My 1984 Sea Ray part verification please

[mrstevewayne]

My project boat is a 1984 Sea Ray with a Mercruiser 260 engine. I ordered a new coil and points for the electrical system from NAPA auto parts. The coil is made by Sierra Company, and is part number 18-5438. It says on the box “Replaces Mercruiser 392-7803A4”.
It says on the coil the following: “use with external resistor” then below it says “Use of resistor required if used on Non-Thunderbolt Ignition system”
My question is how can I tell which ignition system I have, and where is this External Resistor they are talking about?
Thank you in advance for your comments

 

[tpenfield]

Welcome to iBoats . . .

Have the Moderators move this post to the Mercruiser section for better responses.

Your serial number of the engine will help in determining proper part selection.

 

[Scott Danforth]

My project boat is a 1984 Sea Ray with a Mercruiser 260 engine. I ordered a new coil and points for the electrical system from NAPA auto parts. The coil is made by Sierra Company, and is part number 18-5438. It says on the box “Replaces Mercruiser 392-7803A4”.
It says on the coil the following: “use with external resistor” then below it says “Use of resistor required if used on Non-Thunderbolt Ignition system”
My question is how can I tell which ignition system I have, and where is this External Resistor they are talking about?
Thank you in advance for your comments

welcome aboard.

your wiring harness would have a resistor wire in it for the coil . if you have points, you have a non-thunderbolt ignition.

 

[achris]

1984 Mercruiser 260 should not have points. All (from 1982) were delivered with TB-IV.

Chris......

 

[dubs283]

My question is how can I tell which ignition system I have, and where is this External Resistor they are talking about?

If you remove the dist cap and look there will either be a points set/condenser under a standard rotor or there will be an electronic hall effect sensor and a rotor with a metal ring that has gaps in it much like a castle nut.

It's possible you have either, that was a time when t bolt was becoming much more common though boat manufacturers may have had some older engines in stocks they were still using.

If you post a picture of the inside of the distributor many here can tell you very quickly what you have.

As stated, if your ignition system is conventional and has the oem harness the external resistor is in the wire harness

 

[QBhoy]

I’d take a guess that this is referring to the resistor that similar (slightly older) engines with the same part would have. Like the Volvo Penta AQ271 for example.