Wanted: Omc 25 H.p. Racing Head

[DonChicho]

i´m Looking For A Hi-performance Head For A 25h.p., Omc, 1999, 2 Cyl.
To Be Used With A-v Gas.

Or If Somebody Know How Much I Can Shave To Be Used With The Aviation Fuel And 30 Degrees.

Thanks,
Don:d

[RichardKCMo]

SayWhat!!!

I guess-HEH HEh you missed this earlier, i'm sure some one knows where to point you HEH,HEH.

RichardKCMo

[DonChicho]

Hope So !!

Don

[johnsonm50]

The only hi performance parts Ive found for a big block 25 are Second Effort made [I think] solid motor mounts. The heads can be milled alot, dont know the max # but do know this will net better acceleration more than top speed. 30 degrees is good, my fastest ones at 29.

[DonChicho]

YEAP!!, THERE IS A HI-PERF. HEAD FROM SECOND EFFORT ( I HAVE A CATALOG WITH THE PART # ).
ARE THIS TOY ARE AVAILABLE ?

ACTUALLY I SHAVED A STOCK ONE ( .020"), UP THE MAIN FUEL JET ( DON´T REMEMBER THE #) ONE # , OPEN THE SPARK PLUG GAP TO .039" ( QL77JC4), AND 30 DEGREEES MAX. TIMING, USING A PENNZOIL 100% SYNTHETIC OIL AT 40/1.....................
AND GAIN 2 MPH .

I WOULD LIKE TO SHAVE THE HEAD A LITTLE BID MORE, BUT....,
BUT REALLY I DON´T KNOW. THAT´S WHY I PREFFERED TO BUY ONE, IF POSSIBLE, FROM THE OLD FACTORY OMC , SECOND EFFORT ONE.

DOES SOMEBODY KNOW IF THERE IS A THIN HEAD GASKET AVAILABLE ?

REGARDS,
DON

[johnsonm50]

If you find a hi perf head Id like one too.

[johnsonm50]

YEAP!!, THERE IS A HI-PERF. HEAD FROM SECOND EFFORT ( I HAVE A CATALOG WITH THE PART # ).
ARE THIS TOY ARE AVAILABLE ?

ACTUALLY I SHAVED A STOCK ONE ( .020"), UP THE MAIN FUEL JET ( DON´T REMEMBER THE #) ONE # , OPEN THE SPARK PLUG GAP TO .039" ( QL77JC4), AND 30 DEGREEES MAX. TIMING, USING A PENNZOIL 100% SYNTHETIC OIL AT 40/1.....................
AND GAIN 2 MPH .

I WOULD LIKE TO SHAVE THE HEAD A LITTLE BID MORE, BUT....,
BUT REALLY I DON´T KNOW. THAT´S WHY I PREFFERED TO BUY ONE, IF POSSIBLE, FROM THE OLD FACTORY OMC , SECOND EFFORT ONE.

DOES SOMEBODY KNOW IF THERE IS A THIN HEAD GASKET AVAILABLE ?

REGARDS,
DON

There are more than one gasket, origional OMC, new replacement OMC & Sierra. Doubt theres a difference tho. One thing Ive run into is if you bore your cylinders the pistons might tag the head at the edges so the head needs to be trimmed a little too. [This was on a head that had been sanded down significantly]. You could probably go 20 or 30 more off the head you have. Seriously tho if you find Second Effort parts available still, post the info. The normal plug gap on these is 30 thou. Why 38? [inquiring minds that want to go faster need to know ] Mike

[Skoontz]

Those tolerances were fairly inconsistent. We once took .1 off a 25HP head and had to use a Dremel on the corners of the head, where deflector was closest.

If you want to save the cost of buying a head, use modeling clay to check the distances between the head and the piston at TDC and mike it. The other thing you could do is get a piece of the softest lead you can find, crazy glue it to the top of the deflector, then carefully bring the piston to TDC. When it begins to retract, that lead will have been compressed and it is easier to mike then the clay. Do that and it will tell you what distances you have to play with.

[DonChicho]

What About Maintain The Squish Band Of .35 "( Or Something Around ???) To Avoid Detonation

I Tested With 39 Gap ( Champion Ql7jc4) And Noted The Punch .
Does Somebody Used An Iridium Plug ?

I´ll Shave Another 20 Thou. An See :d

I Friend Cuted My Stock Flywheel And Look Very Small , Like A Mexican Tortilla ( Cut About 3 Pounds !).

Regards.

[johnsonm50]

What About Maintain The Squish Band Of .35 "( Or Something Around ???) To Avoid Detonation

I Tested With 39 Gap ( Champion Ql7jc4) And Noted The Punch .
Does Somebody Used An Iridium Plug ?

I´ll Shave Another 20 Thou. An See :d

I Friend Cuted My Stock Flywheel And Look Very Small , Like A Mexican Tortilla ( Cut About 3 Pounds !).

Regards.

Don, If you remember we talked over on BRF, I cut a flywheel too & was strongly advised against it. I put a regular one back on and didnt see a performance boost anyway. It seems the way these are cast that the outer part is where most of the strength is. I hope if you decide to keep it on that you have a good scattershield. A light wheel is another thing that will net more acceleration than speed. I just remove the steel rings from mine, you dont get much weight loss from shaved aluminum unless you remove alot.

[DonChicho]

UNTIL NOW....., II´M STILL RUNNING THAT MINI FLYWHEEL WITHOUT ANY PROBLEM .

DOES SOMEBODY MAKE A CARB VELOCITY STACK FOR THAT PONNY ?

DON

[Skoontz]

Cutting flywheels

If you cut a flywheel, make some type of shatter shield like bell housing on a car or wrap the motor hood with a transmission blanket so if it scatters the shrapnal is stopped by the blanket...

[DonChicho]

Until Now!............ Maybe, I´m So Lucky !!....:d