Questions after new distributor trigger replaced

tavacska

Petty Officer 1st Class
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Jan 21, 2017
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244
It's a 1977 mercury in line 6 cylinder.
I replaced a new CDI trigger for the old dead one. It runs good and idle no gear @1000rpm in water tank. Idle in forward gear @600-800rpm in water tank.

But after the replacement, when I tried to relink and resync, I found out that I have to reset the primary pick-up. It is quite some relocation 5-10 degree clockwise, not only primary pick-up, but also second pick-up, max spark position, and idle too.

My question is:

1. What is the reason for this? I am sure the procedure is right for both the old one and the new CDI replacement. The primary pick up is 5 deg, and the max spark is 21 deg. The hardware, which is pick up triangle part, is at the same location of both the trigger. Is that because of the trigger mechanism changed? or because the magnetic point at the new triangle is located differently?

2. Dose this change affect the spark arc transfer inside the distributor house? I am saying this, because the whole house has to be set 5-10 degrees clockwise. The rotor point may miss the pointers of the distributor. And the idle screw has to screw in a lot (almost to its limit) to set the idle limit position. The idle screw and the block bar has a sharp degree contact, which I am afraid is not efficient.
 

tavacska

Petty Officer 1st Class
Joined
Jan 21, 2017
Messages
244
This is what I did for the sync and link for the trigger and carb.

1. Set the degree pointer according to the 0.464 rule from the manual.
2. Set the crank wheel to 5 BTDC. Rotate the distributor to see the spark of the #1. That location will be the primary pick up.
3. Set the crank wheel to 21 BTDC. Rotate the distributor to see the spark of the #1. That location will be the max spark position.
4. The max spark position is also the secondary pick up position.
5. Put the motor to water tank. After warming up, set the idle speed @800-1000, geared @600-800. Readjust the carb idle screw to smooth the motor.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Unless CDI calls for something else, the Mercury timing directions should be followed. After the timing pointer is set to .464 inches BTDC, the motor should be set at TDC and the distributor pulley should have the cast arrow pointing at the dot on the flywheel. If it is not, it explains your timing issues.

All timing should be set with a timing light, right?
 

Chris1956

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Mar 25, 2004
Messages
27,036
One more thing...you do know to rotate the brass collar on the distributor to set the primary timing for carb opening, right?
 

tavacska

Petty Officer 1st Class
Joined
Jan 21, 2017
Messages
244
One more thing...you do know to rotate the brass collar on the distributor to set the primary timing for carb opening, right?
Yes, I did set the primary timing.

And I find out the problem. The new trigger has a tooth different with the old one. I set the one tooth different on the crank - trigger sync and everything keeps the same as the old one.
 

tavacska

Petty Officer 1st Class
Joined
Jan 21, 2017
Messages
244
Unless CDI calls for something else, the Mercury timing directions should be followed. After the timing pointer is set to .464 inches BTDC, the motor should be set at TDC and the distributor pulley should have the cast arrow pointing at the dot on the flywheel. If it is not, it explains your timing issues.

All timing should be set with a timing light, right?


Yeah, I did it with timing light.
it turn outs to be one tooth difference in the end. With one tooth difference, I can still sync everything including primary, secondary, and max spark. It runs good, but the trigger has to be turned 15 deg position.

I don't know why there was one tooth different, because I marked everything as before.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Merc cites the one tooth difference as well. Sometimes (everytime on my motor), the correct cast arrow pointing direction was in the center of the timing belt teeth. Merc says that when this happens turn the belt 1/2 tooth one way (forget which way) to get the correct timing.
 
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