Idle timing on Tower of Power

[tonkit]

My seloc manual says initial pickup timing: align marks (on bracket and cover) and adjust throttle lever to just barely touch cam. Set timing to 4*-6* BEFORE TDC which I have done. However the tag on the support cover says idle timing should be 5*-7* AFTER TDC. I have also adjusted the WOT advance to 20* while cranking ( to get 18* while running).
Nothing in my manual that I can find says anything about how to adjust the idle timing. Should this automatically end up at the right spot after the initial pickup timing is set? Do I have to make another adjustment somehow? Should the idle timing be set/checked with the engine running or by cranking it over with the starter?
Can someone please clarify this for me?

Thanks

 

[racerone]

Most confusing topic as usual.------Where the engines idles smoothly does not matter as far as spark timing !-----Idle timing is where throttle plates start to open that does matter.

 

[tonkit]

So.... Should I set timing to 4*-6* Before as per manual? Or should I set to 5*-7* AFTER as per the tag on the motor?

I noticed when doing this that when doing the link and sync, with idle stop screw adjusted so the marks align that when I start the engine the idle is over 1000RPM and needs to be re adjusted to get about 650RPM in gear.
I haven't checked the timing with the engine idling but I doubt if it would change/retard the timing by 11* but maybe that is what happens? It also seems odd to me that idle timing would be AFTER TDC instead of Before TDC.
If anyone has a factory manual for a 1982 115 please see what it says about idle timing and let me know!

Thanks again guys

 

[Chris1956]

A 1982 motor should have ADI ignition with six coils. The correct idle pickup timing spec is 5-7* ATDC, Max spark advance is 21*BTDC.

The distributor motors used the 4-6*BTDC as their idle pickup timing spec.

 

[CharlieB]

It wasn't made clear in the manual. Actual idle timing is adjusted to raise/lower idle speed. It isn't always the same set # from one motor to the next.

The manual is clear what the timing needs to be at the throttle pick-up point. And WOT timing.

Timing is advanced as the throttle moves which raises motor RPM until the linkage gets to the throttle pick-up point. From there on both the throttle plate open and timing continues to advance until max timing. From max timing stop only the throttle continues to open.

So make all linkage adjustments exactly as spelled out in the book. Then start the motor and adjust idle speed using the idle timing stop screw. Forget what the actual number is, it doesn't matter. You will have to readjust idle speed once in the water. The exhaust back-pressure will cause it to change.

Idle mixture screws will need final adjustment also while on the water. You will learn that 'Best Idle IN Gear' is still too lean. It will bog, cough or miss on rapid throttle opening and all idle mixtures will need to be turned out not quite 1/4 turn more than best idle while on the hose before it has enough fuel for a flawless acceleration.

 

[jimmbo]

Good explanation/description of how the throttle linkage works. It should be in the Sticky section

 

[tonkit]

CharlieB,

That is exactly as I suspected... And exactly how I have set my motor up. BUT, I have worked on enough power sport engines in my life that I also have seen the damage that incorrect timing will cause, same with too lean fuel/air mixture.
So I was looking for some confirmation from people with more experience with outboards. And you provided exactly what I was looking for! Also, your explanation was quite impressive.

Thank You!!

 

[tonkit]

OK, now after checking, re-checking, and re-checking again the timing, the idle mixture (in til slightest miss then out till smooth then out another 1/4 turn) and idle speed....my engine still seems to idle roughly. Is that just a trait of this engine? Or am I missing something?

For some history, so far I have:
Rebuilt the fuel pump, rebuilt and cleaned the carbs, cleaned the fuel tank and replaced the pick-up tube, replaced all fuel line from the onboard tank to the fuel enricher and everything in between. New solenoid, new rectifier and new stator. Synced the carb throttle plates. Linked and synced.

When I was talking with tech line about stator issues on of the techs said something about he times his by adjusting the initial timing to where it idles the smoothest. I should have asked more but wasn't thinking about it at the time. If I adjusted the timing at idle to where it ran the best wouldn't that throw it off at the pick-up point?

Should I adjust timing for smoothest running at idle then advance idle stop screw until timing mark is 4*-6* BTDC and then set the carb linkage roller to toughing. Then set WOT timing? Hmmm might work. Am I overthinking this?

