View Full Version : spark plug gap

12-21-2009, 11:29 AM
I bought my new spark plugs and was looking at my Moomba/Indmar manuals which says to use .028 or .03 then I looked at my Clymer manual that had a higher number. Out of the box the plugs are not at moomba spec. Question is, do you guys change the gap to spec or use out of the box?

12-21-2009, 11:41 AM
Always use what Indmar states, afterall they are the experts on the engine. Out of the box gaps are a generic gap.

12-21-2009, 01:33 PM
I don't know the differences in the engine between 2001 and now, but I will tell you that new boats ship with AC 41-993 gapped at .060, and AC MR43LTS gapped at .045 are recommended as less expensive and more durable replacements.

12-21-2009, 05:49 PM
Plugs out of the box need to be checked, there are many that I have found that are not properly gapped.

I would used the Indmar recommended gap of .30, although newer chevy V-8s are being gapped larger.

12-21-2009, 06:22 PM
Your engine is a carb engine, newer ones are fuel injected and have diff plugs and diff gaps. Engine nut could prob go into specifics as to difference in gaps....but i was once told you get a smoother idle with a smaller gap but better bang with a larger gap, but then you may need more power going to the plug, i'm sure someone with more knowledge willchime in. I agree always gapyour plugs that way you know for sure they are all the same and it only takes a minute to do