Does anyone know what the factory idle rpm is supposed to be on a 1981 Mercury Inline 6 90HP? It is currently set to 800 RPM and it stalls a lot and has hesitation with the first little bit of acceleration. I tried Google and searching this forum, no luck yet. Any help would be appreciated.
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Murcury Inline 6 Factory Idle RPM
- Thread starter rickvi
- Start date
DropTop5.0
Well-known member
Mine liked to be around 1050 which is a bit high. There is a sync procedure out there by Wayne Canino on IBoats.com.
wired
Well-known member
800 RPM but that is with the idle screws out as fat as you can stand and the idle timing advanced enough to keep it at 800. Fatter the better on the idle screws. There is no transition circuit so the idle circuit has to move it to the main circuit on its own.
two turns out is a good starting point.
two turns out is a good starting point.
The factory spec on the ADI (Alternator Driven Ignition) engines (1980-1988) is 600-700 RPM IN GEAR.
Hestiation on acceleration usually means the idle is adjusted too lean, if the engine is in otherwise good condition.
A weak idle and failure to hold the 600-700 idle, with constant die out when shifting, even though the engine is properly adjusted and with good compression, can be an indication of worn reeds, which of course means an engine tear-down.
A large differential between neutral idle and in-gear idle can also be a bad reed symptom. Ideal is an 800 RPM neutral, and 600 RPM in gear.
Hestiation on acceleration usually means the idle is adjusted too lean, if the engine is in otherwise good condition.
A weak idle and failure to hold the 600-700 idle, with constant die out when shifting, even though the engine is properly adjusted and with good compression, can be an indication of worn reeds, which of course means an engine tear-down.
A large differential between neutral idle and in-gear idle can also be a bad reed symptom. Ideal is an 800 RPM neutral, and 600 RPM in gear.
Bill Gohr
Active member
Yes hesitation is a lean issue or incorrect sync and link, if your carbs haven't been done lately you shoul go through them, especially if the linkages and timing are correct, generally on the hose you set theidle at 1100, when it goes in the water it should lose a 100 or so, then in gear it should be 750 to 850