Spark plug selection
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
According to Jacobs Electronics' Tech manual, a copper core plug is the best all around plug to use for N/A engines used on the street. He recommends different tip lengths for force fed engines like yours.
It probably is a good idea for you to order a copy because it contains tons of ignition info. There's an entire section on plugs.
Jacobs says Autolites give the longest life because of the material used in the electrode doesn't wear away as quickly.
I've tried several different plugs and just a couple of days ago installed a set of AC FR3LS gapped at .035.
I removed a set of platinum tipped jobs which were one heat range hotter than the 3LS's because they appeared to be running a tad too hot; very little color.
Heat range is something you'll have to play with because the correct range depends on lots of variables - compression ratio, spark curve, initial advance setting, A/F ratio, etc.
I haven't played with different gap settings yet because I'm still running the stock coil/distributor setup.
Your setup is a lot more radical than mine so my plug experience won't apply to you.
One trick I intend to try soon is to cut back the rotor tip 1/8" to increase the spark energy delivered to the plug.
Hope this little info helps. Hopefully some others will chime in.
Jake
It probably is a good idea for you to order a copy because it contains tons of ignition info. There's an entire section on plugs.
Jacobs says Autolites give the longest life because of the material used in the electrode doesn't wear away as quickly.
I've tried several different plugs and just a couple of days ago installed a set of AC FR3LS gapped at .035.
I removed a set of platinum tipped jobs which were one heat range hotter than the 3LS's because they appeared to be running a tad too hot; very little color.
Heat range is something you'll have to play with because the correct range depends on lots of variables - compression ratio, spark curve, initial advance setting, A/F ratio, etc.
I haven't played with different gap settings yet because I'm still running the stock coil/distributor setup.
Your setup is a lot more radical than mine so my plug experience won't apply to you.
One trick I intend to try soon is to cut back the rotor tip 1/8" to increase the spark energy delivered to the plug.
Hope this little info helps. Hopefully some others will chime in.
Jake