 

[tonkit]

A 1982 motor should have ADI ignition with six coils. The correct idle pickup timing spec is 5-7* ATDC, Max spark advance is 21*BTDC.

The distributor motors used the 4-6*BTDC as their idle pickup timing spec.

​I still have my idle pick-up set at the 4-6 degrees with the arrow bracket and the line on the cover aligned (as per the manual). The manual says for the 1982 115hp I6 that the "PRIMARY PICK UP" for the type III ignition is 4-6* BTDC and "MAX TIMING" is 20* BTDC at cranking speed to obtain 18* BTDC at WOT.
Are these incorrect? Maybe that's my problem but my flywheel doesn't even have marks for 5-7* ATDC on it???

WOW what a set-up must have been fun for the techs back-in-the-day!

 

[Chris1956]

Have you set the timing pointer at the .462 inches BTDC?

I had thought all ADI ignitions had the 2-9* ATDC for primary pickup spec. You might check a factory service manual, as your Seloc could be out to lunch.

You do have six coils, right? You are sure the flywheel is not marked with ATDC timing specs? Usually the timing decal has a good range.

 

[tonkit]

Have you set the timing pointer at the .462 inches BTDC?

I had thought all ADI ignitions had the 2-9* ATDC for primary pickup spec. You might check a factory service manual, as your Seloc could be out to lunch.

You do have six coils, right? You are sure the flywheel is not marked with ATDC timing specs? Usually the timing decal has a good range.

Pointer is set to .464 before with same verified on dial indicator on piston #1 (again, set, checked and double checked). I do have ADI with 6 separate coils fed by two switch boxes. But now you have added another new setting (2-9*) that I have never heard of on this motor. In my seloc manual the specs on timing are as listed in post #9. Which is what my engine is currently set to.

I also realize that the seloc manual may be wrong. I actually asked in post #3 if someone with a factory manual for this engine would check it to see what is listed there. But I haven't specifically heard an answer on that one yet.

My flywheel has no decal on it, the marks are etched into the flywheel and are worn and hard to read ( wish I could find a timing decal to put on the flywheel but a search turned up nothing). I do have marks after TDC but they are much further out like about 15 or 20* or so. The fact that I couldn't see any marks in the 5-7* AFTER area and the fact that the chart for my motor in the manual both said BEFORE TDC led me to believe that the 4-6* BTDC was the way to go. I can measure the distance and recreate marks for AFTER if that is indeed the correct setting. Hopefully I will hear from someone with a Mercury factory manual for this motor that will be able to supply the specs listed there.

 

[tonkit]

After looking through the specs for several different engines my SELOC manual shows 4-6* BTDC on all 115 and 90 hp engines for all years listed. The larger engines (above 125 hp) show several with pickup timing AFTER TDC usually around 11*-12* ATDC. My manual doesn't list anything in the 5*-7* ATDC range and I haven't heard from anyone that has a factory Mercury manual.\ so I do not know what the factory manual recommends. I don't know if the front cowl support is even the original one for this engine, so the support and the timing sticker on it could both be from a different motor.

​I'm now thinking that I could set my timing to the 5-7ATDC as an initial pickup setting and then re-set the WOT to 18* BTDC and give it a test run. Since the After setting is far retarded from the BTDC setting that I am using now I doubt that it would cause any harm.

Any thoughts on this plan guys??

 

[tonkit]

For anyone who is interested the actual pickup timing for this engine (1982 115 I6) is 5-7* AFTER TDC

 

[Foxfire180t]

Read the notes in the back of your seloc. Choose carb type and firing order. Its a whole graph of all diff motors serial numbers. All timing specs. Next to yours bet it says see note 2. Go to page note 2 is state primary 6 atdc. 21 max cranking with idle stabilzer disconnected. Also has rpm spec in graph. Study the book. Sorry. Frustrating sometimes to see people not read thoroughly or study the manuals before attempting to repair.

 

[jimmbo]

It'a also frustrating when people don't read the rules and open up an almost two year old thread, and one where the Original Poster hasn't been back here in those two years.