Please I need advice/inputs,, NGK or CHAMPION

[Olle B]

Well I try to get my car to start nice and gently both cold and warm,, its not easy,, I can tell!!

One thing thats different from last year is a sparkplug swap.
Its for my 383 with 10 to 1 compression and Holley SD with 750 and 1" 4 hole spacer.

Does it matter if I use:

NGK BP6S

or:

Champion RJ12YC

The one thats in the car right now works when the engine is warm,, but they are terrible to fire up at cold,,

I have no idea if the plugs could play any diff,, thats why I ask you pro`s.

I wont tell you whats in the engine before YOU have answered,, I dont wanna point you into any direction,, I just need your spontan comment regarding the two plugs,, are they equal or not??

PLEASE!!

Best R Olle B

[horatio102]

searching NGK's website they don't recognize that part number.
The correct plug, guessing you've got a 6.3l 1970 RT is a NGK XR5.

A 6 heat range is one step colder.

The Champion RJ12YC is the correct plug for the application.

hm, looks like sparkplugs.com and not the actual manufacturers website, but either way, the NGK doesn't sound like it is the right plug for the job. I'm going to guess that you've got NGK's in it now.

[dwc43]

Your car should just use teh J12YC. The R means it has a resistor and in '70 they did not use these. The J is the plugs reach and 12 is the heat range, Y is an extended tip, and is a copper core. THe Champions are what you need. And msd box attached to a stock electronic dist will get that thing started every time. You should consider switching over to an msd box and dist. if you dont already run one. Then your plug gap can be increased to at least .045 with the msd box.

[MoparMarcIdaho]

thats what the factory put in there,heat range is everything.Put a set of nippondenso U electgrodes in a tired 318 once and woke it right up.Tried splitfires in my harley when it was tired and it liked them but when rebuilt it detonated bad,had to go back to oem type and heat range.So you be the judge.