Planing down my head

mncafik

Cadet
Joined
Feb 2, 2004
Messages
20
I have a 1987 70 hp Evinrude, I have been souping her up a bit - New forged pistons, boyesen power reeds - bigger carb jets etc.. I was thinking of getting the head planed down to increase the compression - anybody know how much I can safely shave off?
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: Planing down my head

What you have done are not hop-up mods' you just made the engine do what it was designed for! What type of boat are running?
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Planing down my head

Simply installing "bigger" carb jets may actually hurt your performance, as that may casue the motor to run rich. DEcking the head may help a little, but the 3-cylinder OMCS are already a fairly high compression motor. If you really want to make one sing, you have to think tuning - not bolt-on. I know several people who have worked over OMC triples with good results. Adding bigger carbs is one thing, but what goes in must come out and you must deal with scavenging the exhaust out of the motor, too. Lots of theory involved in exhaust tuners and making them work properly, but that's where the power is...<br />- Scott
 

mncafik

Cadet
Joined
Feb 2, 2004
Messages
20
Re: Planing down my head

Exhaust tuners..hmmm, I will look into that... Thanks for the advice....<br /><br />Mike
 
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