Which idle sounds better? First or second vid?

[FstaRockr Burns]

3cyl 60hp dual carb..

First after getting boat:

Then after syncing carbs and fudging with timing etc.. I did set a bit high cos haven't been on the water yet..

Haven't set idle timing, haven't made it to water yet.. Second is smooth but is it better?

Thanks

Still not 100% sure about primary pickup, manual is a bit confusing, anyway hope this runs smooth!

 

[fastjeff]

Being very familiar with that motor, I can tell you that adjusting the idle can only be done in gear, warmed up (and then add another 1/2 turn OUT). Timing has nothing to do with idling, by the way, just WOT operation.

Jeff

 

[FstaRockr Burns]

Being very familiar with that motor, I can tell you that adjusting the idle can only be done in gear, warmed up (and then add another 1/2 turn OUT). Timing has nothing to do with idling, by the way, just WOT operation.

Jeff

Hi Jeff, thanks. I've linked the max wot stop so the butterflies are at 90 at wot and the stop. I've also used the piston stop method to determine true tdc.. I then set cranking timing at 28 as per the manual.

Could you perhaps run me thru primary pickup setup? I read idle is set by timing on this motor? If not could you give me a run thru of the correct method?

Motor starts very easily FYI so no immediate problems..gave carbs a real good clean and 1 1/2 turns out on each mix screw..

Would I set the idle timing advance in neutral or gear? As mentioned the manual has no idle spark spec, only rpm figure..

Tx

 

[fastjeff]

I set mine at 21.5 to 22 degrees at full throttle with a light. (Don't know where you got 28 degrees, but that will fry pistons.) With today's crappy gas, the 23 degrees Merc recommends is risky. I reduce it a bit 'cause I'm sick for replacing burnt pistons, especially the top one.

Remove the top carbs cam lever so you can hold the motor wide open (only 3,000 rpm) and set the timing. Then hook the cam back up.

On idle adjustments, that "1 1/2" turns is just preliminary. You have to adjust the carbs, in gear, motor fully warmed up. Take your time--that's the worse engine going to set an idle on!--and get your best idle. Go from one carb to the other until it's the best you can get. Then add 1/2 turn OUT (CCW) on both and LIVE with the idle you get. If not, it'll bog like crazy when you throttle up.

The spark and the carbs should be wide open at WOT throttle, but I force the carbs to open as late as possible, with near full spark advance before they open. That reduces bogging, which these motors tend to do.

Jeff

 

[FstaRockr Burns]

tx fastjeff - I was going to double check the timing on the water at wot anyway - my manual clearly states "Due to the nature of this ignition system - a cranking advance of 18 will yield 23 at WOT / 5300rpm".


See the pics on timing for my motor:





I was thinking of setting the adv down a degree or two as well cos of the newer fuels - ill do that on the water.. Ill see how to open carbs as late as possible.. i thought the primary pickup was not adjustable but i see there is a lock nut to adjust.. ill leave it as is and see how it runs and go from there..