Evinrude 1980 / 85 HP Fast Idle

R

Rapio

Seaman
Joined
Apr 13, 2013
Messages
62
Carbs overhauled and synced both full open and closed. Control cable connected at full closed. Timing checked set at 4 degrees BTDC while running on water muffs. Low RPM is 1200. Not likely to drop to 700 +/- in gear on water. I suspect from reading Evinrude threads, further idle adjustment is done by changing low speed timing. Would someone please confirm this and is the timing retarded (later) or advanced (earlier) to lower RPM. Thanx. PS No, these carbs don't have idle adjustment mechanical or metering and butterfllies are to be fully closed from what I have determined from similar engine threads.
 
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BonairII

BonairII

Commander
Joined
Jun 7, 2011
Messages
2,727
Re: Evinrude 1980 / 85 HP Fast Idle

If you have a large trash can....fill it with water and drop the leg of the motor in it. You'll get a better idea of how much rpm drop you'll get.

Do you have an idle adjustment screw that you can lower idle with?
 
E

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Evinrude 1980 / 85 HP Fast Idle

The rpm's of the engine will go down significantly, once the boat is floating in the water. The fact that the prop exhaust is 20" underwater creates backpressure and slows the idle rpm's. So, you have to set the idle rpm's when the boat is floating normally in the water and it is in forward gear. You can't set it on the trailer. Yes, as you adjust that large screw on the spark advance lever, you will be actually adjusting the idle timing. Don't worry about the degrees of idle timing-set it by the correct rpm's: approx 650-750 rpm's. Each boat is different-transom height, prop pitch, etc.
 
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