L98 spark plugs
Thread Starter
Instructor
Joined: Dec 2014
Posts: 144
Likes: 9
L98 spark plugs
I am in process of fixing issues with service from local Chevy dealer. The guy I bought car from spent over $2000 at dealer in 2011 (3000 miles ago). Plug wires were ran wrong, burned one, one was not connected and another was broken among some of the issues. 3 of 5 plugs I checked are loose. I was looking at the AC Rapid Fire or the AC '100,000 mile' platinums. The right bank looks like a bitch so I want to do this right. Any ideas or preferences on spark plugs?????? 1991 L98 77,000 miles.
Thanks
Doug
Thanks
Doug
Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
Ac's worked great in my 86, completely problem free. I tried a few different plugs and had problems with it pre-detonating on me at cruising speeds when throttle was closed or almost closed.
Torque master plugs ran the best but they would detonated like mad at cruising speeds.
Torque master plugs ran the best but they would detonated like mad at cruising speeds.
Team Owner
Joined: Jul 2004
Posts: 28,432
Likes: 3,285
From: Hartford WI
I'm a little leery of the loose plugs. I would like to know if the threads are still good or whether they are FUBAR. If they are FUBAR, you might be better off taking them off and doing a helicore on them. I believe my cousin told me he had a plug work itself loose and popped out of the head. Don't know why it happened but it might not have been set in right. The least I would do is chase the threads with plenty of grease. If that isn't right, you might have to take it out an helicore it.
Safety Car
Joined: Nov 2008
Posts: 4,328
Likes: 15
From: Jacksonville FL
A/C D platinum #1 worked fine in my car. There was an article in I think "Super Chevy" magazine that did a plug dyno comparison and the #1s I thought had the best bang for the buck. SOP power seemed to increase but you know how that is. My car was having running issues (not plug related) and I pulled and cleaned them several times without problems.
I did go back to the regular stock R43S recently and they work fine as well. The car was designed for that plug and there really isnt any need to spend a bunch of money buying something that gains you a tenth unless you are tracking the car.
I did go back to the regular stock R43S recently and they work fine as well. The car was designed for that plug and there really isnt any need to spend a bunch of money buying something that gains you a tenth unless you are tracking the car.
Burning Brakes
Joined: Dec 2014
Posts: 1,038
Likes: 44
From: Pensacola Florida
I went with the 100,000 mile A/Cs on my 89, don't want to change them out anytime soon.
You are correct, the starboard side plugs are a nightmare, especially cylinder #1, under the A/C compressor.
If you have aluminum heads the threads are very long and it takes a lot of "worrying" to get them all the way out and back in. The port side is a piece of cake.
I slipped a piece of vacuum hose over the end of the plug so I could guide and turn it at the same time. It's a good idea to do one at the time so you have an angle reference when trying to rethread the tight ones back in.
Starboard side took about 6 hours, port side less than one. If you remove the compressor it would help a lot.
Rick
You are correct, the starboard side plugs are a nightmare, especially cylinder #1, under the A/C compressor.
If you have aluminum heads the threads are very long and it takes a lot of "worrying" to get them all the way out and back in. The port side is a piece of cake.
I slipped a piece of vacuum hose over the end of the plug so I could guide and turn it at the same time. It's a good idea to do one at the time so you have an angle reference when trying to rethread the tight ones back in.
Starboard side took about 6 hours, port side less than one. If you remove the compressor it would help a lot.
Rick
Melting Slicks
Joined: Jan 2008
Posts: 2,054
Likes: 120
From: AZ
Dang, Woody. It seems a certain Chevy dealer needs to get out of the fixing business.
Having read time and again to NEVER grease the plug threads, I don't, but would consider some anti-seize. However, I have never found the need for it.
Having read time and again to NEVER grease the plug threads, I don't, but would consider some anti-seize. However, I have never found the need for it.
Last edited by whalepirot; Jan 6, 2015 at 11:55 AM.
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Thread Starter
Instructor
Joined: Dec 2014
Posts: 144
Likes: 9
I went with the 100,000 mile A/Cs on my 89, don't want to change them out anytime soon.
