spark plugs

J Clark · Post by **J Clark** » Thu Oct 08, 09 8:27 pm

I have the same plugs in my motor!

J Clark · Post by **J Clark** » Thu Oct 08, 09 8:53 pm

Got mine off Dave Billadeau, so should be ok!!

Anonymous · Post by **Anonymous** » Thu Oct 08, 09 10:46 pm

Those plugs are too cold & will load up , normal use for those plugs would be high compression motors or mild nitrous/blown use , NGK 6 would be better.

Pete · Post by **Pete** » Thu Oct 08, 09 11:16 pm

I run NGK 6's in my cars - seem to work well all around, even the higher performance stuff. Never had one go off yet... famous last words...

J Clark · Post by **J Clark** » Fri Oct 09, 09 1:51 am

Good point guys!

Any idea what compression you're running with those eddy heads?

Anonymous · Post by **Anonymous** » Fri Oct 09, 09 2:16 am

Different engine combos will require different plugs , you can have two identicle engines (hypotheticle

spelling) that will show different plug readings dependant on the tune up , if one set of plugs from engine 'A' shows it requires a colder plug as opposed to engine 'B' then obviously engine 'A' is in need of a better tune , i run NGK 6 on the 605" with 9.5 CR , although i could get away with #5s dependant on weather conditions , if the engine runs lean , too much spark lead , runs hot , incorrect fuel , then the plug will show a colder one would fair better , but this is'nt always the case , just a band aid , when i run the nitrous i use an NGK -8 , when i eventually step up i will use an even colder plug..........too hot a plug can cause preignition/run on/detonation , so it's pretty important the correct plug is used for the application , this is the reason plug reading is important as it will tell you what the motor wants , you could say it's the next best thing to a chrystal ball.

If ever in doubt always go for the colder plug.

Pete · Post by **Pete** » Fri Oct 09, 09 8:21 am

I was running 12.3:1 on the Indy heads with 6's in; so a fair range of CR.