ronw
Well-Known Member
I have a 540 cu. in. 10.5 to 1 compression. Trying to decide what make plug and heat range to use. thanks ron
What spark plug?
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540? Is that a typo?
ronw
Well-Known Member
No, It's a 440 Mopar Performance Siamese block stroked to 540 cu. in.
New build or has it been run? What plug is in it now?
ronw
Well-Known Member
Has not been fired yet still working on headers for the 68 Dart that it's in.
I would say start out with a standard 440 plug and go from there. You will have to read the plugs after a dyno run or cam break in. Use search here for reading spark plugs. With that much compression you may need a colder plug. There won''t be a one size/fits all plug for your application.
ronw
Well-Known Member
thanks
roccodart440
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For what it's worth this is why I like breaking them in on dynos. I wouldn't even think of spending that kind of money on an engine and doing a first fire in the car.
leblanc
member 2883
Phone a spark plug maker, tell him what you have and most of them should be able to help.
ronw
Well-Known Member
Thanks, not everyone has access to a dyno or the money as in my case!
I always break them in on a run stand because if there is any problem it's easier to fix when it's out of the car and when everything is right, oil changed, ran again with no problem then it goes to the dyno if I want to dyno it. But first run is always out of the car.
Marcohotrod
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What cylinder heads
roccodart440
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If you have the money to build an engine like that but not 500 dollars to spend on a dyno day to safely break it in and get it tuned right I'm truly lost.
roccodart440
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Out of the car makes sense. A dyno still has advantages for break in but doing it in a car, especially with a pricy build scares me.
yellow rose
Overnight Sensation
Do NOT use a stock 440 plug UNLESS you are using stock 440 heads. Those stock heads use a J series Champion and most aftermarket heads use the N/C series Champion and they ain't the same.
If it's a stock head, you can start with a J12YC and tune it up from there.
If it's aftermarket heads, you can start with a C12YC and tune it up from there.
I use the C series because the 5/8 hex gives more room than the 13/16 hex.
If it's a stock head, you can start with a J12YC and tune it up from there.
If it's aftermarket heads, you can start with a C12YC and tune it up from there.
I use the C series because the 5/8 hex gives more room than the 13/16 hex.
Great reply. As usual there is a lot of missing information. I was thinking about that earlier. If you are running aftermarket heads you should probably contact the manufacturer for their recommendation.
ronw
Well-Known Member
Thank you everyone, a little more info. The eng has Indy max wedge heads and intake
Good to know. Call Indy they know what plug you need. We are only guessing.
Marcohotrod
Well-Known Member
C10YC or C11YC champion or equivalent autolite, call indy
famous bob
mopar misfit
I`m guessing their aluminum ? -------I started w/ 3/4 reach ngk 7`s, down to ngk 6`s now.
alum. heads take longer plugs. 3/4 reach-----------
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