You are correct, the starboard side plugs are a nightmare, especially cylinder #1, under the A/C compressor.
If you have aluminum heads the threads are very long and it takes a lot of "worrying" to get them all the way out and back in. The port side is a piece of cake.
I slipped a piece of vacuum hose over the end of the plug so I could guide and turn it at the same time. It's a good idea to do one at the time so you have an angle reference when trying to rethread the tight ones back in.
Starboard side took about 6 hours, port side less than one. If you remove the compressor it would help a lot.
Rick
You are correct, the starboard side plugs are a nightmare, especially cylinder #1, under the A/C compressor.
If you have aluminum heads the threads are very long and it takes a lot of "worrying" to get them all the way out and back in. The port side is a piece of cake.
I slipped a piece of vacuum hose over the end of the plug so I could guide and turn it at the same time. It's a good idea to do one at the time so you have an angle reference when trying to rethread the tight ones back in.
Starboard side took about 6 hours, port side less than one. If you remove the compressor it would help a lot.
Rick
Burning Brakes
Joined: Nov 2014
Posts: 936
Likes: 51
From: Post Falls ID
Champion makes a graphite-based thread lube for aluminum heads that works well. Used it on air-cooled aircraft engines for years. I also use it for other threads as a light thread anti-seize compound (comes in a small plastic bottle with a brush in the cap).
Most anti-sieze you buy now is a silvery paste, which is readily available in tubes or tubs. I agree with never using grease. In any head, iron or aluminum, it cooks out and you'll have a helluva time getting plugs out next time.
I also recommend Magnecor spark plug wires if you have to replace your set. They'll last a lifetime, and an 8mm custom-made set is around $130 shipped to your door. http://www.magnecor.com/magnecor1/main.htm
Most anti-sieze you buy now is a silvery paste, which is readily available in tubes or tubs. I agree with never using grease. In any head, iron or aluminum, it cooks out and you'll have a helluva time getting plugs out next time.
I also recommend Magnecor spark plug wires if you have to replace your set. They'll last a lifetime, and an 8mm custom-made set is around $130 shipped to your door. http://www.magnecor.com/magnecor1/main.htm
Last edited by 86C4Z51; Jan 13, 2015 at 12:40 PM.
Team Owner
Joined: Sep 2001
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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Anti-seize and Rapidfires for me. I change roughly every 2 years. I would never spend the cash on a 100k mile plug in an old engine.
Team Owner
Joined: Jul 2004
Posts: 28,432
Likes: 3,285
From: Hartford WI
For my diesels, I clean the chamber and remove the plugs every year to be safe. On gas cars, 2 years at most. Usually every spring I dump cap, rotor and plugs. Also mist spray the plug wires every winter.
Team Owner
Joined: Sep 2001
Posts: 62,146
Likes: 1,730
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Even if you gave them to me free, I'd still change them or at least pull them out of the head. I am deathly afraid of plugs, be they glow plugs or spark plugs sticking in the head. Had that happen on a diesel motor several times where the thin glow plug broke off. Had that happen on a L98 where the stock plugs were probably from the factory. Had a hell of a time with the PB Blaster and flame wrench before it came loose.
Team Owner
Joined: Jul 2004
Posts: 28,432
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From: Hartford WI
I've seen seized plugs and they aren't pretty
Team Owner
Joined: Jul 2004
Posts: 28,432
Likes: 3,285
From: Hartford WI
Not having to remove the head if a plug gets stuck. Besides, I do all my service at the start of the season and in the winter, I Idle the car every 2 weeks to keep the battery charged. Spring means fresh fluids, plugs, cap and rotor. Cap usually lasts about halfway into the next season and I don't want to fix in the middle.
Instructor
Joined: Jan 2015
Posts: 207
Likes: 1
Not having to remove the head if a plug gets stuck. Besides, I do all my service at the start of the season and in the winter, I Idle the car every 2 weeks to keep the battery charged. Spring means fresh fluids, plugs, cap and rotor. Cap usually lasts about halfway into the next season and I don't want to fix in the middle.
Racer
Joined: Nov 2008
Posts: 321
Likes: 2
From: Auburndale FL
