225 Promax 2 piece adapter plate advice needed

[Wilson-Racing]

Looking for some expert advice on my 2 piece plates….I bought a good clean second hand pair as my originals are heavily corroded (like that when I bought the boat)…..The water dump hole in my original exhaust plate is around 15/32” or 1/2” and has a drill mark inside…could it of came from mercury like this? On my new plate the hole is 3/8”. Looking at pictures I have found on here all the water dump holes on these plates are 3/8”. My motor runs like a timex and I’ve never had any issues with temperature’s that I’m aware of…..so do I leave the hole at 3/8” on the new plates or open it up like the original one? What do you guys reckon?
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Cheers
Chris

[transomstand]

Interesting. Most that I've seen were 3/8" but I'm more of a 2.4 guy. The bigger hole in your old plate looks as if somebody drilled it out, not perfectly round like factory. Do you have the triangle cut out in your cowl plate or just a 3/8" hole?

[Wilson-Racing]

508536 I have a Triangle cut out in the cowl plate…..but the plot thickens…..since I’ve owned this motor it has always pissed as soon as i started it. So today I decided to pull the thermostat covers to have a look, only to find 260 1/8” hole washers in there….this thing lives in the cold North Sea and has been twisted over 6500rpm regularly in my ownership….Judging by what I’ve read on here I’m surprised this thing hasn’t cold seized on me….it goes like s**t off a shiny shovel and always starts and idles like a champ and it will troll all day if I choose to….it runs on an A23 15” ECU and has an old 20” smooth back offshore leg and sportmaster LU. Now I have the dilemma of do I just put it back together the way it was or put it back on thermostats and leave the poppet dump hole on the new exhaust plate standard at 3/8”. It also has a poppet valve fitted. I’m now wondering if I’ve just been lucky not to of killed it or if someone has spent time messing inside this thing turning it into a beast cause it certainly does shake a leg. Anyone got any thoughts?

[transomstand]

Problem is you don't know the reasoning behind the cooling system changes. Was somebody trying to reduce pressure and temp, or chasing a problem, or was it just some idiot making it a "race motor cause they don't have stats". The ProMax has a real good cooling system in it's original form, so I don't see where leaving the 3/8" hole and adding stats is going to hurt you.

[PanRonnie]

You can route the hose from the top of the block to an cowling exit tell tale (can install 2)
You now have an extra exit on the poppet cover
You can route that exit to fitting on the adapter plate (think it cools the tuner from there)
Put in the thermostats, the exits from the housing go into a single tube and route that to the tell tale
Now all is left to decide if you want to use the 225 poppet spring or the weaker 200sst spring
My alarm sometimes went off at low rpm with the 225 spring

[mragu]

The ProMax has a real good cooling system in it's original form.

Pete, truer words were never spoken;)

[Wilson-Racing]

I think my question is answered here by Wired247, post #18 & #22….it took a lot of searching to find but explains why my dump hole has been opened up…. https://www.screamandfly.com/showthread.php?299414-promax-high-water-pressure/page2&highlight=Poppet+dump+hole+size I’ll drill my new plate to replicate the old one and put it back together the way it was. S&F is awesome.

Cheers guys:)