What type of Spark Plugs and Gap?
 

Just wondering what type of plugs that people are using and what gap. What difference does a bigger or smaller gap make? I pulled my plugs yesterday after fogging the engines and they look good. The gap was .040 on all of them.

I'm using AC/Delco 4's in mine (they were in it when I got the boat). I've put 82 hours on the boat and havn't changed the plugs and they work great. I plan on putting in new plugs after "fire up" in the spring.

My engines are zz502's with bigger cams, Inconel valves, Brodix single plane intakes and 1050 Dominators.

Thanks in advance,

Craig

Re: What type of Spark Plugs and Gap?
 

I've had great results with NGK UR-5's gapped at .035

Ran them all season (110 hrs) never fouled

Re: What type of Spark Plugs and Gap?
 

Tried all the big dollar fancy plugs....Back to AC CR44ts.....No better...No worse..

Re: What type of Spark Plugs and Gap?
 

Presently using Champion RC9YC4. These were the choice of my engine builder.
Nickerson recommends an NGK R5671A-9 for my NA 540 with aluminum heads and 9.2:1 CR.

Re: What type of Spark Plugs and Gap?
 

Have always just used the AC Delco MR43T gapped at .045. Dennis Moore recommended the Champion RV15YC4 gapped at .045 also. I have not tried the Champions but have not had any problems with using the AC Delco's.