I have Imco Shorties on a 35' fountain. After the 1st run I had 60 psi of water pressure at wot. I bought the Merc bypass valves and am now running 30psi at wot. As I come in and out of the water it spikes up to 35 psi.

I was told to run around 20 psi at wot. What are you guys running for water pressure at wot? Is 35 psi to much? I don't want to start lifting head gaskets.

Thanks in advance
T.J.

1993 35 502 carbs stock Bravo 1's...factory speed report (when new) reads 20@60mph and 22@ WOT.
Currently, mine runs upper 20's. Not looking when I'm out of the water, just trying to hang on!!

What engines are you running? 35 lbs is still too high if you are not running closed cooling. Are you running mechanical pressure gauges? Where are they plumbed off of? There is a lot of info on high water pressure in the tech section also.
Dan

i got 540s with no water surculating pum p and no thurmastat, just a restrictor plate , and my pressure at at 5500rpm is only 9lbs. a 3 mile long blast never gets over 130 on temp.

You need to get the water pressure up to 18 lbs. to properly cool the heads. Do a search in the tech section and you'll find lots of info on high and low water pressure.
Dan

hay candyman , if the blow pressure on auto is 10- to 14lbs on the radator cap. wouldent i be ok.

I'm going by what the engine experts have said in the tech section. I like your point. I never gave water pressure much of a thought until reading posts here realizing I had a problem of high pressure 35+. It explained why I went through circulating pumps so quickly.
Dan

cars can have lower pressure radiator caps cause it is closed cooling and no air is in the system[ok maby a very small amount] but on a boat that picks up sea water you get a lot more air induced into the cooling system, so you need about 20 lbs of pressure to get the air pockets out of the engines and not have hot spots

Yep, what H2X said.

Pressure is a result of restriction. You can have 100 PSI and NO FLOW!!As long as you have good flow and good temps you could be running 2 PSI and be OK. Not suggesting a goal of 2 PSI