Lotus76

I am looking for advice on new spark plugs.

The gentlemen on the C3 fourm seem to like original AC plugs but it doesent sound like they have tried any newer technology so I come to the C5 guys for you thoughts.

I currently run Bosh 4008 Double Platinum plugs and fire them through a DUI (Davis unified ignition) distributor in my slightly modified 1976 L48 (heads, intake, cam, carb) with original 35 year old short block.

Its time for new plugs, I have been happy with the double platinums but over time they do have some build up.

I am looking for advise about Iridium plugs.

Good? Bad? Better? what brands are best?

or should I stick to Platinums?

Thanks John

C5Longhorn

I can't offer much advice on the platinum vs. iridium debate but can recommend a general plug choice that I have used and that is NGK. I've been very happy and just put copper NGK's in my '02 Z06.

Rick

vettenuts

Copper NGK's here as well. TR55 if you are stock.

C5FORFUN2

My '01 original Iridiums went 100K and still looked great, but I changed them anyway per maint. schedule, with the same.

Atok

NGK platinum is all I used in my C4 and C5. I gave up on the stock AC plugs because the platinum puck on the ground electrode kept disappearing. Maybe they have a better design now.

Bill Curlee

YOUR NOT going to really gain anything going from one plug to another plug. The only benefit of a rare metal spark plug is "LONGEVITY" They last longer than other plugs and the automakers need that for the warranty. You need it to keep from changing plugs every 10,000 miles.

Anyone that significantly MODS their LS engine, runs a COPPER PLUG. They actually seem to perform better than the rare metal plugs BUT,,,,,,,,,,,, they DO NOT LAST AS LONG!

Run what you like. There really isn't any HP real benefit between plugs. There are a few plugs that have a silver type electrode (for the life of me I cant think of all the names.. Goggle them if you want) and it cost a FORTUNE per plug. Some people searer by them in specific high HP applications.

For 90% for the C5/C6 owners, you cant beat an iridium plug and it will last a LONG TIME! Don't lose any sleep over spark plug selection. It isn't worth it.

BC

rws.1

Sage advice from Bill Curlee.....

Bill Curlee

Thanks RWS..

While were on the topic of plugs, Spark-plug Wires need to be discussed. Another case of ZERO HP gain between wires... Believe it or not,, the GENERAL did a really good job with the LS Ignition system. The STOCK COIL, PLUGS and WIRES will support 600-700 HP without fail (as long as there in good condition).

The stock LS black GM wires you get on your car will last a long time but sometimes get damaged on the first removal if your not careful. A GM up-grade is the GM performance RED WIRES. They wont give you any additional power but there EXTREMELY well made, fit correctly, wont pop off and look cool! GM uses the correct hardware and quality wire.

You can get a set from Gene Culley for right around $60. Just go to www.gmpartshouse.com and order them..

Bill

Cybermind

I agree with general consensus. I went with iridium NGK's for longevity. I had such a hard time changing them out that I am glad I don't have to worry about them anytime soon.

LoneStarFRC

Another Iridium user here. Iridiums will generally give you longer life than Platinums, but both are good and both give longer life than standard plugs.

I've been using Autolite's "XP" series in my non-stock engine for the last 18,000+ miles and have no complaints. They are actually a Platinum/Iridium hybrid. I just barely touch the key and the engine starts right up. Several brands such as AC Delco, Autolite, Bosch and NGK are good quality and all offer Iridiums.

By using a D.U.I., it sounds like you take good care of your ignition system.

HTH