1981 mercruiser 120 Ignition advance seems to be sticking Conversion to electronic?

merc120_81

Petty Officer 3rd Class
Joined
Jun 20, 2011
Messages
92
Hi all.

My ignition timing seems to be possibly hanging.

After running WOT, nd bringing the boat back down, and to neutral, the idle is high.. after a little bit, it settles back down to 750 rpm.

I think the 30 year old springs in the distributer are giving me a little heads up they are getting a bit weak.

Do the conversion kits from Pertronix or hot spark, also replace the advance mechenism?

Or am I looking at going to the Delco HEI Electronic Ignition Kit??

thanks.
 

kenny nunez

Captain
Joined
Jun 20, 2017
Messages
3,056
It is a safe bet that your distributor is worn out. There is only 1 bushing in it and the lower shaft has none . There is a bushing in the block above the oil pump that is also worn. Take the breaker plate off and grab the shaft and you will see a lot of movement. The distributor can be repaired by having a new upper bushing and having a machine shop install a lower one. Then add a Petronics conversion.
 

merc120_81

Petty Officer 3rd Class
Joined
Jun 20, 2011
Messages
92
Kenny,
thanks, I will check for slop. Do you know if advance springs etc, are even available? or does the pntronics conversion, take care of the advance as well? eliminating the mechanical advance?
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Ayuh,...... With the pertronics conversion, the sensor screws to the points plate, so the advance stays mechanical,.....
 

kenny nunez

Captain
Joined
Jun 20, 2017
Messages
3,056
When your remove the breaker plate the inside of the distributor may have shavings from the advance weights scraping the inside of the housing. Sometimes the pins that hold the springs will be loose and it lets the weights go too far. You may have to replace the whole unit. Later model 120-140 s came with an electronic distributor which you can convert to.
 
Top