Parts ordering & delivery

Tired to have to replace my belts twice a season, I decided it was time to fix this recurring alternator belt issue. The PO installed an alternator too big for my M25XPB engine. So after some research and a lot of help from Mainsail on Catalina 36 forum and on I decided it was time to start with this project!

Pulled the trigger and I bought a Balmar regulator MC-614H and an alternator CMI-105-ER on

  • CMI-105-ER – 105A Motorola/Prestolite/ Leece-Neville Externally Regulated Alternator
  • Balmar Regulator MC-614H
  • ​​Balmar MC-TS-A Alternator Temperature Sensor

Very happy with Rod customer service during the decision process and the very fast delivery.

Replacing old with new!

Where do I put the mc-614 regulator?

As soon as I received all parts, the first question was to decide where to put the regulator. I decided to take advantage of the space available on aft of the engine, against the central water tank. Another option was to put the regulator on the port side of the engine bulkhead.

CMI Alternator fitting issue?

As soon as the regulator situation was fixed, I realized the alternator didn’t fit as expected. Time for a quick conversation with Rod @ marine how-to, I can’t say enough how helpful Rod has been in the success of this project). Rod explained me I was able to make one of the alternator bolt shorter, 30 seconds with the dremel and I was good for the next step!

Alternator adjustable arm grinding

Next issue πŸ™‚ After a quick grinding, it fits perfectly!

Broken bolt πŸ™

Almost too easy! The alternator arm decided to break inside the engine block, after some clean up and rethreading, I was able to get a new bolt in.

Back on track. Let’s wire!

Maintenance switch?

Negative bus bar setup

Which belt?

After few tests, it looks like the 17420 is a good fit! Time to order a couple of them for spare.

Ready for testing?

Configure the Balmar mc-614

The tuning of the Balmar MC-614 is pretty challenging, I just followed RC recommendations for your alternator and your battery. You can find everything about Balmar Tuning in the article below.

Why no RPM?

Checking the RPM, I realized it was not showing up, after a bit more help from Rod I started a quick troubleshooting session to realize one fuse failed during the setup.


5 days cruise update

The week-end of Thanksgiving was a perfect time to validate the new alternator setup. Everything worked as expected! Next step upgrade our battery bank for our next long cruise to Catalina.

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