Best plugs for street 340? Thanks for all the input!

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dragondan64

dragondan64

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I am getting ready to install my newly rebuilt mild 340 in my barracuda and have been looking at plugs. I am running mopar performance electronic ignition and wires with an MSD coil, the engine has a 280 484 PSC and running headers, edlebrock air gap intake with 600 carb, compression is 10-1 flat tops are the E3 plugs good or what are some recommendations? Thanks for any advice! Danny
 
Champion RN14YC. E3s are snake oil bullcrap.
 
Go with champions. The e3 plugs are just marketing hype. No noticable horsepower increase or enough milage increase to justify the extra cost.
 
I am curious also. I have run iridium plugs in my Dakota r/t and really enjoy the difference. They smoothed out the idle and start better, not to mention it revs quicker. Are these responses from experience or just assumptions. When I get home, I am planning alittle testing on this and I am also looking at different plugs for my BB Duster. I do know you have to be carefull with plug choice with the higher powered aftermarket ignitions.
 
No assumptions involved. I ran E3s in my 08 Jeep Wrangler. It got crappier mileage and threw misfire codes left and right. Also caused the engine to occasionally shake the entire Jeep like torque converter shudder. Put the Champions back in and it was perfect. It's not just with computer controlled stuff either. They plain SUCK.

The iridium stuff is different. That's not even in the same category as multiple electrode stuff. These old engines don't need all that fancy stuff. Be dumb with your money if you want too. The farthest I'd go if I wanted an "upgrade" would be to something in NGK, but there's no NEED for that. All a spark plug can do is spark. And that's the truth.
 
the E3's are good for target practice with your colt 45

just chuck it up in the air POW just like john wayne
 
I've run Autolite since 64 with no problems.I use 65's in my 440. I don't know the number for my small block and will change as I now use plugs for a magnum. The 5/8's heads makes tightening a pain. I raced with Maverick in the early 60's . The autolight guy help us find the right plug for the 13:1 max wedge and I 've used them ever since. Am I old? You bet I am!
 
Probably something equivalent to an NGK 6 or 7 and you'll be good.
 
RN14 plugs are way to hot for a 340 , they call for RN9Y and the later 340 used RN12Y A RN14 with and MSD is gonna be a perfect situation for detonation
 
Snake said:
Horse power show is it bull ****? they did some test on the E3 and there were some gains over regular plugs just saying.:???:
Click to expand...

E3 is one of their PAYING sponsors. If you wanna believe their bullcrap, that's on you, bud. Jes sayin.
 
My mistake on the plugs. The book calls for RN12YC. Run 9s if you want to but they will load up eventually.
 
NGK U-groove. Been running them since 85, no problem. dime more than autolite/champion.
 
in Champion RN12YC for pump gas and street driving, hot enough to stay clean but not pre-ignite decent gas
like posters above state, in stock high compression 340 you cant go wrong with Autolite 65 (or 64 for strip/track extended high RPM, minimal part throttle/idle)
 
The iridium a are a whole different thing. They do help. All the multiple electrode crap is just market ing hype don't really do much if anything. On the wife's car it messed with the ECU and threw codes so out they went. I tried the old Bosch multiple electrode stuff and it did nothing
 
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