Cap, Rotor and Spark Plug Wire Replacement

[Split Decision]

My owners manual basically recommends inspecting the above subject items and replacing accordingly.

I have a 2001 328 Four Winns,which is throttle body fuel injected. I boat in fresh water and put about 50 hours a year (six month season) on our 5.7 litre gas engines.

Based on my useage would there be a general rule of thumb for how often you would replace cap and rotor and spark plug wires?

Mike.

 

[j-d]

A dozen years, 600 hours, you're due to at least inspect. Ours didn't get anywhere near that far before it started misfiring. A metallic dust forms and enough will cause misfire. Then if it forms a carbon trace the misfire won't go away.
NAPA had a cap with brass contacts to replace the one we had with aluminum contacts. I'm trusting this is a Delco EST distributor also marketed as Voyager. If so, an automotive (truck) cap and rotor will work and there's no "marine" issue with them.
Be careful, though, if you replace these parts. The center has to have a spring to keep the rotor in contact with the cap. I've seen where sometimes the spring is in the cap, other times where the rotor incorporates the spring. Be sure you have only one of each. Either Cap springy or Rotor springy, not Neither and not Both. My personal preference is a solid contact in the Cap and a springy center contact in the Rotor.
At least in the GM SBC engines MerC uses, the Rotor is LocTite to the distributor shaft and may be hard to get off. I'd rather break the Rotor than risk bending hte shaft or damaging something else in the Distributor.

 

[David M]

It's time.

 

[Split Decision]

Guys, thanks for your replies.

Just to clarify things though, the Cap and Rotor are not the originals. When we purchased this boat three years ago we had the spark plugs, cap and rotor, impellers, bellows, drive oils etc., all changed at that time. Regular routine maintenance including oils, filters etc., take place at lay up in the fall before winterizing.

Being that the Cap and Rotor are now three years old and I'm not sure if the plug wires have been changed before, I was just curious what your thoughts were to a generally acceptable frequency for changing these items (cap, rotor and plug wires) based on my useage as the owners manual was not very specific except to say inspect and go from there.

Thanks,
Mike.

 

[David M]

Rule of thumb I was told years ago was multiply every hour by 100 to get the equal road miles. Remember the road is uphill and in first gear.......always! I.e. 50 hours on oil is the equal of 5000 miles.

Use this change as a benchmark.

My 2 cents!

 

[Sandy]

I think frequency depends a lot on the individual boat and engine/ignition .

With my old engones with points distributors I replaced (gapped)plugs, caps , rotor, points, condensor at least yearly , sometimes more often. When I upgraded those engines to The Delco Voyager EST distributors coils & wires kits, The caps , rotors and plugs seemed to almost never degrade but I'd change every couple years anyway.

Now with newer (2003)blue MPI engines in the boat , I expected very good life out of those same components, but find it necessary to replace caps and rotors at least once a year again and check the distributor-related "cam retard angle" parameter with the TechMate MEFI-4 scan device a few times a season.

At bare minimum, I would suggest check cap & rotor at the beginning of each season and replace if at all deteriorated as part of preventative maintenance. If they are deteriorated, you know to check more often. Scraping or filing off corrosion is not great maintenence. Since plug gaps can change even if all else is good with them, it might be wise to check plugs once a year as well. They are also a good indicator of other issues of which you may not otherwise have been aware. After replacing distributor components, I always check timing on engines that have adjustable timing, and cam retard angle on non-timing-adjustable distributor injected engines.