1971 Flatback Re-power question

[wdbeyer]

First post here.  Have a '71 Flatback that is in need of a re-power.  Currently running a tired '87 Merc 150 magnum.  Thinking that a used 200 hp two-stroke might be the way to go.  We did a cosmetic overhaul on the boat five years ago, but planning a complete rebuild this winter (floors, transom, console, etc.)  I'd like to close the transom in and do a porta bracket or bracket/jack[plate at that time.

What is the concensus on the Flatback community?  200 hp?  What shaft length?

Thanks in advance.

Wayne

[RickK]

Over the past 14 years it seems a 150 is the max you want to put on a FB - we've seen as high as 225 but they said it was too squirrelly at speed.  Remember that when the FB hits a quartering wave sometimes it has a mind of it's own and may take a hard right on you or worse on you, so you don't want to not have control at 40+ mph. The FB was originally designed for twin 70s or a 90. A 90 moves the FB along nicely for 1 or 2 people. If you are going to guide in it, use a 150.

[GoneFission]

I'm pretty sure the Mariner 15- Mag is a 2.5 liter engine.  The same basic engine was made in 200 and 225, so going to a 200 would not be a big difference.  Weight could be an issue, as the 2.5 liter Merc/Mariner was right around 400 lbs depending on leg length.  The 20" was just under 400 and the 25 was around 420 or so. 

Merc does not sell 2-strokes  any more, so you are looking a a 4-stroke V-6 at 175HP and around 470 lbs in the Mercury line.  Suzuki's 4 cylinder 175/200 line is over 500 lbs, as are the 4-cylinder Yamaha 175/200 models.  The Evinrude E-Tec 150 is a nice V-6 2-stroke that comes in at 418 lbs. and would be a nice choice for your boat.  You would likely have to change controls for the E-Tec, but the Mercury could use the same throttle and shift controls.  No oil tank for a 4-stroke either. 

IMHO - the E-tec or the Merc would be good choices for your boat.  Another choice would be to find a last-year Merc Optimax 150 somewhere.  These are going for good prices now as close-outs, and most dealers will throw in a 5 year warranty with them as well.  The Optimax 150 is a 2-stroke V-6 and weighs almost the same as your Mariner at 420 lbs. and uses the same controls and oil tank.   

Hope this helps - good luck!