Adapting 260 cowl to 200 2 piece adapter plate questions

[Mrzip]

Buckshot Racing still has a site.

[LakeFever]

Yes buckshot Mike is a good dude I’ve purchased from him. The base plate I bought a while back from a member here. Jones marine design but his website is down now. The guy shipped lightning fast

[25two.stroke]

Jones Marine is badass. He makes all sorts of variations of the plates including ones that mercury did not ever even offer. Check out his Instagram if you can, he has most of his stuff up there and he has always responded to my PMs on there. Not sure if he has a FB but I bet he does. The factory plates had only one hole for the poppet dump so you could put them on "backwards" or "upside-down." I'm pretty sure the jones ones are symmetrical so you can't put them on wrong. I think Mike's plate is still asymmetrical. However, the 260 plate, a 225 promax plate, and a 150/200 promax plate are all different part numbers from mercury and did not supersede. They were different. The last promax I pulled apart I recall that triangle area being cut all the way out, not just a hole like are in the 260 plates. Even though in a 1 pc application the hole is useless...I think it was a holdover from the Bridgeports where they came on 1 pc and 2 pc plates. Since 2.4L 2 pc plates flow so much less water the hole was probably sufficient.

[LakeFever]

Solid info thanks. I’ll be opening that triangle up to the letter and check the poppet for stiction and ensure all passages are clear before trying again. If I find anything else strange I’ll update in case a future member runs into this issue

[LakeFever]

Took the poppet out. Looks fine to me. Removed the power head and the hole was lined up perfect. I stuffed a piece of tig wire down the adapter plate hole to make sure nothing was obstructing. All good. I removed the hose from the poppet and can blow air back through the system easy. I’d like to test the poppet with air is this something you guys ever do?

I pulled the cowl plate off and cut the triangle out completely. Waiting for gaskets to arrive and I’ll reassemble.

[LakeFever]

Still waiting on gaskets for some reason. Decided to pull the rear cover off just to be sure. I blew air through all cavities and nothing suspect anywhere. Hope the triangle opening solves this

[LakeFever]

Should be testing this again soon. I finally got the correct configuration for the bottom water feed in the adapter plate with the 260 cowl. It’s two 45 degree fittings. One is 1/8npt male/female and the other is 1/8npt male to 3/8 barb. You can use 5/16 barb too I just had already drilled the base for 3/8 so that’s what I used. The fit is perfect now.

[LakeFever]

I fired it up on the hose just now. Still getting warm but the water pressure is definitely lower. It’s showing 5psi on the hose at idle but when I rev it up a little it drops down to 3-4 or so then slowly climbs back to 5 so I’m thinking that’s pressure assist. It ran at about 150 degrees maybe 155 and pretty steady. I let it run for twenty minutes or so. Tell tale water was hot but not scalding hot just like a hot shower hot. I went to get my temp guns and out of nowhere came high wind and an absolute monsoon! Boat got soaked. I got soaked. Got it inside real quick and dried it all off. Might try the hose again tonight but planning on dropping it in the lake tomorrow.

What do you guys think of idling at 155 degrees? I’d like to see that lower but maybe ok

[Jim Speros]

I pay little attention to how hot it gets on a hose. I only run on a hose long enough to check things and assure its ready for a ramp test.
It sounds like yours is ready for ramp test.

[LakeFever]

To the lake we go! Thanks gents I’ll let y’all know how it goes

[skialot2]

Mine runs about 155-160 at idol. Around 140 at speed.

[LakeFever]

Water pressure seems normal now. The triangular hole made a big difference. I’m not leaning on it but it runs between 5-10psi up to 5000rpm it’s hard to watch the entire time but around 4psi at 1250 and up to max 10 or so at 5000. It’s definitely not getting to 15. Odd how I was super high and now almost low?

That said, it’s still getting too hot. It’s running around 180 which scares me. Fresh wisecos I’m just feeling like it’s tight and causing heat build up. Not sure how much to run it or what to do next or if this is simply normal during break in? Any thoughts?

also I think my tach is reading too high. I’m cruising at 20-30mph max and the tach is indicating 5000. Can’t be right. Barely on the throttle too

[Jim Speros]

It is in fact too low now. need 12 to 15. 12 minimum. 10 will not keep it cool. 180 is too hot. I would not run it with only 10 lbs.
I would be checking to make sure poppet is sealing properly and inspect or change impeller and confirm every little thing in pump to top of water tube is correct. Bushings at both ends of tube. Silicone strip across bridge in gearcase between exhaust and water pump. Water pump base has no sign of melting.
Sucks its still messing with you. I hope you find something simple out of place.

[rjdubiel]

I did not reed much of this thread but you are using the port side temp sensor and an Autometer gauge, below is what i see on my 280.

With an Autometer gauge my 280 HEAD TEMP runs 150-160 degrees just driving around and at WOT it climbs to 180 degrees give or take (port side merc temp sensor). I don't think the head is actually that hot.

The WATER TEMP is only around 125-130 ish max (you should see 140-145 with a poppet and 2 pc plate). The Autometer gauge hardly moves and I got a digital and confirmed 125 ish.

[OnPad]

Dang, I can see not wanting to flog on a new engine, but you might need to give it a little more speed.
From my experience running at low speeds makes the most heat. I try not to run sustained speeds between 7 and 30mph. These speeds usually read head temp of about 170° on my 2.5, and 3 litre engines. If I bump the speed up they run much cooler. I would think half to 3/4 throttle for a hour, and then only short bursts of full throttle for the next hour would be sufficient break in.

As for water pressure. My 150 supermag reads close to what your engine did before you modified the plate. A xri I have has about what your getting now. Both run plenty cool if I stay away from that 7 to 30mph range.

If your getting the tach signal from the regulator, or rectifier, a tach that is capable of reading 12 poles is required.

Are you running a stock lu? What is ptp? What prop?