue. My water pressure had been cut to 12, which he claims is way too low. He said that I should be running 20-25 so that I don't damage any head work that has been done.

How do I get my pressure back to that range?

Back4More

Yep...I also mentioned 15psi to a performance engine builder and he said 20psi would be better.

US1 Fountain

Replace your springs back to original. I placed an order last night from McMasterCarr for 6 springs that are the same as the original to experiment with. $11 .

I will say that at 25psi, my water pump hose really swells up, along with the supply hose coming from the coolers gets rock hard. I see no way it needs that kind of pressure. Maybe that is one of the reasons we hear of water pumps leaking past the weep hole?? I've done replaced 1 of my pumps with less than 150 hrs. No salt water use either. Just a thought.
I'm going for under 20psi. My previous boat had the stock t-stat housing with the brass tee for the bypass hoses and the pressure was 18psi max. Trouble free!