Spark Plugs for LA w/magnum heads

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straightlinespeed

straightlinespeed

Sometimes I pretend to be normal
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Hi guys, I was just doing some research on plugs and starting to think I have the wrong plug in my engine. I have a LA360 with magnum heads and running Champion RC12LC4 which are the correct plug for magnum heads, but cant find any heat range info. I based this off of a 98 Ram with a 5.9. If I understand correctly I have to run that style plug because its a bit longer to get into the combustion chamber.

Since I could not find any heat ranges with Champion Plugs I went NGK's website and got info for a 98 Ram and a 74 Dart. Using NGK's website I put those numbers into Summit racings site and compared plugs. Looks like the Ram has a heat range of 6 and the Dart has a heat range of 4. I dont know how much this affects the car but I want to make sure I have the correct or best plug in my car.

So now Im wondering what plug I should be running in my car, or what are you guys running for plugs that you found work best for a LA engine with Magnum heads??
 
FR4 in NGK is a .750" reach, 5/8" hex resistor spark plug for mild compression/driver setup, 4 being a hotter plug.
R5671A-7 is the race style plug that is the same .750" reach gasket plug with 5/8" hex but a 7 heat range, being a colder plug for higher CR.

General info above, heat range would depend on your actual combo and use.
 
Now that I know Im running the correct plug. How do you guys feel about Champion plugs? Do you think there is a better performing plug?
 
I don't want to flame your thread here; a good high energy ignition system will go a long way in making sure all your fuel is burnt well here. HEI swap comes to mind stock plug should do well in your application.

:hello2:
 
PoisonDart74 said:
I don't want to flame your thread here; a good high energy ignition system will go a long way in making sure all your fuel is burnt well here. HEI swap comes to mind stock plug should do well in your application.

:hello2:
Click to expand...

Dont worry about it, Im thinking my ignition system is lacking anyways. They had to back my engine off at 6k at the Dyno, because it was falling off. Due to the ignition system not keeping up. I've been debating about Trail Beasts HEI set up actually.
 
The HEI swap was a night and day difference in my beast back when it was running. Worth the $100.
 
Even a simple phasing and recurve can move a stock distributor in the right direction, with an aftermarket ECU feeding it. The stock electronic stuff jumps everywhere.
 
I wouldn't run champions in a lawn mower. NGK'S are a far superior plug.
 
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