Simple plugs and wires question, please advise!
Thread Starter
Instructor
Joined: Mar 2008
Posts: 188
Likes: 1
From: Brookhaven Mississippi
Simple plugs and wires question, please advise!
Simple question I feel shameful for even asking......I have an 85 with 28,500 miles on it, still has original plugs and wires. It starts up fine, runs great and only has slight hesistation at times, idles well. I've pulled two of the plugs and they look good. If you observe the wires while running the engine in the dark you don't see a star wars battle sparking here and there, and the wires don't have any cracks, etc. But, we are talking about 23 year old hardware that's been exposed to 200+ degree temperatures Anyone else running original plugs/wires on a car that old? Or should I go ahead and replace them? 
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
BTW, another reason to change the plugs is originally it looks like your year came with platinum plugs (possibly ACDelco 41-817).
If that model plug also had a platinum 'puck' (spot of metal on the inside of the ground electrode), they are known to fall off, causing the gap to change drastically and adversly affect the car's idle and performance.
Since ACDelco does not make a compatible Iridium plug (per their website), your choices of iridium plugs (the prefered replacement to platinum) is limited -- suggest looking at NGK's -- per their web-site: UR5ix with gap carefully re-adjusted to OE spec of 0.45 inches).
If that model plug also had a platinum 'puck' (spot of metal on the inside of the ground electrode), they are known to fall off, causing the gap to change drastically and adversly affect the car's idle and performance.
Since ACDelco does not make a compatible Iridium plug (per their website), your choices of iridium plugs (the prefered replacement to platinum) is limited -- suggest looking at NGK's -- per their web-site: UR5ix with gap carefully re-adjusted to OE spec of 0.45 inches).
Thread Starter
Instructor
Joined: Mar 2008
Posts: 188
Likes: 1
From: Brookhaven Mississippi
BTW, another reason to change the plugs is originally it looks like your year came with platinum plugs (possibly ACDelco 41-817).
If that model plug also had a platinum 'puck' (spot of metal on the inside of the ground electrode), they are known to fall off, causing the gap to change drastically and adversly affect the car's idle and performance.
Since ACDelco does not make a compatible Iridium plug (per their website), your choices of iridium plugs (the prefered replacement to platinum) is limited -- suggest looking at NGK's -- per their web-site: UR5ix with gap carefully re-adjusted to OE spec of 0.45 inches).
If that model plug also had a platinum 'puck' (spot of metal on the inside of the ground electrode), they are known to fall off, causing the gap to change drastically and adversly affect the car's idle and performance.
Since ACDelco does not make a compatible Iridium plug (per their website), your choices of iridium plugs (the prefered replacement to platinum) is limited -- suggest looking at NGK's -- per their web-site: UR5ix with gap carefully re-adjusted to OE spec of 0.45 inches).
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Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 14
From: backwoods upstate ny
simple answer -- change 'em
fixed a bad skip in a 95 blazer 4.3 v-6, 20k miles, a couple months ago that had one plug wire shorting under load...lotsa room under that hood, fan was mechanical full time run IIRC, probly runs cooler underhood temps than a vette...highly recommend that you also change the "ninth plug" (the o2 sensor), best removed while the exhaust system is hot from engine run.
"spiral wound" conductor plug wires are far superior to "carbon suppression core"
"spiral wound" conductor plug wires are far superior to "carbon suppression core"
Team Owner
Joined: Oct 2000
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From: Fort Knox, KY
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I like the NGK TR-55 Double Platinums. It's what I'm firing in my '92 now. And I would change those wires, too.
If you have aluminum heads (they didn't get phased-in on the L-98s until 1986, right?) don't forget the anti-seize compound on those replacement plugs, too.
If you have aluminum heads (they didn't get phased-in on the L-98s until 1986, right?) don't forget the anti-seize compound on those replacement plugs, too.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 763
- i'd also pull the throttle body and give it good cleaning. that should clean up the slight hesitation. i just bought a 90 w/42K miles - same issues. i'll be changing the plugs, wires, cap and rotor, and cleaning the throttle body shortly. this should give me (and you (OP)) a good performance baseline. 
Le Mans Master
Joined: Feb 2003
Posts: 9,087
Likes: 0
From: Chicago IL
- i'd also pull the throttle body and give it good cleaning. that should clean up the slight hesitation. i just bought a 90 w/42K miles - same issues. i'll be changing the plugs, wires, cap and rotor, and cleaning the throttle body shortly. this should give me (and you (OP)) a good performance baseline. 
Le Mans Master
Joined: Feb 2003
Posts: 9,087
Likes: 0
From: Chicago IL
Thread Starter
Instructor
Joined: Mar 2008
Posts: 188
Likes: 1
From: Brookhaven Mississippi
I used electronic parts cleaner from Radio Shack, it rapidly dissolves and did a great job. I comes in an aerosol spray, about $10, it's the same stuff I used to clean the volume control on an old Denon integrated amplifier. I removed the MAF unit and sprayed several short bursts on the intake side, then did the same on the other side, let it sit out about ten minutes to dry then reinstalled it. I took a fine cotton rag and wiped over the screen too. After hooking it up and cranking the car it took a few seconds for the car to smooth out, it ran much better and response was improved too.
Last edited by birddog85; Sep 18, 2008 at 06:07 PM.
Drifting
Joined: May 2008
Posts: 1,692
Likes: 490
From: Denver, NC
He's worried about an intermittant driveability concern. The screen is designed to make the air passing through the MAF flow over the wire and give an accurate reading. Don't you think it would be best for him to fix his concern prior to introducing change to a critical sensor?