Spark plug thread
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
Spark plug thread
At great risk of starting a "forum fire," I'm looking for advice on spark plugs. I've checked the search engine, for what it's worth, and have found almost nothing of any value.
Bought the car 4 months ago with 63k on it. Runs just fine and got 29 MPG on a Montana road trip (one stretch it hit 32!). It's 21 years old, and I haven't checked them yet (I'd bet they've never been changed).
Car is stock except for mufflers and a K&N. What should I get <ducks head>?
Bought the car 4 months ago with 63k on it. Runs just fine and got 29 MPG on a Montana road trip (one stretch it hit 32!). It's 21 years old, and I haven't checked them yet (I'd bet they've never been changed).
Car is stock except for mufflers and a K&N. What should I get <ducks head>?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
DAMN,, That one is easy. DO NOT OVER THINK spark plugs and or wires!!. The ONLY reason the auto manufactures use platinum/iridium (rare metal spark plugs) is so the engine retains the factory emissions parameters for the requires warranty mileage.
Just get the OEM AC Delco plugs that came with it and drive on. The $50 each fancy dancey silver core plugs will NOT make ANY DIFFERENCE. Neither will the $400 sparkplug wire sets or the $130 each coils. LOL!
GM did a really good job on the LS series secondary ignition system.
UNLESS you have some fire eating mega dollar race engine, plugs and wires are NOT the place to invest tons of dollars into.
GM Makes a GM Performance RED plug wire. Its high QUALITY, fits properly, spiral wound core and it NOT expensive. Get the GM performance plug wires, OEM Platinum/iridium plugs and you will be very happy.. I think they are around $60 a set. If you cheep out and buy the off the shelf crap automotive store box set of wires, you will later kick your self in the ****. They will NOT last very long. There are other aftermarket plug wires and different plugs that will also works just fine. Some other plugs that work: AUTOLITE, NGK, ect..
Bill
Just get the OEM AC Delco plugs that came with it and drive on. The $50 each fancy dancey silver core plugs will NOT make ANY DIFFERENCE. Neither will the $400 sparkplug wire sets or the $130 each coils. LOL!
GM did a really good job on the LS series secondary ignition system.
UNLESS you have some fire eating mega dollar race engine, plugs and wires are NOT the place to invest tons of dollars into.
GM Makes a GM Performance RED plug wire. Its high QUALITY, fits properly, spiral wound core and it NOT expensive. Get the GM performance plug wires, OEM Platinum/iridium plugs and you will be very happy.. I think they are around $60 a set. If you cheep out and buy the off the shelf crap automotive store box set of wires, you will later kick your self in the ****. They will NOT last very long. There are other aftermarket plug wires and different plugs that will also works just fine. Some other plugs that work: AUTOLITE, NGK, ect..
Bill
Last edited by Bill Curlee; Aug 2, 2018 at 03:59 PM.
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
DAMN,, That one is easy. DO NOT OVER THINK spark plugs and or wires!!. The ONLY reason the auto manufactures use platinum (rare metal spark plugs) is so the engine retains the factory emissions parameters for the requires warranty mileage.
Just get the OEM AC Delco plugs that came with it and drive on. The $50 each fancy dancey silver core plugs will NOT make ANY DIFFERENCE. Neither will the $400 sparkplug wire sets or the $130 each coils. LOL!
GM did a really good job on the LS series secondary ignition system.
UNLESS you have some fire eating mega dollar race engine, plugs and wires are NOT the place to invest tons of dollars into.
GM Makes a GM Performance RED plug wire. Its high QUALITY, fits properly, spiral wound core and it NOT expensive. Get the GM performance plug wires, OEM Platinum plugs and you will be very happy!,
Bill
Just get the OEM AC Delco plugs that came with it and drive on. The $50 each fancy dancey silver core plugs will NOT make ANY DIFFERENCE. Neither will the $400 sparkplug wire sets or the $130 each coils. LOL!
GM did a really good job on the LS series secondary ignition system.
UNLESS you have some fire eating mega dollar race engine, plugs and wires are NOT the place to invest tons of dollars into.
GM Makes a GM Performance RED plug wire. Its high QUALITY, fits properly, spiral wound core and it NOT expensive. Get the GM performance plug wires, OEM Platinum plugs and you will be very happy!,
Bill
Le Mans Master
Joined: Sep 2014
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From: Kelowna BC
Acct Suspended APR 2026 by request
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2020 Corvette of the Year Finalist (performance mods)
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I agree with Bill... you don't need the super expensive fancy plugs just stick with a reputable brand and you will be fine, my car does just fine with $2 a piece ngk's haha... oem, ngk, or denso would be my choices... those msd coils are a huge waste of money... the ignition systems on these cars are pretty good and the only reason you would need more out of it is when you get to the point that the coils can no longer supply enough to effectively jump the plug gap and that point will far surpass what most people will do with the car
Last edited by StingrayRebel; Aug 2, 2018 at 06:21 PM.
