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I have a SNS 3 cam and prc 225 heads 62cc. car at cruising I get some random knock every once in a while. I’ve done some digging and seems that my tr55s may actually be a bit hot and I should be using a tr6 plugs with my added H.P. and with my calculations I’m at around 11:1 compression. The problem is I search and get conflicting information on this for the tr6 plugs. Any thoughts on this and what gap size do you recommend? Car is currently awaiting a mwc 9 inch and I’m just itching to do some wrench turning on the bird so figured I’d get into something
Okay my cam is 235/243 and using the mls gaskets with a slightly bigger chamber. My tuner was also pat g maybe I will contact him and ask his thoughts. Was just wondering others thoughts as well as I’ve seen a lot of conflicting info. Thanks
I use Autolite 5245s for an OE motor. For motors with detonation problems, use 5243s. For extreme cases (as in nitrous) or FI, use AR103s. The motor runs smooth on these plugs. Set them at .40. These plugs can be had in standard copper core, single platinum, double platinum, and iridium. If your motor tends to eat plugs try the single platinum, P5243. Stay away from the doubles and the iridiums. They cost more and do not dissipate the heat as well.
NGK recommends to drop one heat range for every 100 hp added to the stock setup. The TR55 is a wide gap plug. If you look at the chart below, you will find the first number "5" is the heat range and the second "5" is the wider gap. The TR6 will do two things, first the "6" is one heat range cooler. Second, the missing second number indicates the smaller gap. So the equivalent small gap plugs would be the TR5 and TR6. I would definitely drop to the TR6 with your setup.
Last edited by vettenuts; May 25, 2019 at 07:08 AM.
NGK recommends to drop one heat range for every 100 hp added to the stock setup. The TR55 is a wide gap plug. If you look at the chart below, you will find the first number "5" is the heat range and the second "5" is the wider gap. The TR6 will do two things, first the "6" is one heat range cooler. Second, the missing second number indicates the smaller gap. So the equivalent small gap plugs would be the TR5 and TR6. I would definitely drop to the TR6 with your setup.
By that chart and that most of us run .040 N/A, looks like we should be running TR5's instead of 55's on stock motors. Are those even a thing?
And by the chart looks like a TR6 would be a slightly colder .040 gap plug. Perfect.
By that chart and that most of us run .040 N/A, looks like we should be running TR5's instead of 55's on stock motors. Are those even a thing?
And by the chart looks like a TR6 would be a slightly colder .040 gap plug. Perfect.
Awesome thanks for posting that man...
Yes, you can buy TR5 spark plugs. I have seen a lot of guys buy TR55's and then re-gap when the TR5 is actually the plug they need out of the box. But the TR55 has an "internet" history so that's what a lot of people buy without further research.
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Ls1 plugs 
