looper tuner

[Leon]

I just redid my old 16' Checmate Tri-Mate by adding a 12" pad, a manual Bob's Machine Jackplate w/ 4" set back, dual steering, the works. With the '91 Evinrude 225, 20" looper without low water pickup it went from 61mph to 72mph (6300rpm {rev. limiter kicked in}, 25" 4-blade prop).
I tried a 27" OMC SRX Chopper but could even get it above 5800 rpm when the engine started hesitating. I thought it was a fuel problem but couldn't find anything. Tried the 25", again 6300 rpm, then the 27" , 5800. The engine height was not changed (can go maybe 1/2 higher). Suggestions please?
I feel I should be able to get more out of this. This motor pushed an HST to 85MPH before.

[Flat Out]

Leon , Try a raker 26 maybe. That hull is going to need some lift. The SRX is not a bow lifting prop. How high is your motor jacked. Sounds like you've done a ton of work that has made a huge diffrence.:)

[Leon]

:) Sean, thanks for the reply.
yes I did quite some work on this old lady.
the motor is set with the shaft approx 2" below the pad, jackplate at its highest, but can go up one more hole.
any suggestions for an electric fuel pumpthat I should use?
I have a feeling the motor isn't getting enough fuel with the pump I'm using now.

[Flat Out]

Raise the motor another hole if possible. If you are running the oil injection(VRO) you have to use the factory fuel pump. In good working order this pump should provide enough fuel at hi RPM. Keep an eye on TEMP & PRESS guages. How is the fuel quality down there? HI air temp will definately have adverse effect on performance. :cool:

[Leon]

:p I'm running pre-mix with an electric pump only. all VRO-parts removed.
Air temp here is average of 90 year round.
Fuel quality ok.
I'll try the 26 Raker you suggested after I raise the engine some more. Do you really think with the weight of this engine that I need to raise the bow anymore? The boat is only 16'.
Nice to know there are still some OMC users :D

[Flat Out]

You may be right as far as bow lift is concerned. A friend of mine, Glenn on the board has had good luck with a Holley blue pump on a 78 175 Merc. Try as many props as you can get your hands on. You never know what will work until you try.:D

[Markus]

Most people successfully use Holley pumps.

I use a Carter pump and that seems to work too.