Frby98

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!

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!

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

Ragtop_Rob

Bill Curlee said " Over time these either wear away OR burn off!"

After 5500 miles 2 of mine were gone. The stock plugs leave some to be desired.

xlr8shn

Which non platinum plugs would you rec for replacment? NGK TR55?

Richin Chicago

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.

leaftye

You may be entirely right, but platinum still doesn't conduct as well as copper or iridium. Sure they can last for 100K miles, but it's not going to stay clean for 100K miles, so they still have to come out. I don't care what these plugs cost, but if they come out, with all the pain, cussing, bruising, and bleeding that comes with it, I don't mess around with reinstalling used plugs, I put in new plugs. That's just me, but I'm worth the cost of new plugs.

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.

MAC5

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".

leaftye

I have pics. I'll post them in a couple minutes.

leaftye

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.

MAC5

leaftye,

thanks, thats what I needed to see. All the ones I pulled today were missing that small puck.

IM QUIKR

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).

Richin Chicago

The part number on these plugs is TR55IX and I have put them in several C5's. IMO they are very good plugs. You can see more at:

http://www.sparkplugs.com

This is the construction Corvette is now using for all new cars.

EaglesNest

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.

panrixx

I know this a very old post but I've just removed my plugs and would be interesred in seeing the photo yoy had, as it's not appearing any more.

My plugs have the pucks in place but do have hugh gaps.

Thanks

Bob Chapman

I've used Bosch platinum 4 electrode puckless plugs for year on my Mustangs and Vettes and never had a lick of trouble with them. Going puckless works for me.

Chicago1

Holly Thread revival Batman!!!

HowlinC5

Wow 6 year old thread. Make a new thread.

mrm1149

The current Delco Irridiums have corrected the puck problem............