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Triple dueces its great you mentioned Jacobs, when we did our test the Jacobs electronics worked the best of any period and with the higher voltage the plugs that were not as good fell to the way side and back in the late 80s and early 90s Accel was junk period! Thanks for the info on them CutlassEFI maybe now they will perform and last. We found for the money and performance Autolite's were the all round best plug back then. Things change and I like the NGKs, but its whatever works best in your motor.
To add to the above, one of the big reasons for manufacturers going to fine tipped (platinum, etc) plugs is to meet emissions requirements. When a plug misfires, the unburned fuel goes into the exhaust and increases tailpipe emissions. In order to prevent this, the plug has a very pointed tip that is guaranteed to fire almost every time.
Yeah that's pretty much what I said.
The downside to this is the spark will jump the gap at a very low voltage, which is not optimum for performance. Performance cars typically have a high-energy ignition system, but if the plug allows the spark to jump the gap at 5000 Volts, then what is the point of having that 50,000 Volt ignition system?
Simple, as cylinder pressure increases so does the voltage requirement needed to fire the plug. That's why performance engines use a higher voltage coil. Typically increased cylinder pressure equals increased performance.
Also inductive systems, i.e. LS engines, normally put out less overall power but fire the plug for a longer period of time, hopefully burning away deposits.
Simple, as cylinder pressure increases so does the voltage requirement needed to fire the plug.
Agreed. My point was that if someone is just changing plugs and not altering the CR or the ignition system, using pointy tipped plugs will allow the spark to jump the gap at a lower voltage.
Seriously? Concened about what spark plug to use for a street car probably with pump gas? I'd be more concerned about the relative humidity than a spark plug brand, unless I was going to mars in another type of 'rocket' engine
I have been running bosch platinum plugs for several years gapped at .060. I gave up on the .080 gap on the ac-delcos. I will be installing my new Nitrode performance SP-NP28 plugs this spring with my current taylor 8mm wires. Have you guys checked out these plugs.
I just purchased a 72 and I trying to learn as much as I can so I can work on my car by myself. That being said I don't have a background in autos.
What would be the best spark plug for me to use?
Year old thread but I still say NGK. Autolite and AC Delco are OK but are now Chinese made, I believe. Just get NGK XR45 or XR5, higher number equals colder plugs in the NGK world.
The new AC Delco and Autolite are pretty much the same. Not terrible, just not as good as before. They used to be the best on the market. NGK has made plugs for years, if anything they are better than a few years ago. God bless outsourcing to maximize profits for the share holders.
Ive been running Autolites in my engines since 1986 most with HEI. I get great longevity and great spark. I assume great spark when reading what the plugs look like after many miles. And they are cheap to boot. I cut the electrodes back a bit too in the 11:1 car.
NGKs go in the 3 wheeler honda and weedeaters. These types of engines like the NGKs as it was OEM. Zero luck with Champions in anything except a Chrysler leaning tower of power and 318s.
i have a 72 rocket 350. i just bought some for my car. you look at the conductivity of the metal. they have coppers/platnum/al mumin. i prefer copper my self but its all up to you and if you want proformance or fuel economy or both.
Not a stupid question especially today with the abundance of cheap offshore junk. What was once a good product is no longer. I no longer purchase A/C or Autolite.
It requires savvy shoppers to do their homework for things we used to take for granted...simple things like spark plugs, caps, rotors, points...food...
So these types of questions, while steadfast years ago, constantly need to be updated as the market degenerates/disintegrates/regresses....er I mean evolves.
Currently, NGK V-Power XR5 is good. Good quality and made here if you can believe it.
Lots of discussion about spark plugs without bringing up indexing the plugs...hmm?
I tried indexing. Got the special multiple thickness plug washers for that propose when I had the heads off. I could not get many of the plugs in the right position.
For me it was a waste of time and money.
Found a "set" of seven very old AC R44S (mildewy boxes, but you could still read 'made in USA' on them) on the shelf at a local mom 'n' pop parts store couple of years back and rounded off to eight with the help of Adam, a member here who had an old one kicking around.
I had issues with Bosch Platinums back in the 90's in two of my GM passenger cars. They started missing real bad after around 10 to 15 thousand miles. I changed back to AC/Delco plugs and no problems. Never have tried the Platinums again.
My '72 442 with 455 had Champion RJ-12Y plugs in the 455 when I bought it off my brother. My brother was the second owner and I believe the Champions were in the motor from the first owner when he drag raced it back in the 1970's & early 80's. When I got the car I replaced the Champions with AC/Delco that were listed for the motor and, to me, it didn't seem to run as well. Eventually and few years ago, I found one of the original Champion RJ-12Y plugs and bought a new NOS set off Ebay and installed it the 455 and it seems to run noticeably better just like it did when I bought it from my brother. I bought another full set off Ebay as a back up set. The Champions did seem to make a difference to me.
I looked up the Champions and they are listed as being for a W-30 (which my car is not). When I had the carb rebuilt years ago the person who rebuilt it asked me if it had a big cam in the motor and I said "no", and that it sounded smooth at idle like a passenger car. He said the butterfly's had holes drilled into them and that guys did that so a motor with a lumpy cam would idle. He also said that things with the carb were modified with extra springs so when you hit the throttle it snapped the carb open?? Seems weird that someone racing this would go to all that trouble on a stock low compression motor. But then, even though it's numbers matching, I really do not know what is inside the motor.
Any rate, my 455 likes Champions!
Last edited by OLE442; December 27th, 2021 at 05:53 AM.
Reason: added text
I actually had good luck Bosch Platinums, even ran them in an Olds 307 and Olds 350. A lot of people had issues with Champion, they worked fine in my old 77 Dodge Van. My Uncle was one of them, had misfire issues. My old Boss had his own shop, he also saw issues with Champion plugs. He used Autolite except for trucks that towed especially if they were having misfire or pinging issues. He used the now discontinued Champion Truck Plugs, really good plugs. Now everything is Platinum at minimum. Most new vehicles have Iridium from the factory.
April 23rd, 2013 | 12:52 PM
