Distributor Upgrade

[brodie123]

Hi All;

A couple quick questions. I'm upgrading my Mercruiser 3.7 L4, 224 I/O from points to electronic ignition. The manual shows a resistor wire - I normally would be looking for a ceramic resistor for the voltage drop. Where is this wire exactly and is it actually a high resistance wire? How do I best by-pass it?

Also, my merc manual calls for 6 degrees BTDC. The label on the engine clearly says 8. Can I safely assume the label on the engine (valve cover) to be correct? It all looks original and all the other specs are correct. (valve cover is original)

thx!!!

 

[JonBrown]

Hello brodie,
2 degrees isn't that much of a difference although I have seen this such as a California boat has different timing than a Texas boat. Due to fuel availability and or emissions. Follow the label. You may have a 12 volt system and that would not have a resistor in line. Just check your coil + and point - and if it is 12 volt it is probably without.
If it has a resistor it will be 6 volt to your coil/point . Electronic is 12volts and the coil will have to be a 12 volt coil. Hope this helps..
Jon

 

[bruceb58]

The resistor is a resistor wire..not ceramic.

 

[Rick Stephens]

You can tap into the purple wire before the added resistor wire and bypass the resistor.

 

[Davetowz]

Timing spec was changed. Fuel quality sucks anymore and mercruiser changed the spec . I run mine at 6 and have had no issues. A quick search here will give you many posts regarding timing on the 470 variants. The resistor is a wire ( purple) running from the choke heater to the coil +. Make sure that you want to bypass the resistor wire bfefore you do it. If using a pertronix module the instructions are pretty clear. Can tap in before the purple wire for key on batt voltage for the module +. Make sure you dont reverse polarize the module... It won't take it for even a moment, I did, and replaced the module.

 

[brodie123]

Thank you! There is indeed 6V on the coil and I ordered a new coil along with the dist upgrade. thx!!

 

[bruceb58]

Thank you! There is indeed 6V on the coil and I ordered a new coil along with the dist upgrade. thx!!

Why get a new coil?

You got thrown a curve in a previous response. Keep the coil you have along with its resistance wire and just make sure the Pertronix module gets a full 12V before the resistor wire.

Look at this document at part B
http://www.pertronix.com/docs/instru...heets/1141.pdf