Forward Gear Idle position vs Neutral?

[jbutler67]

Tuning the idle for new carburetor. Starting with idle speed screw 2 turns in after just resting on the idle cam. Also, starting with idle mixture 1 1/4 turns out from seated. After reaching normal operating temperature, I’ll disconnect the throttle cable from the carb. The next step isn’t clear to me.

Manual notes that before beginning to adjust the idle speed screw:
“Shift drive into Forward gear, at idle”.

Another manual notes, “place in forward gear, idle position”

My question - What’s the difference between “Neutral” and “Forward gear, at idle”?



(Note: I will remember to ground the ignition timing lead, to force the ignition module into base timing mode. )


1998 Mercruiser 5.7 with 2 bbl Mercarb and Thunderbolt V ignition.

 

[HT32BSX115]

My question - What’s the difference between “Neutral” and “Forward gear, at idle”?

Howdy,

It assumes you're in the water. making the engine "loaded"

 

[Bt Doctur]

get it running and up to temperature, adjust mix screws for the highest rpm, readjust idle speed to 750ish on land
put in water, shift into fwd, adjust idle speed

(Note: I will remember to ground the ignition timing lead, to force the ignition module into base timing mode. )

Why, are you adjusting the timing?

 

[jbutler67]

(Note: I will remember to ground the ignition timing lead, to force the ignition module into base timing mode. )

Why, are you adjusting the timing?

That is step #2, according to the Seloc manual.

 

[havoc_squad]

I would ditch that SELOC manual and go to www.boatinfo.no and print to PDF the Mercruiser OEM manual using a PC or laptop that supports Flash.

Save it on like Google drive and just print off the pages you want in print.

OEM manual + free = Win.

If you want a printed OEM manual, see if iBoats has it for purchase.

 

[jbutler67]

Thanks, all.

Does that mean there is no need to ground the ignition timing lead when tuning the carb idle speed and mixture? (and that the Seloc manual is wrong :embarassed: ... lol)

 

[Bondo]

Thanks, all.

Does that mean there is no need to ground the ignition timing lead when tuning the carb idle speed and mixture? (and that the Seloc manual is wrong :embarassed: ... lol)

Nope,.....

 

[jbutler67]

I came across this item regarding the Thunderbolt 5 Ignition Module.
http://www.boatfix.com/merc/Bullet/94/94_02.pdf

This seems to imply it IS necessary to lock it in Base Timing Mode even when adjusting idle RPM speed or idle mix?

 

[HT32BSX115]

Thanks, all.

Does that mean there is no need to ground the ignition timing lead when tuning the carb idle speed and mixture? (and that the Seloc manual is wrong :embarassed: ... lol)

You do place the ignition system into "BASE TIMING" mode when setting the idle.

He meant that you should ditch the SELOC manual in general. There's enough cases where Seloc and Clymer (or other) manuals either have misprints or have been flat wrong and/or confusing that most of us are just not willing to trust them anymore.

The Mercruiser, Volvo, or OMC (OEM) manuals are (in general) never wrong and most of us don't want to screw up a repair because the manual got it wrong.

I'm not in the boat repair business, but if I was I wouldn't take a chance with NON-OEM manuals. And since OEM doesn't cost all that much, I'm not taking a chance working on my own boat either..........

Just saying.

Regards,

Rick