Anyone had any issues with GPS or Depth Gauge interference with non-resistor plugs? Found this on NGK's site, so that's why I'm asking.

"NGK strongly recommends using resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance. This is because resistor spark plugs reduce electromagnetic interference with on-board electronics.

They are also recommended on any vehicle that has other on-board electronic systems such as engine-management computers, two-way radios, GPS systems, depth finders or whenever recommended by the manufacturer."

Is there a particular reason that the non-resistor racing series plug is recommended with the AFR heads, versus a plug with the same reach and heat range that might be more readily available?

Tom,

Go with a Champion
RC 12 YC
RC 14 YC_(Hotter)

or cross reference to you brand of choice.

Bob

I have never had any issues with non resistor racing plugs. No interference with my stereo system, my GPS chartplotter, MSD or Crane Ignition boxes, etc.

Is there any reason you don't want to run the spark plug AFR recommends? From what I see on their website, they recommend an Autolite 3935. That is a non resistor, non projected tip, copper racing plug.

Hey MT, I was just mostly going by Bob's recommendations. I figured the plug recommended by AFR on their site is for automotive applications, which may differ from marine. I was concerned about radio interference with the non-RF plug because we run with the stereo on frequently, use the VHF radio, and I have a depth gauge with the transducer right under the motor. I didn't want to install a set of $4 plugs in each hole only to find that they cause me problems and will have to be switched out. The RC12YC's that Bob recommended with his most recent post are actually a resistor plug that is available almost anywhere for around $2.00, but they ARE a projected tip plug. I noticed that you mentioned that you don't like to run a projected tip plug in a marine engine - is that due to concerns about detonation, or is there some other reason?

I too run with the stereo, chart plotter, etc going. I buy my NGK racing plugs from o'reilly's or rockauto for under 2 bucks each. I don't care for projected tip plugs because of the constant load high cylinder temps we see in boats. I don't like any detonation or hot spots , they ruin your good time lol

Something to think about. Guys will install super low 50 ohm per foot plug wires . A 5k ohm resister in the spark plug kinds defeats the idea of comparing a 50 ohm per foot msd plug wire compared to a standard automotive off the shelf wire. Will any of that really matter as far as power goes, not really. Just a thought.

I don't think you will have any issues with radio noise unless you are running solid core wires