Are original plugs really good for 100K mi.?

[Mark Oliverio]

I noticed in the owners manual that plug replacement isn't necessary till 100K. Your experience?

 

[CKA_Racing]

I've had my platinum tip plugs lose the little puck at 20,000 miles and at 70,000 miles. Problem is you need to remove them to be able to tell whether the puck is gone. I was able to tell once without pulling them out but I'm very in tune on how my enigne is suppose to run.

Just pull one or two from each side. That will give you an idea if teh pucks are missing. If you have around 60,000 miles I'd replace them anyways.

 

[Tuna]

Like CKA, I've found that the pucks dissappear between 30k and 50k - even on an LT1. I've been replacing plugs around 50k unless there is some indication that it is needed sooner. Now that my LT1 has been tweaked, I'll be checking them every couple of years just to see how long the new ones last.

 

[Hib Halverson]

I noticed in the owners manual that plug replacement isn't necessary till 100K. Your experience?

Saying that was GM's wishful thinking is an understatement.

I have yet to see any GM high-performance engine have OE plugs that last 100,000 miles. Wose, yet, the early AC double-plats had defects which caused the bond between the platinum "puck" and the electrodes to fail. That is why, as posted earlier, plugs manufactured in the 92-95 period had problems with this. After 95, Delphi finally got to a point where it understood the bonding process and the AC double-plats are far more durable.

I'd say, if an engine in a Corvette that is driven as it was intended to be, goes 50,000 miles on a set of OE-type double-platinum plugs that'd be pretty good.

What do I use?

Denso Iridium Power. In a LT4, I'd use the IT20

 

[FX GS]

Hib, do you use the factory gap setting?
also, what do you think about the cut electrode trick?

 

[Tuna]

Re: Re: Are original plugs really good for 100K mi.?

Saying that was GM's wishful thinking is an understatement.
----
What do I use?

Denso Iridium Power. In a LT4, I'd use the IT20

Where do you get this Denso plugs?

 

[lew]

I've had my platinum tip plugs lose the little puck...

Do any of you think that little puck could harm the engine? Seems to me if it got trapped between the piston and the cylinder wall...

Lew

 

[CKA_Racing]

Re: Re: Are original plugs really good for 100K mi.?

Saying that was GM's wishful thinking is an understatement.

I have yet to see any GM high-performance engine have OE plugs that last 100,000 miles. Wose, yet, the early AC double-plats had defects which caused the bond between the platinum "puck" and the electrodes to fail. That is why, as posted earlier, plugs manufactured in the 92-95 period had problems with this. After 95, Delphi finally got to a point where it understood the bonding process and the AC double-plats are far more durable.

I'd say, if an engine in a Corvette that is driven as it was intended to be, goes 50,000 miles on a set of OE-type double-platinum plugs that'd be pretty good.

What do I use?

Denso Iridium Power. In a LT4, I'd use the IT20

96 year should also be included because my LT4 has the common issue of losing the pucks. They also designed the Opti unit to last over 100,000 miles, that does not happen either as we all know.

 

[froggy47]

Hi Hib,

My LT4 has 50K on it so I guess I'll do the plugs, what about the orig. wires at 50k. Opti was done @ 25k.

 

[Hib Halverson]

Hib, do you use the factory gap setting?
also, what do you think about the cut electrode trick?

I open-up the gap on my Densos BUT...I also have an engine with "hot coils" which insures I have enough spark at idle with big-gaps. I would use the factory plug gap in most cases. As for the "cut electrode trick", I think this is filing the ground electrode...an old drag racer's trick. If that's what you mean, it's unlikely there's any practical perfomance increase in a street driven engine and it may damage the plug when done to plugs with platinum- or iridium-tipped electrodes.

 

[CKA_Racing]

Hib, do you use the factory gap setting?
also, what do you think about the cut electrode trick?

Yes, it works. You might as well index the plugs also if you are going to do the cutback. You won't feel the few hp that is gained though.
Too much of a pain to really worry about it if you ask me. Been there done that back in the day.