225 promax with one piece adapter plate

[transomstand]

The thread has lost focus Tony. Your method is perfectly fine and proven. I was hoping to create the "next generation" mod here that would most closely resemble a 2 pc installation using stats and poppet and require no further tweaking or adjusting after completion.

I've learned enough through this discussion that I would now consider a 1 pc installation on my own setup and would no longer have to listen to Ronnie howling about my 2 pc plate on his 15" mid

[transomstand]

You are right. I got the adapter plugged at the rear. Just ran it like that. Later I installed fitting and plumbed like factory. No noticable difference. I preferred the plug. No hassle with plumbing for cowl and skirt. Also 1 hose for each stat. Easier to spot problem with a stat.

You DO realize that you proved the "dry mid" concept by this mod? Fed by nothing but poppet water?

By plugging the feed water to the 2 pc plate no water was entering the mid until the poppet opened.

[bigboy]

You DO realize that you proved the "dry mid" concept by this mod? Fed by nothing but poppet water?

By plugging the feed water to the 2 pc plate no water was entering the mid until the poppet opened.

Stay focussed bunnymeister. Dont forget the hose from the top of the block that is connected with the poppet cover. The poppet cavity gets feeded at all RPMS. Also at lower speed when the poppet is closed. Even the the tuner gets cooled. Thats why I think mother merc goes from the full footprint poppet size to a smaller hole. It works restrictive and pushes water in the channel to cool the tuner.

With my 2 piece plate I disconnected the fitting at the rear of the adapter with a running engine. Actualy water was comming through the fitting. So in other terms with the fitting it might spill more water than pushing through the tiny holes to cool the tuner.

[transomstand]

I can't see how a 1/8 hose fed to a 3/8 drain is going to develop enough pressure to feed the exhaust plate any significant water.

I have to move on to Sportmaster hydrodynamics this afternoon anyway, got some things bugging me about the way the Ventura handled at the Romp.

[bigboy]

I can't see how a 1/8 hose fed to a 3/8 drain is going to develop enough pressure to feed the exhaust plate any significant water.

I have to move on to Sportmaster hydrodynamics this afternoon anyway, got some things bugging me about the way the Ventura handled at the Romp.

I do agree in theory but if memory serves me right water was spraying out when running engine at the hose from the adapter plate when I disconnected that hose. Maybe the popet valve also lets a small amount of water through at idle. In fact you should take notice from those experiments. Anyway you dont need the spent cooling water of the stats dumped in the adapter. I ran my engine with two hoses dumped outside and 2 pc plate. Also idled for maybe 15 minutes without any problem.

The only thing I am wondering is if spraying water on the tuner would prevent the water mist comming through the exhaust relieves. This was not a problem with the 2 piece plate. So is it because of the tuner coolant or just the exhaust travelling through the adapter plate? I have no clue. On the 1 piece plate the exhaust leaves the mid a lot directer.

Have fun with setting up the sporty for your boat.

[bigboy]

Someone know the cooling scheme off the 225 promax on a 1 piece? From what I read it has t-stats and a poppet. How much and size holes in the adapter? Any mods to the cowl baseplate? How are the hoses routed?

[Greg G]

In 20" Promax motors the only one with a 1 piece was the Offshore model.

[bigboy]

I dont give up...

I think this method will be a lot better. Lets hope...

[Steve Pope]

See post #54 Popey

[Go Time]

Yeah Popey, but it appears he blocked the poppet discharge cavity too.

[bigboy]

Did not block the poppet discharge cavity in the plate.

I now drilled a very small drain hole in the base plate.

I stil have the popet cavity in the adapter. I reduced the dump hole here and drilled so its exactly aimed at the waterpump.

I drilled a hole in the side of the poppet caviy in the adapter.

So closed popet water flows in this cavity from the top block fitting. This water will spray right on the water pump. With openee popet the water will leave the popet cavity and leave the adapter via 4 holes which were originaly in the adapter.

[Steve Pope]

I found out how the popet valve on a promax with a one piece exhaust plate works. The lower pan plate does not have the holes in it as in pic on post #233. It still has the popet dump hole. The only exit path for powerhead water is through the popet valve and thermostats. I have a factory original 15 inch promax 225x in the shop with the power head off. I checked where used part number and the lower pan plate is unique to a 15 inch promax.

[Greg G]

I found out how the popet valve on a promax with a one piece exhaust plate works. The lower pan plate does not have the holes in it as in pic on post #233. It still has the popet dump hole. The only exit path for powerhead water is through the popet valve and thermostats. I have a factory original 15 inch promax 225x in the shop with the power head off. I checked where used part number and the lower pan plate is unique to a 15 inch promax.

Any chance for close up photos. I believe that a factory 15" "X" is unique and possibly different than the older Promax.

[Steve Pope]

Hi all. The 15 inch 225x was the only factory promax with a 1 piece exhaust plate and has a unique bottom cowl plate to control water through the popet valve. It also had water diverters in the block. Just copy the plate as per post 233 or cut a new plate without the 4 holes, that is all the factory plate looks like. I have plugged the holes as per post 233 on early pro max when changing to a 1 piece exhaust and it worked great.

[Go Time]

Popey, thanks for clearing up the 225/1 piece cooling mystery. I worked on a 225 Promax (not an X)15 inch with a one piece that appeared to be a factory motor. I did not remove the powerhead so I can’t speak to the configuration of the cowling base plate, but I believe 225 Promaxes also came with 15” mids and one piece adapters.
I have a one piece that we built the poppet discharge chamber in and blocked the 2 drain holes (except for a small drain hole) so it works like a 2 piece. I finally ran it and it worked great.