spark plug pucks?
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Joined: Aug 2004
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From: Greer SC
spark plug pucks?
I drove someone else's '00 Corvette over the holidays, and I noticed that he had a lot less "shimmy" at idle (general car shaking) than mine. I asked him about it and he talked about the spark plugs, and how they can lose their "pucks". No clue what that is!
What are the pucks?
Granted, his car has 10K miles, and mine has 40K, but could this be true? I thought the spark plugs were good for 100K miles. If I replace them, what brand do you recommend? And, is it difficult?
Lots of questions - thanks in advance!
What are the pucks?
Granted, his car has 10K miles, and mine has 40K, but could this be true? I thought the spark plugs were good for 100K miles. If I replace them, what brand do you recommend? And, is it difficult?
Lots of questions - thanks in advance!
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The spark plug electrode and cathode are made with a platimum, Irridium or pladidum material. If the entire spark plug cathode and electrode were made of these rare materials they would be "VERY" expensive and your wife would want to wear them! 
So,,,,, on the cathodes and electrodes they weld on a very tiny puck of platinum on the area where the spark jumps to and the cathodes are usualy capped with a simular type puck. Over time these either wear away OR burn off!
When they do you are left with a "REGULAR" spark plug with a "WIDER GAP" I changed mine out with Irridum plugs and it seemed to help the idle smoothness. NOTE Unless you are running a standard spark plug and up grade to a (rare metal plug) changing plugs will NOT usually provide a HP increase. Even if they do it will only be very slight. Going from one platinum plug to another (unless they are worn out) should not be that noticable.
Some boosted engines can not run certain rare metal plugs. I know that Buick Grand National TURBO V6 engine will not run properly with platinum plugs.
Thats my 2 cents on plugs.
BC
So,,,,, on the cathodes and electrodes they weld on a very tiny puck of platinum on the area where the spark jumps to and the cathodes are usualy capped with a simular type puck. Over time these either wear away OR burn off!
When they do you are left with a "REGULAR" spark plug with a "WIDER GAP" I changed mine out with Irridum plugs and it seemed to help the idle smoothness. NOTE Unless you are running a standard spark plug and up grade to a (rare metal plug) changing plugs will NOT usually provide a HP increase. Even if they do it will only be very slight. Going from one platinum plug to another (unless they are worn out) should not be that noticable.
Some boosted engines can not run certain rare metal plugs. I know that Buick Grand National TURBO V6 engine will not run properly with platinum plugs.
Thats my 2 cents on plugs.
BC
Safety Car
Joined: Sep 2001
Posts: 4,411
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From: Wilmington NC
Originally Posted by Bill Curlee
The spark plug electrode and cathode are made with a platimum, Irridium or pladidum material. If the entire spark plug cathode and electrode were made of these rare materials they would be "VERY" expensive and your wife would want to wear them!
So,,,,, on the cathodes and electrodes they weld on a very tiny puck of platinum on the area where the spark jumps to and the cathodes are usualy capped with a simular type puck. Over time these either wear away OR burn off!
BC
So,,,,, on the cathodes and electrodes they weld on a very tiny puck of platinum on the area where the spark jumps to and the cathodes are usualy capped with a simular type puck. Over time these either wear away OR burn off!
BC
Bill,
I believe the pucks on the Delco plugs weren't wearing off or burning off, because the plugs that still had the pucks look just fine compared to plugs on the same car that were missing pucks. I think what was happening is Delco was not using a good process in joining the dissimilar metals and a lot of the pucks were just falling off after exposure to combustion. I've seen 4 very healthy looking pulls and 4 plugs without any trace of pucks coming out of the same car.
As far as some cars not liking platinum I don't think that would be true any more with todays arc welder ignitions. If an older ignition system was marginal the extra resistance of platinum could have been the straw that broke the camel's back.
Safety Car
Joined: Nov 2003
Posts: 4,979
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From: San Diego, CA "leaf" "tee" "e"
Originally Posted by Richin Chicago
As far as some cars not liking platinum I don't think that would be true any more with todays arc welder ignitions.
The truck coil packs are even better than our coil packs, and MSD is coming out with even stronger coil packs....if our coil packs are arc welders, what are the new MSD's going to be? Can't wait to find out!
As far as other kinds of plugs, copper is great enough if you'll be replacing them every ~30K miles. They're CHEAPER too! Iridium's better IMHO. DJWorm has been pushing Beru plugs pretty hard, and his advice carries lots of weight with me, so I'll be checking them out when I replace my plugs again.
Drifting
Joined: Feb 2003
Posts: 1,761
Likes: 235
From: North Carolina
Does anyone have a picture of these old plugs with the pucks intact and a picture missing the pucks? I'm curious since I just replaced my 98's original plugs this afternoon. They were ACDelco 41-931's and I replaced them with the Delco Iridium 41-985's. The gap on those original plugs was huge. I'm curious to know if these 41-931's are the plugs that had pucks, because I can't see anything on these old ones that look like a "puck".
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Safety Car
Joined: Nov 2003
Posts: 4,979
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From: San Diego, CA "leaf" "tee" "e"
Here are some pics of my AC-Delco 41-931's from my '98:
Bottom plugs looks like the rest, and that thing on the tip looks like a puck. Top plug is one of the few without the puck looking thing.
Bottom plugs looks like the rest, and that thing on the tip looks like a puck. Top plug is one of the few without the puck looking thing.
Melting Slicks
Joined: Jan 2003
Posts: 3,251
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I have some used NGK TR55 irridiums I'd like to sell. These cost $6-7 each and since I now have a SC'r I don't need them(NGK TR6). They were used for less than 5000 miles and look new. They really smooth out the idle and throttle response. $15 + shipping(probably $8 UPS).
Safety Car
Joined: Sep 2001
Posts: 4,411
Likes: 1
From: Wilmington NC
Originally Posted by drcoffee
I have some used NGK TR55 irridiums I'd like to sell. These cost $6-7 each and since I now have a SC'r I don't need them(NGK TR6). They were used for less than 5000 miles and look new. They really smooth out the idle and throttle response. $15 + shipping(probably $8 UPS).
http://www.sparkplugs.com
This is the construction Corvette is now using for all new cars.
Instructor
Joined: Feb 2004
Posts: 190
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From: Murfreesboro TN
I put in a set of iridium plugs in my 99 and did not notice much difference. Then I put on a set of Taylor Thundervolt plug wires and that made a big difference in idle, and performance. I can't beleive that the original wires were that bad with only 44,000, but like the plugs they buy cheap and get cheap. Just my $.02. 
Heel & Toe
Joined: Sep 2004
Posts: 23
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From: Callington Cornwall, UK
My plugs have the pucks in place but do have hugh gaps.
Thanks
Race Director
Joined: Mar 2008
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From: Rio Rancho NM
