Carb 2.0L 150 idle setting by timing or blade position? (one more time)

**pcrussell50** · 06-21-2019, 07:38 PM

I know this has been discussed a million times before...

So right now, I have the idle timing set at whatever it is supposed to be in the book. And I have been kinda sorta OK setting idle by setting the throttle butterfly stop. But, and I'm sure this is no surprise to many of you guys, it's difficult and sensitive to set a good stable idle this way. Right now, I have it set super low to where it varies from about 400-600 rpm in gear at idle. Sometimes it dies at this setting unless I bump the blades open a little more... But then it's easy to overshoot and go too high. Really this isn't a problem that ruins my day. I've been slowly tweaking this motor and am seeking a finer and finer state of tune.

I wonder if it's OK to fiddle with the idle timing screw just a little to get the idle where I like it. Or should I leave the timing alone.

Motor leaps up without hesitation to mid-high and runs great.

I have all the extraneous modules removed.

-Peter

**Motv18** · 06-21-2019, 07:57 PM

Is that in the water on dry I like dry 800-100 and wet 600-800 that’s for smooth, but summer high heat 400-600 would be good.

Depends on on where your adjustment is at a 3/4 in out idle screw means add subtract time. A time if screw at 3/4 in out means synch again or add subtract carb.

We we run around all year here so smooth running middle road adjustment saves play days from needing to fix seasonal changes.

**flabum1017** · 06-21-2019, 08:10 PM

I should be able to idle with the blades closed and setting the timing to whatever it likes. Assuming the link and sync and idle circuits are good and adjusted properly.

**pcrussell50** · 06-21-2019, 11:15 PM

Originally Posted by flabum1017

I should be able to idle with the blades closed and setting the timing to whatever it likes. Assuming the link and sync and idle circuits are good and adjusted properly.

Bum, how ya been, mate! You've always been a big help.

I had a link and sync by a local 2.0L racer, Kevin of R&R Prop Shop, so I hope I'm good there. In the mean time, the idle is fixed orifice on this motor.

So I will fiddle with the idle timing screw and see what luck I have. Thanks again.

-Peter

**tlwjkw** · 06-22-2019, 04:27 AM

sounds like ya on tha right track.. idle is set with "timin' only".. thats why they have an "idle circuit" in tha carbs.. forget movin' any of tha mechanical stuff ie: linkage/butterflies etc...

for idle timing you need ta do that on the water, in gear.. forget tha manual numbers.. they jus get ya in tha ball park ona hose.... set fine tunes screws (if its got 'em, if WH's they won't have 'em) as manual says.. put tha boat in tha water in gear and adjust "idle timin' screw only" to get motor ta tha rpm/speed to whatever makes both you and tha motor happy.. do this with motor trimmed level.. you can do this on tha trailer first.. after you do that you can go back and fine tunes with screws if necessary... JAN, almost ALL carbureted mercs don't like long idle periods trimmed all tha way down... will do better at level and/or a touch positive...