25 OMC mod

[bfitz]

25 Mod guys-
curious to know..what's a good redline for these engines?
do you use props specific to the OMC or can you use a B-mod or C-stock prop.?..
does the engine have any preferences regarding fuel octane, fuel brand, or oil type?

I looking for a baseline so I can know if I'm going in the right direction.
Thanks

[Eric Engler]

It should like 25XS and B MOD HotRod Props.

[Appraiser25US]

25 Mod OMC Data

bfitz,

Here is the data from my experience with the 25 OMC. The "Tiny Tach" reading is close to 7500 RPM`s. @ WOT. Prop selection can change this reading, but typically this is close to the Maximum and continue to stay together.
I have found that my best B Hot Rod props used on the 25 Mod to be a bit small for the average size race courses. Depending on set up, a Mercury, C Mod prop used with a 16-21 Mercury gearfoot works well. I`m not familar with the Yamato C class prop combinations.
Racing fuel with Pennsoil synthetic oil in an 8 -1 ratio always passes the fuel tests, even though I`m not sure the higher octane is needed or even an advantage. Never sure what oxygenating compunds, Ethanol, or other additives are present in pump gas blends ( APBA designates a legal local fuel source near the race site).
Other 25 OMC drivers may have different opinion. Best of luck with the OMC 25 project.
Ron Whittaker 25Y

[STEVE FRENCH]

Brian,

My "BEST" wheel that I ran with you in B-MOD / Whitney point 2004, is a old Hopkins "mouse-ear" 7 1/4"X14 C-MOD 16/21 ratio- wheel that I got from David L-6.

I will have my 2003 short tower motor avail to try if you want to try it at; Franklin, Warren, Loch Haven, Williams port, Waterford Ont, Franklin MOD NATS, Crystal Lake, Hanawa Falls.

Hope to see ya out there----IN MY WAKE!!!!

19P