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Discussion Starter · #1 ·
i'm using a ngk fr4 now also a autolite3926. i will be spraying 150hp i have never used nos before. what plug should i use.

sbc 360ci
12.5to 1 6"rods
holley ported heads
 

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I think that's a hot plug for 12.5:1. I've been running FR5's on a 11.5:1 SBC and even a few times with a 150 shot. I wouldn't do it again but it worked well for an outing. I'm using NGK R5671A-8 for 200 shot and it looked ok but most here will reccomend a R5671A-9 or -10 for that application because they have worked well for a ton of people. I have boxes of 8's 9's and 10's ready for more or less hose. :D

Do some searches for fuel reccomendations also.
 

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Discussion Starter · #3 ·
i havn't sprayed it yet. i have always ran the fr4 or 3926 that was what always worked best. i'm just trying to get a plug in there so when i spray it right.
i would say that my compression is more like 10.5 or 11 because the block has never been decked and the heads are only 65 cc
 

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Maybe the -7 or -8 will work best. 4 steps colder for a 150 shot might even be too much but I've never experienced the bad effects of a plug being too cold.. For me, the -7 looked good at 150 and gave peace of mind over an fr5 with a projected tip.
 
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