which ecm/pcm best for marine conversion

This is my first post to this board so I would first like to say thanks to all the knowledgeable people out there who have contributed. I am starting a GM tbi conversion on my 94 ski nautique boat (351W). Here is my question. I have access to a free 16168625 pcm with harness TB and all sensors. Or I can purchase a 1227747 ecm and all needed items at the local JY for around $250. Is it worth trying to tune around the lack of VSS signal in a boat or should I stick with the 1227747 set up for simplicity. Just for the record I'm new to the tuning process it will all be a learning curve. Thanks in advance for any help I may receive.

The 1227747 is a good TBI computer for a Marine application. The 1227747 is well supported, and affordable. For a first time tuning experience, the '7747 is a very good choice. Many members here, origianlly started with the 1227747.

dave w

Just thought I would post the first few pics of my 16168625 PCM to ford marine conversion. I did get lots of advice pointing me in the direction of other pn ecms but in the end I could not pass up this entire tbi system that was donated to me by a good friend.
First job was to de-pin the connectors and remove all un used wires and splice together a temporary harness. After that came the scary job of removing the stock chip from the memcal and soldering in a socket in its place. Also made an aldl cable per the diy instructions on this sight using this part off E-bay (FT232RL 3.3V 5.5V FTDI USB to TTL Serial Adapter For Arduino Mini Port N137).
Attachment 14151

One problem I did encounter was the drawing from the 16168625 PCM page on this site seems to have the fuel pump wires labeled backwards (F6,B12) also the abcd pin labels on the IAC are mis labeled. This drawing worked for my application and may be worth looking into if you encounter the same problems.Attachment 14152

I fabricated a intake spacer and O2 spacer from 1" 6061-t6 plate off E-bay. Just used the holley gasket and tbi gasket to lay out the holes on the intake spacer and used the exhaust riser gasket to machine the required openings in the exhaust spacer.Attachment 14153Attachment 14154

you can convert a ford duraspark distributor to work by removing the flyweights and tack welding the upper and lower shafts together in the fly weight retracted stop position. When you remove the vac advance lock the pickup coil to the plate in the "no vac applied" position. I believe this should give the proper phasing pickup to rotor. If not I will repost later findings.Attachment 14155

Last items were mounting the coil, stock ignition pickup, and e2000 ford fuel pump on brackets that I made or modified.Attachment 14156Attachment 14156Attachment 14157

At last it starts, idles, revs up and data logs on the garden hose!!!!!!!! Thanks to all the info on this site....
When my programmer arrives later this week I will start the next learning curve.. How to tune a chip for this application. Any thoughts on what to disable or zero out on my first bin file?

Just thought I would add one last post to this thread. The boat is up and running well after a day or two of adjusting the ve tables. I decided on a complete open loop tune because it provided a much smoother idle and mid-range. Also required 19 lbs of fuel pressure to feed this engine at high power settings!

I wonder how the 16168625 determines Near Idle vs. Off Idle fuel and spark tables without a VSS?

dave w