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
I have decided that I'm going with Denso Iridium TT plugs from Rock Auto, about $48 delivered. I can get the Delco Platinums for $33 delivered. Delco Iridiums are $42 delivered. I have had good experiences with Denso plugs, and certainly with Delcos,. The prices are all close enough not to make a difference,.
Tonight I'll pull off three or four plugs and wires to see how bad they are, measuring the wires for resistance. I DO get quite a bit of radio noise that I would not have expected. Maybe my wires are shot? I am owner number 5 of this car, the prior owner being 75~ years old and driving the car only 4,000 miles in 14 years. I drive it daily, and have put 6,000 miles on it since March, including an 1,800 mile road trip about 2 weeks ago - the car performed flawlessly and returned nearly 29 miles per gallon on the highway.
The plugs could be originals or could have been replaced. The wire set is red in color - no markings. Were the originals red?
Tonight I'll pull off three or four plugs and wires to see how bad they are, measuring the wires for resistance. I DO get quite a bit of radio noise that I would not have expected. Maybe my wires are shot? I am owner number 5 of this car, the prior owner being 75~ years old and driving the car only 4,000 miles in 14 years. I drive it daily, and have put 6,000 miles on it since March, including an 1,800 mile road trip about 2 weeks ago - the car performed flawlessly and returned nearly 29 miles per gallon on the highway.
The plugs could be originals or could have been replaced. The wire set is red in color - no markings. Were the originals red?
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Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I have decided that I'm going with Denso Iridium TT plugs from Rock Auto, about $48 delivered. I can get the Delco Platinums for $33 delivered. Delco Iridiums are $42 delivered. I have had good experiences with Denso plugs, and certainly with Delcos,. The prices are all close enough not to make a difference,.
Tonight I'll pull off three or four plugs and wires to see how bad they are, measuring the wires for resistance. I DO get quite a bit of radio noise that I would not have expected. Maybe my wires are shot? I am owner number 5 of this car, the prior owner being 75~ years old and driving the car only 4,000 miles in 14 years. I drive it daily, and have put 6,000 miles on it since March, including an 1,800 mile road trip about 2 weeks ago - the car performed flawlessly and returned nearly 29 miles per gallon on the highway.
The plugs could be originals or could have been replaced. The wire set is red in color - no markings. Were the originals red?
Tonight I'll pull off three or four plugs and wires to see how bad they are, measuring the wires for resistance. I DO get quite a bit of radio noise that I would not have expected. Maybe my wires are shot? I am owner number 5 of this car, the prior owner being 75~ years old and driving the car only 4,000 miles in 14 years. I drive it daily, and have put 6,000 miles on it since March, including an 1,800 mile road trip about 2 weeks ago - the car performed flawlessly and returned nearly 29 miles per gallon on the highway.
The plugs could be originals or could have been replaced. The wire set is red in color - no markings. Were the originals red?
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
I've pulled off #3, #5, and #7 (boy, THAT one was no picnic) and discovered I have something called "Nowlogy Hot Wires." My plugs are "Siverstone Berus," whatever in the hell that is. Wire resistance is 422 ohms on #3, 430 ohms on #5, and 438 ohms on #7.
Hilariously, the gaps on the plugs are gargantuan, like "you could fly an airliner under the electrode and not reach its maximum operating altitude" gaps. #3 is 0.060" +; my next highest gauge is 0.080" and it's somewhat smaller than that. #7 is the same. #5 is also slightly in excess of 0.060".
Any of this seem normal to you guys? Seems crazy to me. I may just replace these "Silverstone" things with AC Delco platinums or iridiums. The wires don't look bad, but maybe the resistance is high?
ETA: 420 ohms is low resistance for spark plug wires, perhaps too low, and why I'm getting some crackle on the AM radio.
Hilariously, the gaps on the plugs are gargantuan, like "you could fly an airliner under the electrode and not reach its maximum operating altitude" gaps. #3 is 0.060" +; my next highest gauge is 0.080" and it's somewhat smaller than that. #7 is the same. #5 is also slightly in excess of 0.060".
Any of this seem normal to you guys? Seems crazy to me. I may just replace these "Silverstone" things with AC Delco platinums or iridiums. The wires don't look bad, but maybe the resistance is high?
ETA: 420 ohms is low resistance for spark plug wires, perhaps too low, and why I'm getting some crackle on the AM radio.
Last edited by FOGeologist; Aug 5, 2018 at 01:11 PM. Reason: Correction
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I've pulled off #3, #5, and #7 (boy, THAT one was no picnic) and discovered I have something called "Nowlogy Hot Wires." My plugs are "Siverstone Berus," whatever in the hell that is. Wire resistance is 422 ohms on #3, 430 ohms on #5, and 438 ohms on #7.
