Whats all this talk about pressure in the block??

[AntRant]

A simple question...In a recent forum and in past forums people talk about the water pressure in the block and how it shouldn't get to high, but what i want to know is if the water is exiting (free flowing) either out of the transom or the exhaust with how is there pressure? I understand there is going to be some but something to worry about? Also if i'm useing a ball valve comin of the jet to regulate tempature wouldn't decreasing the flow also decrease pressure? Does my setup (log/riser) make a diffrence compared to a injected exhaust system? Would the injector setup increase the block pressure? Just something that im curious about......AntRant

[flat broke]

Antrant,
I'll take a stab at this, but please don't take it as gospel. With your logs and risers, if the I.D. of the hoses and fitings that run to the logs to get rid of the water are larger than the I.D. of the inlet fittings and hoses, I would say that you are starting with a good setup. By decreasing the amount of water that comes in from the jet (also raising your temp) you further reduce the volume of water, but not the pressure. I have run 2 boats with logs and risers with this setup (no pressure relief valve) and haven't had any problems with milkshaking.
On the injected header side of the house the same basic principle applies, if your outlet area is larger than your inlet area you shouldn't be able to build pressure. However, with injected headers, you keep the water out of the headers until 1600-2000 rpm depending on your seup. You need to make sure that your bypass line that runs directly out the transom from the T valve is large enough to flow more water than your inlet side. LVJetboy came up with a great cooling diagram and writeup on how it works. You can find this on Liquidaddiction.net under pump info.
http://www.liquidaddiction.net/cooling.htm
Hope that answered some of your questions.
Chris

[Dave Wilson]

My boat was milkshaking when I got it (cheap!) and I haven't been able to fix it yet, after a couple cycles of build and tear down. I'm going to take another shot at it tomorrow. I got new head bolts and cleaned the threads in the block to make sure I torque the heads down tight. I'm going to go with a dry marine gasket this time instead of coating it with gasket sealer. I'm going to put RTV on the intake gasket around the water passages. I might even go 5 ft/lbs over what the book says for head bolt torque. But my big plan is the pressure regulator I got at Grainger. It has 1/2" input and output, and is adjustable from 3 to 50 psi. I will put it between the jet pump and the tee. I also got a 30 psi
pressure gauge to put on the intake manifold. I will be looking for 18 psi on the gauge at WOT (4500rpm), and adjusting the regulator to get that. My only concern is that the water passage in the manifold opens up, and that is where the gauge is, so I may see a lower pressure there than is present in the rest of the engine. I'll know by tomorrow afternoon if it works.

[wsuwrhr]

I am working on a bypass unit that is basically straight-through so it allows no restriction at low RPM's and it also has a dump with an adjustable regulator to control max pressure at WOT. The pressure dump is simple, consisting of a ball held closed by a spring. When the water pressure exceeds the spring pressure the excess water exits the dump.
[This message has been edited by wsuwrhr (edited December 07, 2001).]

[AntRant]

Milkshaking??

[GlastronGuy]

I had a problem with milkshakes in my 455. After a rebuild, I noticed that I had to retorque the (Al) intake 3 different times to get it to seat. I installed a pressure valve after the oil cooler and before the block. It almost fried the motor at idle, and the setting was low. I drilled and tapped two spots into the water passages of the intake, one in front, one in back. In the front fitting I installed a pressure guage, in the back I installed the relief valve and exhausted it thru transom. I headed to the lake and with my brother driving at WOT, adjusted the valve to 12psi. No more milkshakes.
I am by no means an expert and the following is just my opinion: I felt that when I closed my gate valve to regulate water flow to the engine, I was causing hot spots in the block. I like the idea of having a good steady flow to the block and having the relief valve control the pressure in the block vs before it gets to the block. Again, just my $.02

[ole war horse]

You have to have a good water flow at all times going through the engine so you don't get hot spots and try to keep the water pressure down to 15 psi cause head gaskets can't take much over that. Just my 2 cents.

[058]

Milkshake: Add water to oil, run until completly mixed and becomes the consistincy of baby shit. Not good for motor.

[Dave Wilson]

Well, the pressure regulator didn't work. I put it on the hose coming out of the pump, before it tees. Ran the boat, and the temp gauge wouldn't register. But the engine felt really hot, and the risers were real hot. The psi gauge on the regulator was reading 1 or 2, no matter how I adjusted it. So I pulled it off and replaced it with a hose. Ran the boat about 30 min, saw oil pressure dropping, checked the dipstick, milkshake city.
I used new head bolts on my Olds, cleaned the bolt hole threads, new dry marine gasket, torqued carefully, used RTV on the intake manifold gasket around the water passages. Plus this is a 1976 boat, and it looks like it's been rigged this way for a while. If there was something wrong with the flow setup, somebody would have changed it by now. I think I got me a cracked block.
Oh yeah. It's 1/2" hose throughout, except for the line from the pump to the tee. That's what size all the fittings on the logs and engine are. How could I make it bigger?

[Jungle Boy]

Rex Marine sells a pressure release valve (T) that plumbs in between your main intake hose and engine (manifold)intake. It limits block pressure to 10 psi. I have this in both of my boats and have never had a problem with either one. Too much block pressure is hard on gaskets and plumbing.

[jroos]

Dave Wilson, is the intake corroded? It may be time for a new one.
Gotta love those bench racing fags.

[Dave Wilson]

[QUOTE]Originally posted by jroos:
[B]Dave Wilson, is the intake corroded? It may be time for a new one.
What would I look for? It's an aluminum Edelbrock Torker, and I just had it beadblasted and painted. The sealing surface around a couple water passages is eaten away some, but it looks like there is enough smooth surface surrounding the corrosion for a good seal.