# Spark Plug question.



## 70monte (Feb 5, 2008)

I'm currently running AC-Delco Rapidfires in both of my 98 chevy trucks, one with the 5.7L and one with the 7.4L. Both are using the newer platinum tip Rapidfires. The 5.7L is due for a plug change soon and I was wondering what I should use. The current recommeded plug for both engines is the Delco 41-993 which used to be a platinum plug and is now an iridium plug. I was wondering if I should stay with the Rapidfires or go with the new iridiums.

I have never run iridiums in either of these trucks so I don't know if there is any difference in how they would run with these compared to the factory platinums. 

I went to the Rapidfires originally because the factory Delco 41-932 platinum plugs used the platinum hocky pucs on the side electrode and they tended to fall off over time and increase the gap. Thanks for any suggestions on this subject.

Wayne


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## MarkEagleUSA (Nov 27, 2005)

I've always been told that the 5.7 Vortec's really like the specified plugs. I run the 41-993's in mine and haven't had any problems. I think the iridium's are just designed to last longer than the platinum's but are functionally the same.


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## carkey351 (Oct 18, 2010)

in my opinion, unless the manufacturer recommends iridium's, I don't run them in car/truck engines.

I feel they are best used where there is more fouling (motorcycle, snowmobile, etc.) and the extra cost isn't worth it, especially when replacing 8 of them.

In all chevy gas trucks that I've had, I've run platinums and had great luck getting lots of miles out of them. I even had a 4 cylinder car that still had original platinums with over 120,000 on them, so them must be good.


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## theholycow (Nov 29, 2002)

I'm a fan of using exactly what is specified for spark plugs. However, on a short budget I've been known to go cheap and it worked out fine. My 2002 5.3 specifies AC Delco iridium but I've used cheapo Autolite copper before, and currently have Bosch platinum (which were under a buck a piece from Rockauto).


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## 70monte (Feb 5, 2008)

The only two Delco plugs recommended any more for both of the trucks is the 41-993 which is now an iridium plug and the Rapidfire plug which is a platinum plug. The Rapidfire plug was never originally specified for either application and neither was an iridium plug. I guess my main question is whether or not the iridium plugs are better than the platinum Rapidfires as far as performance goes. I want to stay with AC-Delco so those are my two choices, though I think that the Delco iridium plugs are actually made by NGK.

Does anyone know how long the Rapidfire plugs are supposed to be good for? I can't seem to find this info anywhere though I want to think that I read somewhere when they first came out in the platinum version that they were good for 50,000 miles. I have 47,000 miles on the ones in the 5.7L. Thanks for the information everyone.

Wayne


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## carkey351 (Oct 18, 2010)

70monte;1592732 said:


> Does anyone know how long the Rapidfire plugs are supposed to be good for? I can't seem to find this info anywhere though I want to think that I read somewhere when they first came out in the platinum version that they were good for 50,000 miles.


Yep; according to this 50,000 is it: http://www.summitracing.com/search/product-line/acdelco-rapidfire-performance-platinum-spark-plugs

Depends on the brand; some platinum's last 100,000, others less. I've even seen iridium's rated for 150,000. It really doesn't matter what you use, they are both good. I've had a couple parts guys tell me that cost wise the platinum's are the way to go, but they agreed it didn't matter performance (at least not that you would notice).


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## 70monte (Feb 5, 2008)

Thanks for the summitracing link. I found out that my info for the 7.4L was wrong. The recommended plug is a Delco 41-933 and a Rapidfire # 12 which are both platinum plugs. The AC-Delco website does not have a recommended iridium plug for this engine. The Rapidfire # for the 5.7L is #14 though the rockauto website says it can use both the #12 and #14. 

I will probably just go back with the Rapidfire in the 5.7L since I have not had any issues running this plug. Thanks again.

Wayne


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