Modded Engine Spark Plugs
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Modded Engine Spark Plugs Just picked up an LS1 Z28 with the mods in signature. Car has been stored and driven very little for past 11 years. It runs good and was tuned years ago. I’m new to the LS1 scene but have only used AC Delco plugs in other GM vehicles. Other brands have given me issues. With the mods below, can someone suggest a good plug and gap setting? Going to pull a plug soon to see what’s in there.
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Great, thanks for the info. Those TR55’s do seem popular. Are those the iridium or just copper? I’ve always ran regular old AC Delco plugs with good results but I think I’ll give the TR55’s a try.
If it were me I'd go a step colder and go with a TR6. You are right at that threshold for a colder plug, and going with something like a TR6 will give you more of a cushion. That's just my opinion
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After doing a ton of reading and research, I have been leaning towards the TR6’s. I’ve been weary of NGK plugs since putting them in an 04 GMC 5.3 and it ran like crap. Put AC’s in and it ran like a champ. I’ll probably go with the TR6’s and do some MSD wires while I’m at it.
After doing a ton of reading and research, I have been leaning towards the TR6’s. I’ve been weary of NGK plugs since putting them in an 04 GMC 5.3 and it ran like crap. Put AC’s in and it ran like a champ. I’ll probably go with the TR6’s and do some MSD wires while I’m at it.
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A little insight on spark plugs. The larger gaps (.60 for instance) are harder on the coils. The coil has to wind up a nano second longer to jump the bigger gap. The current coils are about 25K volts. The older coils and truck coils are/were about 31k. The drop to .40 is because of the drop in voltage. Fifty is OK, but is a little harder on an OE 25K coil.
Second, I have used Autolite plugs in all my vehicles for decades. The AR 103 is a great racing plug. For your application I would recommend 5245s in standard heat range or 5243s if you want a colder plug. These plugs are available as standard copper, single platinum tip (center electrode), double platinum tip, or iridium under the above heat range numbers. Remember, for Autolite, Champion, and AC plugs, the higher number indicates heat range increase while the lower number indicates a cooler plug, which is the opposite of Asian NGKs.
Second, I have used Autolite plugs in all my vehicles for decades. The AR 103 is a great racing plug. For your application I would recommend 5245s in standard heat range or 5243s if you want a colder plug. These plugs are available as standard copper, single platinum tip (center electrode), double platinum tip, or iridium under the above heat range numbers. Remember, for Autolite, Champion, and AC plugs, the higher number indicates heat range increase while the lower number indicates a cooler plug, which is the opposite of Asian NGKs.
Thread Starter
Teching In
Joined: Oct 2017
Posts: 32
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From: Massachusetts
A little insight on spark plugs. The larger gaps (.60 for instance) are harder on the coils. The coil has to wind up a nano second longer to jump the bigger gap. The current coils are about 25K volts. The older coils and truck coils are/were about 31k. The drop to .40 is because of the drop in voltage. Fifty is OK, but is a little harder on an OE 25K coil.
Second, I have used Autolite plugs in all my vehicles for decades. The AR 103 is a great racing plug. For your application I would recommend 5245s in standard heat range or 5243s if you want a colder plug. These plugs are available as standard copper, single platinum tip (center electrode), double platinum tip, or iridium under the above heat range numbers. Remember, for Autolite, Champion, and AC plugs, the higher number indicates heat range increase while the lower number indicates a cooler plug, which is the opposite of Asian NGKs.
Second, I have used Autolite plugs in all my vehicles for decades. The AR 103 is a great racing plug. For your application I would recommend 5245s in standard heat range or 5243s if you want a colder plug. These plugs are available as standard copper, single platinum tip (center electrode), double platinum tip, or iridium under the above heat range numbers. Remember, for Autolite, Champion, and AC plugs, the higher number indicates heat range increase while the lower number indicates a cooler plug, which is the opposite of Asian NGKs.
IIRC GM put out a TSB saying to gap them at .045 instead of .060
If you go with the stock heat range I'd get the TR5's because they can be gapped smaller. You can use the TR55's but they are designed for the larger gap and you have to bend the electrode down quite a bit to get to .045.
If you decide to go with the TR6's you won't have any problems.
If you go with the stock heat range I'd get the TR5's because they can be gapped smaller. You can use the TR55's but they are designed for the larger gap and you have to bend the electrode down quite a bit to get to .045.
If you decide to go with the TR6's you won't have any problems.
definitely agree. You at at the crossroads between a TR55 and a TR6. I would lean towards the colder plug as well. .045 gap is a good number.
Yes. The OE coils (25 K volt) can handle that. At .60 you need a truck coil to jump that gap safely. Also, I am not sold on the NGK or Accel V and U grooves. Its a marketing strategy with little if any increase in performance. The AR 103s are cut back plugs which offer a larger flame kernel and are cooler which are good for FI or NO motors, but not necessary for you.
Last edited by rednari2; May 16, 2018 at 11:14 PM.