[DDorriety]

Hello,

I plan to do a link and sync on my Mercury 150hp Saltwater series
ser#0T468962. It idles a little rough. I have various manuals but none exactly
match this motor. My question is:

1)The Decal on the motor states 4BTDC\20BTDC. Is the 20BTDC timing
Cranking Speed or Wide Open Throttle? Could someone please tell me the
Cranking Speed or Wide Open Throttle timing?


2)I understand that the final idling timing will be set by adjusting the idle RPM in gear in the water. How close to 4BTDC should I expect it to land.

Thanks,
Dennis

[Chris1956]

Dennis, If those specs are correct, they probably refer to idle pickup timing and max timing. Normally you set the carbs to just start to open when timing reaches the idle timing spec, in your case 4*BTDC. You set the max timing adjustment to keep max timing to 20*BTDC. Idle speed is set to 850-950RPM or so, whatever you can get away with.

You will find that max timing will be reached when the throttle is about 2/3 open.

BTW- You might recheck that idle pickup sped. My '93 150HP V6 has a 4*ADTC idle pickup spec.

[DDorriety]

Thanks Chris,

I double checked the decal. It clearly states 4BTDC\20BTDC.

Do you know if the 20BTDC refers to WOT in the water or
could this be set on the trailer turning the starter?

Thanks,
Dennis

[j_martin]

Originally Posted by DDorriety

Thanks Chris,

I double checked the decal. It clearly states 4BTDC\20BTDC.

Do you know if the 20BTDC refers to WOT in the water or
could this be set on the trailer turning the starter?

Thanks,
Dennis

No, the spec is at full timing advance cranking. You actually have an advance module that will advance it a few more degrees at about 5000 rpm.

I'm thinking you have a foreign timing decal on it. 4BTDC sounds off quite a bit for either idle timing or throttle pickup. I would expect it to be about 8ATDC idle timing, and 4ATDC throttle pickup.

You should try to identify the engine more clearly and look up the timing specs for it. They do vary quite widely, especially at the idle end.

hope it helps
John

[DDorriety]

Hello,

Thank you for your response.

The motor is a 2002 Mercury ser#0t468962 150XL

I did notice that the decal numbers 4BTDC\20BTDC is really close to
what in in the attached post.
http://forums.iboats.com/showthread.php?t=168855

Thanks for your help.

Dennis

[Chris1956]

Dennis, I only have the specs for a '97 Merc 150. Do you have ADI or CDM ignition?

1997 Merc 150HP carb V6s with ADI Ignition systems have idle pickup timing of 2-9* ATDC, and max timing to be 21*BTDC. The CDM Ignition V6s vary more, with Max timing specs from 19-27* ATDC, depending on what ECU you have.

[DDorriety]

Hello,

Thanks for the help.

My Motor has CDM ignition.
The control module is an 857185-A1.

I did the link and sync on the trailer. I used a dial indicator and verified the
timing pointer.
I set the idle timing to 4*ATDC and the max timing was at 20*BTDC so I left it alone. At least I think it was 20*BTDC. The 20 timing mark was aligned
with the pointer. I may need to verify if this was BTDC or ATDC.
You made me wonder when I saw your post.

Max timing specs from 19-27* ATDC

Did you mean BTDC?

After doing link and sync on the trailer I backed the boat into the water
first I preformed the De-card procedure with Sea Foam then I
set the idle timing. I adjusted the idle timing to ~950 RPM out of gear and
~650 RPM in gear. I then checked the the idle timing it was at 0 degrees.
It sure did crank and idle much better.

I did not verify the Max timing. When I backed the boat into the water I was not sure it would be safe to run the RPM up with it on the trailer.The river I was at is not big enough to launch the boat. I thought I would check the
max timing next time I go to the lake.

Thanks,
Dennis

[Chris1956]

sorry, I did mean BTDC for the max timing. I can check to see if I have a listing for your ECU. No promises, however

[Chris1956]

Sorry, I do not have a spec for that ECU. Time for you to invest in a Merc Service Manual for your motor.

[DDorriety]

Thanks Chris for your help.
I've ordered a manual that I think may cover this motor.
I'll let you know how it turns out.

Dennis