Mercury 1975 Thunderbolt 650 3 Cyl

J

jeanp

Cadet
Joined
Aug 10, 2006
Messages
6
Hi,
After 10 minutes full throthle, The motors have a huge power loss but still runs, I changed the spark plugs, adjusted the Idle Mixture to 1 1/2, works for 1/2 day but the problem comes back. I have noticed that the bottom and top spark plug are ok but the middle one gets wet (gas and oil), If I clean it, I good for another 1/2 day.
Any idea?
 
M

mckeemm

Petty Officer 3rd Class
Joined
May 17, 2006
Messages
98
Re: Mercury 1975 Thunderbolt 650 3 Cyl

Sounds like your losing #2 cyilder when things get hot. Swap two of the coils and see if the problem (wet plug) moves to another cylinder. if it does then change the coil if not, you may be in for a switch box.
 
J

jeanp

Cadet
Joined
Aug 10, 2006
Messages
6
Re: Mercury 1975 Thunderbolt 650 3 Cyl

Will the timing be the same if I change coil #1 and plug it into spark plug #2? Could the switch box also have to do with poor acceleration from stop to plane?
 
J

jeanp

Cadet
Joined
Aug 10, 2006
Messages
6
Re: Mercury 1975 Thunderbolt 650 3 Cyl

Will the timing be the same if I change coil #1 and plug it into spark plug #2? Could the switch box also have to do with poor acceleration from stop to plane?
 
J

jeanp

Cadet
Joined
Aug 10, 2006
Messages
6
Re: Mercury 1975 Thunderbolt 650 3 Cyl

Thanks for the clue! 8)
I found what the problem was but I need more info to adjust it. The problem was the distributor, when accelerating, the distrubutor moves but at Idle, it was already half way. I moved it backwards with the adjustment and it seems much better. How do you sync distributor with gas input through carb perfectly, that is the question... Thanks in advance
 
C

casi77

Petty Officer 2nd Class
Joined
Mar 13, 2006
Messages
122
Re: Mercury 1975 Thunderbolt 650 3 Cyl

i have the same engine.. this happened to me, marina did a link&sync ..and carb adjustment, ran ok after that.
Hope I figure out how to do this link & sync business after I get the manual.. will be needing it sometime!!

jeanp said:
Thanks for the clue! 8)
I found what the problem was but I need more info to adjust it. The problem was the distributor, when accelerating, the distrubutor moves but at Idle, it was already half way. I moved it backwards with the adjustment and it seems much better. How do you sync distributor with gas input through carb perfectly, that is the question... Thanks in advance
Click to expand...
 
C

casi77

Petty Officer 2nd Class
Joined
Mar 13, 2006
Messages
122
Re: Mercury 1975 Thunderbolt 650 3 Cyl

i have the same engine.. this happened to me, marina did a link&sync ..and carb adjustment, ran ok after that.
Hope I figure out how to do this link & sync business after I get the manual.. will be needing it sometime!!

jeanp said:
Thanks for the clue! 8)
I found what the problem was but I need more info to adjust it. The problem was the distributor, when accelerating, the distrubutor moves but at Idle, it was already half way. I moved it backwards with the adjustment and it seems much better. How do you sync distributor with gas input through carb perfectly, that is the question... Thanks in advance
Click to expand...
 
J

jaymasta

Petty Officer 1st Class
Joined
Jul 14, 2006
Messages
236
Re: Mercury 1975 Thunderbolt 650 3 Cyl

hey guys I have this same engine also, and I have been trying to find out what the WOT rpm is, do either of you know, or else what is your WOT rpm and what pitch prop are you running?
 
J

jeanp

Cadet
Joined
Aug 10, 2006
Messages
6
Re: Mercury 1975 Thunderbolt 650 3 Cyl

I have the manual from seloc marine and I did not find any sync and link topic :( If anyone finds the sync settings, let me know
Thanks for your help.
 
J

jeanp

Cadet
Joined
Aug 10, 2006
Messages
6
Re: Mercury 1975 Thunderbolt 650 3 Cyl

I finally found the sync process in the Seloc Manual, it is in the "timing" topic, the only thing missing now, is the timing light that I have to buy!!!

Thanks for your help.
 
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