Hilariously, the gaps on the plugs are gargantuan, like "you could fly an airliner under the electrode and not reach its maximum operating altitude" gaps. #3 is 0.060" +; my next highest gauge is 0.080" and it's somewhat smaller than that. #7 is the same. #5 is also slightly in excess of 0.060".
Any of this seem normal to you guys? Seems crazy to me. I may just replace these "Silverstone" things with AC Delco platinums or iridiums. The wires don't look bad, but maybe the resistance is high?
ETA: 420 ohms is low resistance for spark plug wires, perhaps too low, and why I'm getting some crackle on the AM radio.
Hilariously, the gaps on the plugs are gargantuan, like "you could fly an airliner under the electrode and not reach its maximum operating altitude" gaps. #3 is 0.060" +; my next highest gauge is 0.080" and it's somewhat smaller than that. #7 is the same. #5 is also slightly in excess of 0.060".
Any of this seem normal to you guys? Seems crazy to me. I may just replace these "Silverstone" things with AC Delco platinums or iridiums. The wires don't look bad, but maybe the resistance is high?
ETA: 420 ohms is low resistance for spark plug wires, perhaps too low, and why I'm getting some crackle on the AM radio.
All looks good to me except the plug gap. Should be around 0.035" That could maybe be part of the AM radio static issue. Remember,, the OEM Plug wire resistance spec is 300 ohms to 700 ohms. SO, the resistance of the wire you have are spec good.
Regap them to the correct gap and see what happens.
BC
Last edited by Bill Curlee; Aug 6, 2018 at 12:41 AM.
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
I have decided that I'm going with Denso Iridium TT plugs from Rock Auto, about $48 delivered. I can get the Delco Platinums for $33 delivered. Delco Iridiums are $42 delivered. I have had good experiences with Denso plugs, and certainly with Delcos,. The prices are all close enough not to make a difference,.
Tonight I'll pull off three or four plugs and wires to see how bad they are, measuring the wires for resistance. I DO get quite a bit of radio noise that I would not have expected. Maybe my wires are shot? I am owner number 5 of this car, the prior owner being 75~ years old and driving the car only 4,000 miles in 14 years. I drive it daily, and have put 6,000 miles on it since March, including an 1,800 mile road trip about 2 weeks ago - the car performed flawlessly and returned nearly 29 miles per gallon on the highway.
The plugs could be originals or could have been replaced. The wire set is red in color - no markings. Were the originals red?
Tonight I'll pull off three or four plugs and wires to see how bad they are, measuring the wires for resistance. I DO get quite a bit of radio noise that I would not have expected. Maybe my wires are shot? I am owner number 5 of this car, the prior owner being 75~ years old and driving the car only 4,000 miles in 14 years. I drive it daily, and have put 6,000 miles on it since March, including an 1,800 mile road trip about 2 weeks ago - the car performed flawlessly and returned nearly 29 miles per gallon on the highway.
The plugs could be originals or could have been replaced. The wire set is red in color - no markings. Were the originals red?
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
Final tally:
Replaced all plugs with the Delco 41-110 Iridiums ($20 delivered, factory originals sealed in NOS packaging).
Removed the wires from the passenger side of the motor; one was very loose on the plug, which was pretty corroded. Tried to pull off the boot to fix the wobbly contact and the boot tore, along with the wire - dry rot.
Tried to buy a single wire - too short (was for a C6). Bought some cheapo Omni wires for $45, and they fit perfectly. Car runs just fine.
Replaced all plugs with the Delco 41-110 Iridiums ($20 delivered, factory originals sealed in NOS packaging).
Removed the wires from the passenger side of the motor; one was very loose on the plug, which was pretty corroded. Tried to pull off the boot to fix the wobbly contact and the boot tore, along with the wire - dry rot.
Tried to buy a single wire - too short (was for a C6). Bought some cheapo Omni wires for $45, and they fit perfectly. Car runs just fine.
Melting Slicks
Joined: Jan 2009
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From: Miami FL
Melting Slicks
Joined: Jan 2009
Posts: 3,275
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From: Miami FL
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
This is right off Gene Culleys CULTRAG Performance Parts forum add. The price may have change but the part numbers are correct. 12495519 – GMPP red spark plug wire set – $66.94
||--Genuine GM C5 Tune-Up Items--||
12495519 – GMPP red spark plug wire set – $66.94
12621258 – GM AC Delco Iridium spark plugs – $6.97 each
10287788 – 97 & 98 fuel filter – $14.18
19239926 – 99 – 04 fuel filter/pressure regulator – $88.70
25042562 – 97 – 04 air filter – $14.13
||--Genuine GM C5 Tune-Up Items--||
12495519 – GMPP red spark plug wire set – $66.94
12621258 – GM AC Delco Iridium spark plugs – $6.97 each
10287788 – 97 & 98 fuel filter – $14.18
19239926 – 99 – 04 fuel filter/pressure regulator – $88.70
25042562 – 97 – 04 air filter – $14.13