Mylzi

My spark plugs have been driven about 50000km/30000miles and I am getting new ones now. Plugs are Ac Delco Platinium and box says that those should last 100 000 miles..

How often you change spark plugs to ZR1?

secondchance

How often varies with type of plugs in my opinion.
I have been using AC Delco Rapidfire, conventional plugs. I change these around 10,000 miles.
I had a bad experience with AC Delco platinum when I first tried a set about 5 years ago - cracked insulator resulting in hesitation that took a while to figure out.
Some swear by Denso Iridium.
Hopefully one on the gurus verify this but my understanding is depending on the cylinder 4 cylinders fire in reverse, flame migrating from ground to tip in which case platinum tip, if only on the positive electrode, become a mute point.
I suggest searching posts on ZR1.net. Older threads discussed finer points of various plugs.

VetBoyZR1

My car is almost 15 years old and the plugs are one thing I haven't even considered thinking about. I only have 14,000 miles on my car.

secondchance

Be careful. It may rust away from lack of use!
I put on 80,000 in 9 years - about 7th set of plugs.

VetBoyZR1

So, you think it's necessary to replace functional parts? You're obviously replacing things that don't need to be replaced. The suppliers on here love guys like you.

VetteMed

Listening for more on this....?

secondchance

No. I am just kidding you about low miles you are putting on.
In 80,000 miles, I do go through some parts. However, never more than necessary.

Mylzi

Car runs great with new AC Delco platinium plugs

Quite big ´tune up´.. New fuel injectors, DIS module and spark plugs.

Paul Workman

For street use, occational sprited driving, and maybe a few passes at the track, but well under 3500 miles a year, as a rule, "state of the art" platinum electroded or iridium coated platinum may out last me!

I have a couple of DDs I use in my construction work - both have over 140xxx miles on a set of standard plugs! There are no mis-fires, no starting problems, no missing under WOT...NO reason to change them then either, just because some manual says to.

However, a track car, especially one running on corrosive (special) fuels and fired by extremely high output, mulitple-discharge magnetos (e.g., MDS setups) is a different situation.

For street use tho, the standard Delco plugs are cheap enough and easy enough to replace that I don't see the need for spending upwards of $10 per plug for platinum - especially at intervals of less than 30,000 miles or as needed.

So, if it winds your clock to do it more often, go for it! But, I would steer away from (needless) platinum - so as to double (triple?) needless expense. A dedicated track car...is a different animal with different needs.

Just my opinion.

P.

Aurora40

It's called "waste spark". If you notice there are 4 coils but 8 cylinders. They are paired on opposite cylinders. When one cylinder is firing the spark plug for the power stroke, it is also firing another spark plug on its exhaust stroke.

I have heard it a lot with Northstar/Aurora guys that if you don't have dual-platinum plugs, it will erode the ground strap on the waste spark firing. I'm not familiar enough with other cars to know if they had similar problems.

The Buick V6 uses waste spark, but I've always used AC Delco dual-platinums on ours. I'm not sure any LT5 owners pile the miles on their plugs without changing them.

I also don't know if iridium plugs will have the same problem. Only the tip is iridium though, so perhaps it will wear the ground strap away too.

I've wondered if I can go 50-100,000 miles on the NGK Iridiums I have, but so far I've only put about 15-20k on them.

Secondchance, you may want to ditch the Rapidfires. I think they tend to be a hot plug. I had a lot of spark retard with them that greatly reduced when I swapped them out.

secondchance

What would you recommend without going to exotic stuff?

VetBoyZR1

Mylzi - you should win some kind of award for your dedication to the ZR-1. I know I've been in contact with you for 7 years or more, and you continue to get things done and stand by your Z, even though you have only so many resources available in Finland. You are a loyal ZR-1 owner!! And thank you again for the things you've sent me over the years!

Goldcylon

Just plain Delcos work fine.

Mylzi

Thank you

Problem is that car still doesnt work..

4cefed

Why go with anything else. There is no reason.

Duntov85

The plugs may last 30K, 50K, or 100K. But at 100k could you get them out of the head still installed on the vehicle??

Denso Iridium is the best sparkplug money can buy in my opinion.