Spark plugs
Thread Starter
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Fleet Mechanic
Joined: Aug 2010
Posts: 1,574
Likes: 6
From: Cranbrook, Ont., Canada
Spark plugs
Hi all... Ready to install new plugs in my 400. I have raised the compression from the stock to 9.3:1. Should I go a colder plug to stop detonation or is the stock heat range ok. Also... would any of you have a pic of WHERE your coil is mounted on the performer Intake? 
Lead Driver
Joined: Nov 2006
Posts: 5,217
Likes: 506
From: Pa.
If your going over 5000 rpm than drop 2 to 3 heat ranges otherwise maybe drop one ..
What ignition are you running ? If you have a hotter coil and the plug wires to carry the fire then widen the gap ..
If your running "Buzz Box" like MSD, Mallory, Crane or ACCEL etc. with a high-energy coil than this is the rule of thumb:
Up to 10.5:1 .050 to .060
10.5:1 - 13.0:1 .040 to .050
above 13.0:1 .035 to .045.
What ignition are you running ? If you have a hotter coil and the plug wires to carry the fire then widen the gap ..
If your running "Buzz Box" like MSD, Mallory, Crane or ACCEL etc. with a high-energy coil than this is the rule of thumb:
Up to 10.5:1 .050 to .060
10.5:1 - 13.0:1 .040 to .050
above 13.0:1 .035 to .045.
Thread Starter
|
Fleet Mechanic
Joined: Aug 2010
Posts: 1,574
Likes: 6
From: Cranbrook, Ont., Canada
If your going over 5000 rpm than drop 2 to 3 heat ranges otherwise maybe drop one ..
What ignition are you running ? If you have a hotter coil and the plug wires to carry the fire then widen the gap ..
If your running "Buzz Box" like MSD, Mallory, Crane or ACCEL etc. with a high-energy coil than this is the rule of thumb:
Up to 10.5:1 .050 to .060
10.5:1 - 13.0:1 .040 to .050
above 13.0:1 .035 to .045.
What ignition are you running ? If you have a hotter coil and the plug wires to carry the fire then widen the gap ..
If your running "Buzz Box" like MSD, Mallory, Crane or ACCEL etc. with a high-energy coil than this is the rule of thumb:
Up to 10.5:1 .050 to .060
10.5:1 - 13.0:1 .040 to .050
above 13.0:1 .035 to .045.
gonna keep it on file John.
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