Why does this work? Steel sleeve european XR2 on one piece adapter

**RoyE** · 06-04-2020, 03:45 AM

I have a first gen mercury racing european XR2, it is a non-fat block 2 liter. It sits on a one piece exhaust adapter. It has no poppet valve with the poppet cover with a dump and 7/16" washers instead of thermostats. I want to use the single ram trim and one piece exhaust adapter for multiple powerheads so I can swap, for now only 2 liters, both fat block and non-fat block.

If I take my fishing 2 liter fat block, and use the washers instead of thermostats and remove the poppet and put the poppet cover with dump on, will this work with cooling?

What is different in my one piece adapter plate compared to let's say a 260 one? I read in other topics about steel sleeve on one piece plate that the plate needs to be modified also.

**RoyE** · 06-04-2020, 04:27 AM

Also I didn't find any water diverters in the block

**mach351** · 06-05-2020, 10:58 AM

I’ve run steel bore motors for years on a 2.4 one piece plate. I’ve always used 1/8” fender washers in the thermostat housings. On cast piston motors I dump the poppet out a 3/8 hose. On forged piston motors I plug the poppet completely. My plate is drystacked and I always run diverters. I also run in 80°+ water all the time.

**Capt.Insane-o** · 06-05-2020, 05:04 PM

Cast piston motor is more forgiving to temps. A forged piston steel sleeved motor needs plate mods to get to 140 degrees

**RoyE** · 06-15-2020, 02:31 PM

Ok thanks for the advice. Good to know as one of my powerheads has forged pistons.
May just swap the 2 piece plate over to avoid any problems in case of forged pistons.

**Capt.Insane-o** · 06-15-2020, 10:53 PM

I have my head held in the fire for the next couple weeks but I'll give a tutorial on it soon.

**rjdubiel** · 06-16-2020, 07:27 AM

http://www.us1.cc/racingcoolingsystem.html

if you have not read this it may help ya some.

**bigboy** · 06-17-2020, 05:57 AM

Modify the 1 piece plate. Create a dump cavity in the plate. Drill a small hole in the water inlet same size as on stock 2 plate.

Only had to remove powerhead 5 times for testing to achieve what I describe here in 2 seconds

**Merc 2.5** · 06-17-2020, 03:43 PM

Originally Posted by bigboy

Modify the 1 piece plate. Create a dump cavity in the plate. Drill a small hole in the water inlet same size as on stock 2 plate.

Only had to remove powerhead 5 times for testing to achieve what I describe here in 2 seconds

That's y I like this place so much. Cause people like u take the time to tell others b4 they try it. Pretty much cuts out all the trial runs or experimenting, and blowed motors from tryin new stuff or mix and matching stuff

**bigboy** · 06-17-2020, 03:52 PM

You are welcome. I should look for pictures. I tried a lot of things without luck. If you copy the waterflow of 2 piece to 1 piece adapter you are all good to go. I also put a elbow next to the cavity and connected this with nother one mounted on adapter a bit lower to cool the tuner. Prob not necessary but might act as silencer to decrease noise.

**RoyE** · 06-21-2020, 08:59 AM

Ok after some reading, I understand that for a 2.4 plate you can leave the holes in the plate as they are, use 1/8" fender washers instead of thermostats, put water diverters in the block and use the poppet dump to regulate temps or block it off completely (exactly as mach351 wrote in his reply).

I wonder why Merc supplied the 7/16" washers with this XR2, no diverters, and poppet dumps through hose.

I'm going to put diverters in when I build this motor and change the washers for ones with smaller holes.
@bigboy why didn't you do a similar setup? But instead chose to mimick a 2 piece plate.

**nitro_rat** · 06-21-2020, 09:49 AM

Merc was constantly fiddling with the cooling system on the V6 throughout the duration of production and sometimes what went out the door was totally dependent on what was available. This applies both to fishing and race motors...

**bigboy** · 06-21-2020, 02:08 PM

Roy, all steel sleeved engines came with the popet and stats so i would think this it mercurys preferred cooling system. Ok the xr2 and some promaxes came with the one piece adapter but those engined and especialy the xr2 were meant to race or run wot most of the time...

On the 200xs they modified the base plate to be able to use the popet and stats. So they also used the poppet and stats on high performance engines at that stage too.