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Spark Plugs NGKTR6s or 104 autolites?

3K views 7 replies 3 participants last post by  KDB50SS 
#1 ·
I pulled my headers off to recoat them, which plug for NX set up with 100 shot. Maybe 150 max Is there any difference in these two plugs?
 
#2 ·
It depends on your current power output.

With just a stock or bolt-on modded motor, you're ok with either of those plugs up to a 150 shot. They're about the same heat range.
However, they ARE less forgiving if you don't have the tune just right. If you're on the lean side, those projected tip plugs will run too hot and act like a glow plug.
I ran TR6's with the 150 shot on my bolt-on motor for years with no issues.

Now with the heads/cam motor already producing NA power equivalent to the stocker on the 150 shot, I run NGK BR7EF NON-projected tip plugs when I'm playing with the spray on top of it.
 
#3 ·
Its a true 4 bolt main LT4 engine, not just top end, with a cam and ported heads and intake, all bolt ons, with a Mallory Box, Yank 3600ss coverter, GM HD timming chain,with 373 gears,eaton, dennys drive shaft, walbro, FLP transmission vac mod built transmission, ect
The nitrous is just for fun, maybe 10 times a year
 
#4 ·
Its a true 4 bolt main LT4 engine, not just top end, with a cam and ported heads and intake, .....
Taking a wild guess assuming you're about 375 rwhp NA, then I'd run non-projected tip, either BR6 or the BR7's I mentioned.
 
#6 ·
Yes, with NGK's, the higher number indicates a colder plug. The opposite with Autolites.
 
#8 ·
I thought a read some years ago , that the autolites 104 were just a tad shorter for header clearance, I'm running Gen II triys with LT4 heads, angle plugs, so i need all the room I can get. Can anyone recall if this is correct, because I like the NGK's better.
 
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