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2014 Mercruiser 377 MAG Spark Plug Gap

J

jon_allen

Regular Contributor
Hi All.

I have twin 2014 377 Mag motors with cat. converters.

The decal on the flame arrestor cover states that the proper spark plug is an AC 41-101

The decal states a gap of .040 in.

This seems odd to me as most 377 motors using 41-101 plugs with a flat cap HVS distributor are generally set at .060 in.

What gap is correct?

I am concerned because 1 motor is displaying a misfire fault after I replaced the plugs which I set at .060 as well as a new cap and rotor..

Any help would be appreciated.

Thanks

Jon Allen
 
o2batsea said:
Why would you not set it to what the engine manufacturer says? Do you know something they don't?
Click to expand...

Hi

The AC 41-101 iridium plug comes pre gapped @ .060.

It is not advisable to change the gap on a pre gapped Iridium plug.

Some Mercruiser printed info states the gap to be .060 for a 2014 377 Mag with Delco Hvs ignition.

A revision perhaps?

Just trying to get it right.

Jon Allen
 
Plugs are not pre-gapped...They are close.

You can adjust the gap on an Iridium Plug. Do not wedge your gap tool against the electrode to increase the gap. Your plug gap tool has a small hole for bending the ground strap away from the electrode.


Adjust the plugs to the spec on the engine. Merc now recommends NGK ITR4A15
 
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