just a quick 1
i no there are 2 heads on fe/fc
1 with 5 threads (m14x1.25)=6.25mm thread
1 with 7 threads (m14x1.25)=8.75mm thread
5 thread head use ngk bp4 as standard (use bp5 or bp6 for hot motors)
7 thread head use ngk bp5s (bp6s or bp7s for hot motor)
ive been looking through a few ngk book on number/letter representation
and both the bp4 and bp5s are the same length plug(3/8" 9.5mm), only difference is the electrode thickness on (s) is 2.5mm
ive seen a few running bp5hs (1/2" 12.7mm thread with 2.5mm electrode) on 7 thread heads
Whats people thoughts?
or are the old numbers of bp5s out of date (meant to be 12.7mm thread)
If people arnt sure on p.no
Do they now why there running,
5 thread head 14x1.25 x9.5mm thread
7 thread head 14x1.25x ___mm thread
Another thing are people playing around with the gap on different heat ranges
If been recomemend bp6s plugs with a 0.7-0.8mm gap
When running near stock with twin carbs and extractors
If hot cam bp7s with 0.6-0.7mm
If stock with electronic ignition bp5s 0.8-0.9mm gap
Stock with points bp5s 0.8mm
I was told there us a range for gap as everymotor is different
Just wondering what works for others?