commercial v recreational timing on 3 cylinder outboards ?

[phillnjack2]

do commercial outboards have different timing settings to normal recreational engines ?
is this a way to de-tune outboard motors ?
say on a 60hp 3 cylinder rude for example.
my setting are 17 degree btdc for max advance timing.
Would the same engine in commercial spec have the same timing or would it be different to the 17 degree's btdc.

its just a theory I have going on in my head why my engine was so out of spec when timing checked ,
I am wondering if it was set up for commercial use or just set up to deliberately be down on power
(for some strange reason).

phill

 

[emdsapmgr]

Re: commercial v recreational timing on 3 cylinder outboards ?

You'd have to compare the factory service manuals for your specific engine vs a commercial one-based on the model number of it. (not the serial number) Commercial engines are different from consumer engines. They may be lower compression, (or retarded timing) so that they will run on lower octane fuels, typically available overseas. (They also have different lower unit gear ratios) You may want to review the factory timing procedure on yours as stated in their manuals. Many of these engines will gain spark advance as the rpm's increase due to the nature of the ignition system. So the actual (real) timing will creep maybe as much as 3-4 degrees at WOT. A marine tech will compensate for this timing creep when setting the timing. Maybe that's the difference you are seeing.

 

[phillnjack2]

Re: commercial v recreational timing on 3 cylinder outboards ?

that sounds very reasonable answer to my question.
but would the timing be as much as say 5 degree's lower than what it says on the front of the engine airbox ?
I am wondering what damage if any could be caused by retarding the timing 5 degree's /
would it simply be a drop in power ? or could this cause any major damage to piston and bore etc.
also what amount of power drop would 5 degree retarding on max advance cause ?