Spark plug question Iridium? Platinum?
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Pro
Joined: Mar 2004
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From: Okemos MI
Spark plug question Iridium? Platinum?
I am looking for advice on new spark plugs.
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
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
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From: San Diego - Deep Within The State of CONFUSION!
If you're driving a modern fuel injected vehicle that is designed to go many tens of thousands of miles between services, then these types of plugs make sense. Our c3 engines certainly do not fall into this category
Race Director
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From: San Diego - Deep Within The State of CONFUSION!
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Melting Slicks
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From: Japan
I have seen direct side-to-side dyno comparisons from an engine builder that I know (as opposed to a magazine article where the plug manufacturer had purchased advertising) proving that there is virtually no measurable difference between cheapo run-of-the-mill AC or Autolite plugs and the super hi-dooda-dooda plugs used by NASA on the Space Shuttle. Of course these comparisons were done on low-tech pushrod carbureted engines, but honestly the best thing you can do for an old, low-tech carbureted car's ignition system is install an MSD box, add a good set of wires, and then index the cheapo plugs. Spending all that $$$ for superheterodyne unobtanium filament plugs is just a waste unless you're the guy at the parts counter selling them. If you don't want to contaminate your Vette's original underhood look, install a Pertronix. The AC plugs in my Pertronix-equipped C3 currently have 30,000 miles on them and the car's perfectly happy.
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
My heads use the flat gasket 14mm .750 deep reach plugs. Summit Racing did not have the autolite Iridium plugs in stock at the counter so I bought the double plantinum 3924
My ignition would eat common plugs for lunch. I pulled my common plugs once to look at the jetting and the center electrode was rounded and erroded away to where the gap was near .080. It still seemed to run fine.
I'd like to find a multi tipped or side ways jumping spark plugs
My ignition would eat common plugs for lunch. I pulled my common plugs once to look at the jetting and the center electrode was rounded and erroded away to where the gap was near .080. It still seemed to run fine.
I'd like to find a multi tipped or side ways jumping spark plugs
Last edited by gkull; May 4, 2011 at 09:19 AM.
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From: Florida
I have seen direct side-to-side dyno comparisons from an engine builder that I know (as opposed to a magazine article where the plug manufacturer had purchased advertising) proving that there is virtually no measurable difference between cheapo run-of-the-mill AC or Autolite plugs and the super hi-dooda-dooda plugs used by NASA on the Space Shuttle. Of course these comparisons were done on low-tech pushrod carbureted engines, but honestly the best thing you can do for an old, low-tech carbureted car's ignition system is install an MSD box, add a good set of wires, and then index the cheapo plugs. Spending all that $$$ for superheterodyne unobtanium filament plugs is just a waste unless you're the guy at the parts counter selling them. If you don't want to contaminate your Vette's original underhood look, install a Pertronix. The AC plugs in my Pertronix-equipped C3 currently have 30,000 miles on them and the car's perfectly happy.
My heads use the flat gasket 14mm .750 deep reach plugs. Summit Racing did not have the autolite Iridium plugs in stock at the counter so I bought the double plantinum 9324
My ignition would eat common plugs for lunch. I pulled my common plugs once to look at the jetting and the center electrode was rounded and erroded away to where the gap was near .080. It still seemed to run fine.
I'd like to find a multi tipped or side ways jumping spark plugs
My ignition would eat common plugs for lunch. I pulled my common plugs once to look at the jetting and the center electrode was rounded and erroded away to where the gap was near .080. It still seemed to run fine.
I'd like to find a multi tipped or side ways jumping spark plugs
The fancy metals just wear less, and wear leads to misfire, whether detected or not.
Back in the early 70's I tried NGK palladium in motorcycles, didn't seem to make much of a difference over oem. This stuff has been around forever.
Today, I use the cheapy Autolites in my modern FI engine but change them regularly. Iridium in my wife's hard to get to engine.
Denso makes the GM Irridium plugs, Autolite and Champion make most of the ACDelco plugs since Delco hasn't made their own in many years, Autolite makes the splitfires and so on.
Brand recognition is almost a thing of the past.
Anyone know what the AC in ACDelco stands for?
Melting Slicks
Joined: Feb 2003
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From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
St. Jude Donor '03-'05-'06-'07-'09
[QUOTE Anyone know what the AC in AC Delco stands for?[/QUOTE]
Albert Champion
Started AC after he was displaced from an earlier company he founded Champion Spark Plugs
Albert Champion
Started AC after he was displaced from an earlier company he founded Champion Spark Plugs
Team Owner
Joined: Aug 1999
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From: Ontario
Albert Champion
Started AC after he was displaced from an earlier company he founded Champion Spark Plugs[/QUOTE]
Interesting trivia! So Champion now makes Delco plugs!!
I get by with Delco R45TS very well with stock points, condensor, coil, etc. (1974 L-48).
Started AC after he was displaced from an earlier company he founded Champion Spark Plugs[/QUOTE]
Interesting trivia! So Champion now makes Delco plugs!!
I get by with Delco R45TS very well with stock points, condensor, coil, etc. (1974 L-48).
Thread Starter
Pro
Joined: Mar 2004
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From: Okemos MI
Thanks for everyone’s input.
I was not really looking for power gains. Although longer life would be a nice thing.
I was more concerned about keeping the plug clean and not fouled. I mentioned this was a original short block (never rebuilt) so I do get a little build up on the plugs over time.
I have seen demos (plug manufactures) that clams a stronger spark, less prone to foul or build up.
So I am asking the forum members for their advise about the platinum or Iridium plugs from that perspective.
Thanks John
I was not really looking for power gains. Although longer life would be a nice thing.
I was more concerned about keeping the plug clean and not fouled. I mentioned this was a original short block (never rebuilt) so I do get a little build up on the plugs over time.
I have seen demos (plug manufactures) that clams a stronger spark, less prone to foul or build up.
So I am asking the forum members for their advise about the platinum or Iridium plugs from that perspective.
Thanks John
I am looking for advice on new spark plugs.
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
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
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I always thought the fancy plugs were used in newer cars because they last longer. Some of these cars you have to use a trained monkey or take half the motor apart to be able to reach them to change them 
Drifting
Joined: Mar 2011
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From: PA
i was always told they are a big NO-NO on most carb cars....JMO
