re-build question!~

[rockets 86]

I have a 97 200 Merc EFI. Who would build me the fastest, baddest undercover Merc on the planet? She's an 83 Enchanter and I want her to be a sleeper. It's going to along winter here in Frostbite Falls and I need a project! Any O/B builders give me a shout!

 

[keit29]

From someone who has been there. Just find a drop on promax 225 powerhead for a lake motor or a drop on 260 or 280 head if you want all out speed and more maintenance.

 

[wired]

Nuts. The '97 200 EFI has the same ports as the 225 pro max. There are a few minor differences between the two. Keep in mind that a 225 promax has closer to 250 HP from Mercury.

1. The 225 uses a 7 petal front end with fiber reeds and a matching 7 petal intake. The 200 block can be used with a 225 front end or a 240 sport jet front . Both come up on the market time to time for $250 ish plus $100 for the manifold.

2. The injection controller is different 200 vs 225 but unless you can get a rare A-6 or a more common A-32 go with a Brucatto box. Avoid the most common A-17 like the plague. WAY too lean. Runs great until you melt a piston. The injection box is the same.

3. That leaves the 260 exhaust plate. You find them for $100 or so.

So you get all your parts together . Change the rod bolts, weight match the rods, bore the block closest oversize to use Vertex pistons. Dont let anyone try to sell you 225 spec pistons with thin rings. They make no difference and you end up having to use unnecessary thick pin washers. Just get the 200 spec pistons.
Shave the heads for 34 CC chamber size. That will get you 140 or so PSI compression and you'll need premium gas.
Jim Ruck retired recently but Ron Mandanz is running Jims shop and he does good work. Have him bore the block, cut the heads, do a light cut on the exhaust chest to free up the breathing and cut the lower exhaust port to 225/260 specs along with a rod slot cut . You'll need to open up the exhaust plate to match. Use a bridgeport tuner. Use metal cage rod bearings.

In all it will cost you under $2000 parts and machine work included ( not including the ECU ) and it will run up to 7200 before you'll want to lay off with just about any prop you put on it.

Its a good feeling turning a 32 pitch prop at 7200 RPM.

 

[keit29]

Didn't the 225 promax sleeves differ from the 200? Mine is a 95, so maybe it's different to the 97. Also, when you go from the 7 petal front from the 5 isn't the 5 good under 7500?

 

[wired]

Didn't the 225 promax sleeves differ from the 200? Mine is a 95, so maybe it's different to the 97. Also, when you go from the 7 petal front from the 5 isn't the 5 good under 7500?

225 Pro max and 200 sleeves are the same '95 on. Only difference inside the cylinders being the rod slots on the 225 and they are cut after the sleeves are installed. The 7 petal reeds are good for 200-300 RPM with the same prop over 6500 RPM or so. The 4/5 petal reeds will work but there is a very noticeable difference in top end power with the 7 petal configuration. The 4/5 petals work better with carbs to be sure on the low end but the EFI doesnt care one way or the other.

Even with a 30-32 pitch prop I pop right onto plane and am going 70 MPH before I get a chance to look down.