Spark plug recommendation

[6valiant9]

I could use some help with finding a good starting point with spark plug choice. The engine is 440 with 10.5:1, kb pistons, comp cam extreme 284, iron heads. ngk are preferred if someone has a part number

thanks guys, just kinda stuck on what to start with

 

[OldmanRick]

I believe the NGK number for regulation hi comp 440's is XR5. They do have iridium plugs listed as XR5IX, but i think they are big bucks. I'm hoping someone will confirm those numbers as i have never used them.

 

[70Duster440]

If NGK is what you're interested in, then look here (lower left corner of first page)

[ame]http://www.ngksparkplugs.com/docs/racingspecs2010.pdf[/ame]

The R5670-5 (#2298) racing plug is equivalent to the XR5 (#3332) standard plug. Either of these would be considered a stock heat range plug for a 440. As you go down the list, you drop in heat range. So, the R5670-6 would be one step colder which would be something to consider as your compression goes up. I think you'd be fine with the stock plug. The racing plug is non-resistor, while the XR5 is a resistor plug.

I run R5670-7 plugs (2 heat ranges cooler than stock) on my blown motor.

 

[6valiant9]

thanks for the part numbers, and i;m running a full msd ignition also

 

[66durgederp]

NGK'S! I switched over from champions and have never looked back. i run v-powers currently, but havent tried the iridiums yet. MSD 6A high vib. blaster coil, 8mm graphite core wires. it starts much faster, idle and throttle response are also much much better.

 

[Babyblue66]

We run a 7 or 8 heat range in ngk. As long as it has the correct length and type of electrode. Cant remember the number right now. 5 is a little hot for my liking. But thats my opinion.