Reading spark plugs

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ok so I looked in the ngk book and here is what I found.
The gr4gp has a 14/19mm (3/4) reach with a 20.6 (13/16) hex
The fr4gp has a 14/19mm (3/4) reach with a 16mm (5/8) 8 hex.
Both plugs will work but the fr4gp has a smaller hex and therefore easier to fit with headers.
R=resistor 4= heat range 4 being the hottest GP=Platinum Firewire (6mm)
 
res1vw21 said:
ok so I looked in the ngk book and here is what I found.
The gr4gp has a 14/19mm (3/4) reach with a 20.6 (13/16) hex
The fr4gp has a 14/19mm (3/4) reach with a 16mm (5/8) 8 hex.
Both plugs will work but the fr4gp has a smaller hex and therefore easier to fit with headers.
R=resistor 4= heat range 4 being the hottest GP=Platinum Firewire (6mm)
Click to expand...

Ah...I.C. so I with Magnum heads and 1 for LA heads.
 
Thanks again guys, Is there some info on which main jets math to secondary jet sizes? Kind of the way you need to match the metering rods? And if a olug is too hot, what should i do? is that a timing issue? Im running 34 degrees @ 2500rpms.....

maybe i need to adjust the vacuum advance...
 
If a plug is too hot then all you need to do is change it to a colder plug in the same family. Been a long time and I'm sure someone will correct me if I've got it backwards, but most domestic type plugs it means subtracting a number from it to get a colder plug. Autolite 66 would be a 65 colder. NGK it is the other way around from what I remember. If you get, for example a BPR5ES plug and need a colder one you would want a BPR6ES. I'm just using a number I remember and not a MOPAR related number. Just an example for you.

You need to have your mix and timing set right to really know where you are on heat range and then start adjusting if needed.
 
MoparBrit said:
If a plug is too hot then all you need to do is change it to a colder plug in the same family. Been a long time and I'm sure someone will correct me if I've got it backwards, but most domestic type plugs it means subtracting a number from it to get a colder plug. Autolite 66 would be a 65 colder. NGK it is the other way around from what I remember. If you get, for example a BPR5ES plug and need a colder one you would want a BPR6ES. I'm just using a number I remember and not a MOPAR related number. Just an example for you.

You need to have your mix and timing set right to really know where you are on heat range and then start adjusting if needed.
Click to expand...

yep you are correct. the bpr5es is a small engine plug like a lawnmower if irc.
 
ramcharger said:
Wrong! I may be old, and I may be a mechanic but I'm not dumb. You've got it backwards kid: http://www.4secondsflat.com/Spark_plug_reading.html
Click to expand...




Well, I guess the two older gentlemen that told me this are backwards. One night in the pits at Ascot Park in the 80's C.R. Axtell and Ed Iskyderian explained many things to me including how to read a sparkplug. There are some things in life that you never forget especially when talking to some of the heaviest hitters in motor sports. I looked at some of the other articles and have concluded that anybody can post anything on the interent without any actual proof. I especially liked the one where this guy tells you what kind of engine it is by looking at the sparkplug. I wonder, can he also tell you if a tail light is out?:cheers:
 
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