replacement ignition coil .. which one ? merc 260 thunderbolt iv 5.7L

[otgdy]

I am looking to replace the coil on my 1984 Merc 260 with a thunderbolt iv ignition system. I have been to 3 different places and receive different coils.. with resistor, without resistor, and a hei unit. Can someone please tell me which part number I should order and if it has an external resistor or not ? Is the thunderbolt iv a hei unit ? I picture the coil in the cap as a hei distributor not this... am I correct ?

Thank you
OTG

 

[Bt Doctur]

Re: replacement ignition coil .. which one ? merc 260 thunderbolt iv 5.7L

nope ,looks the same as any coil. 27 7803A 4 1 COIL, IGNITION Thunderbolt systems use a internal resistor type coil.Full 12v is applied to the coil. manual 3 in here
http://boatinfo.no/lib/library.html

 

[Bondo]

Re: replacement ignition coil .. which one ? merc 260 thunderbolt iv 5.7L

I am looking to replace the coil on my 1984 Merc 260 with a thunderbolt iv ignition system. I have been to 3 different places and receive different coils.. with resistor, without resistor, and a hei unit. Can someone please tell me which part number I should order and if it has an external resistor or not ? Is the thunderbolt iv a hei unit ? I picture the coil in the cap as a hei distributor not this... am I correct ?

Thank you
OTG

Ayuh,.... I gotta ask, Why,..??

 

[otgdy]

Re: replacement ignition coil .. which one ? merc 260 thunderbolt iv 5.7L

Ayuh,.... I gotta ask, Why,..??

Why am I collecting coils ? or why am I even looking for a coil ?

Guess i am looking because I made it 100 yards out of Metapeake boat ramp and the engine died and would not restart or cough with ether. Took it home and it started fine a little while later. Idles like a dream. Next time I went out it wouldn't go into gear without the engine stalling. New carb,cap,wires,rotor,no water in gas,timing spot on. I read a thread where someone is running a thunderbolt iv with a non-internal resistor coil and was wondering if I had too much resistance in the circuit.. line+coil. Guess not by this feedback.

Can I put a chevy hei distributor on this engine and be legal ? Please no feedback about how great etc etc etc the thunderbolt iv is.

OTG

 

[Bondo]

Re: replacement ignition coil .. which one ? merc 260 thunderbolt iv 5.7L

Why am I collecting coils ? or why am I even looking for a coil ?

Guess i am looking because I made it 100 yards out of Metapeake boat ramp and the engine died and would not restart or cough with ether. Took it home and it started fine a little while later. Idles like a dream. Next time I went out it wouldn't go into gear without the engine stalling. New carb,cap,wires,rotor,no water in gas,timing spot on. I read a thread where someone is running a thunderbolt iv with a non-internal resistor coil and was wondering if I had too much resistance in the circuit.. line+coil. Guess not by this feedback.

Can I put a chevy hei distributor on this engine and be legal ? Please no feedback about how great etc etc etc the thunderbolt iv is.

OTG

Ayuh,.... A GM HEI is Not ignition protected, 'n is Not a marine ignition system,....

There's a diagnostic tree in Don'S Adults Only section at the top of the forum,...

while the T-Bolt IV is a Great system, the odds are yer problem Ain't the coil, but something else,...

Btw,... If it's stallin' as ya shift into gear, it's More Likely yer lower shift cable is bindin', than the coil bein' bad,...

 

[otgdy]

Re: replacement ignition coil .. which one ? merc 260 thunderbolt iv 5.7L

Ayuh,.... A GM HEI is Not ignition protected, 'n is Not a marine ignition system,....

There's a diagnostic tree in Don'S Adults Only section at the top of the forum,...

while the T-Bolt IV is a Great system, the odds are yer problem Ain't the coil, but something else,...

Btw,... If it's stallin' as ya shift into gear, it's More Likely yer lower shift cable is bindin', than the coil bein' bad,...

I agree 100 percent. Only problem is .. all of the cables have been replaced and checked numerous times by different mechanics.Cable wouldn't cause it to die after warming up and cruising a few hundred yards. Actually had it running for a few hours (last year) after the cables were replaced. Only problem was it wouldn't/couldn't go over 3000 rpm. Would stall if pushed over 3k. Replaced the carb+fuel pump and did a major tuneup. Runs great on muffs.

BTW: This story has been ongoing for almost 2 years.

Thanks for the link RE: Diagnostic tree. Will check it out again.

OTG

 

[81 Checkmate]

Re: replacement ignition coil .. which one ? merc 260 thunderbolt iv 5.7L

I had the same issue a few years back........1986 thunderbolt iv system..........it would start and idle all day long, as soon as you reved it past 2500 - 3000 rpm it stumbled and sputterd...i checked everything..replaced everything... did the diagnostic tree...still no change.

So i took out the system and replaced with my other boat's ignition system (points) and it ran like a champ... No issues.... So i went with a whole new system....I went with a mallory marine unit off e-bay, It is the pointless system, all electronic....it came with dist,cap/rotor, and wires.

Some on here have used the delco est system from michigan motors... I just didnt like it personally, it's just that I have used mallory equipment in the past and have had good luck with it.

Thought i would throw it out there....Good Luck!

 

[otgdy]

Re: replacement ignition coil .. which one ? merc 260 thunderbolt iv 5.7L

I had the same issue a few years back........1986 thunderbolt iv system..........it would start and idle all day long, as soon as you reved it past 2500 - 3000 rpm it stumbled and sputterd...i checked everything..replaced everything... did the diagnostic tree...still no change.

So i took out the system and replaced with my other boat's ignition system (points) and it ran like a champ... No issues.... So i went with a whole new system....I went with a mallory marine unit off e-bay, It is the pointless system, all electronic....it came with dist,cap/rotor, and wires.

Some on here have used the delco est system from michigan motors... I just didnt like it personally, it's just that I have used mallory equipment in the past and have had good luck with it.

Thought i would throw it out there....Good Luck!

Thanks I appreciate the feedback. Have to check out the alternatives. Going out again this weekend hopefully it will not be in 3ft swells like the last time allowing me to triple check everything again.

OTG