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spark plugs ?

Posted By: sixbbl 69

spark plugs ? - 01/18/18 07:06 AM

69 440 six bbl with mopar performance alum heads.525 hp pump gas. what type and number plug should i start with for first start up.
Posted By: A/MP

Re: spark plugs ? - 01/18/18 07:07 AM

stock '69 440+6 plugs
Posted By: sixbbl 69

Re: spark plugs ? - 01/18/18 07:11 AM

J11Y won't fit the heads.
Posted By: madscientist

Re: spark plugs ? - 01/18/18 07:48 AM

RC9YC champion

Use a 12 if it's under 10:1
Posted By: Cab_Burge

Re: spark plugs ? - 01/18/18 08:20 PM

Do you know the compression ratio and octane rating you will use?
I have a 505 C.I. 440 block that has right at 10.08 to 1 compression and I'm going to use Champion RC12YC on our local pump swill. I've had other pump gas motors with a little more compression, 10.78 to 1, that I used champion RC9YC and Autolite AR3911 non resistor race plugs and AR3910 non resistor race plugin them with good results up
I went out to the shop and got couple of other Autolite resitor street pump gas plugs, 3924 and maybe 3925, which is hotter, if they make that plug number now scope
Good luck, let us know what you use and your results scope
Posted By: sixbbl 69

Re: spark plugs ? - 01/20/18 04:08 AM

thanks Mad and Cab
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