Re: spark plugs for a street 360
[Re: None2Slow]
#2767018
04/22/20 08:58 AM
04/22/20 08:58 AM
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Joined: Jan 2003
Posts: 1,758
Windsor, ON, Canada
Diplomat360
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,758
Windsor, ON, Canada
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Great experience with the NGK BKR5E-11 or BKR6E-11 (difference being the heat range). This is a V-grove plug, I've attached the spec sheet for both the plugs as well as the NGK plug naming chart.
Oh, in my case, I went from the hotter to the colder plug as I moved from a 9.5:1 to 10.5:1 static CR on my 360 motor.
Last edited by Diplomat360; 04/22/20 09:56 AM.
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Re: spark plugs for a street 360
[Re: Cab_Burge]
#2767063
04/22/20 11:39 AM
04/22/20 11:39 AM
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Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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Champion RN9YC(also RC9YCwill work) or maybe, if you can find them ,one step hotter RN10YCand RC10YC or Autolite #3924 or 3925, those two Autolite plugs have the 5/8 inch hex on them but they will work fine in your motor. I can't remember the proper part # for the standard Autolite 3/4 inch reach resistor spark plugs with the standard 13/16 hex on them  That’s too cold for a 10:1 pump gas deal. A champion RC12YC would be the coldest for that and most likely it will need a RC14YC.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: spark plugs for a street 360
[Re: madscientist]
#2767067
04/22/20 11:44 AM
04/22/20 11:44 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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NGK has a good rep. I'd say stock heat range or maybe 1 colder & go from there
live every 24 hour block of time like it's your last day on earth
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Re: spark plugs for a street 360
[Re: mopar dave]
#2767133
04/22/20 02:54 PM
04/22/20 02:54 PM
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Joined: Jan 2003
Posts: 3,122
Auburn WA
Dave_J
master
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master
Joined: Jan 2003
Posts: 3,122
Auburn WA
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A 3rd recommendation for RC12YC or equivalent other brand.
Retired, US ARMY 1973-1994
ASE mechanic, Electrical 1994-1997
Retired GTE/VERIZON/FRONTIER 1997-2015
Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.
03 Suzuki Burgman 650(Burger King) Scooter
65 Formula S Cuda
78 Little Red Express Truck
98 Buick Regal (wifes car)
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Re: spark plugs for a street 360
[Re: qwkmopardan]
#2768155
04/25/20 03:19 PM
04/25/20 03:19 PM
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Joined: Dec 2005
Posts: 11,551
Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,551
Fulton County, PA
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Autolite 65 would be a stock heat range, stock configuration (13/16, extended tip, 3/4 reach) plug. Go to 64 or 63 to go colder. This crosses to a BPR5ES NGK. Those are the only brands I would consider. The 5/8 hex is an Autolite 3924 which goes to a BCP5ES if my memory is correct. Champion? 
Last edited by CMcAllister; 04/25/20 10:19 PM.
If the results don't match the theory, change the theory.
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Re: spark plugs for a street 360
[Re: None2Slow]
#2768255
04/25/20 08:22 PM
04/25/20 08:22 PM
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Joined: Aug 2003
Posts: 43,157
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,157
Bend,OR USA
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I should have ask first if this is a iron head motor or aluminum head motor? If iron colder like I recommended originally is way safer than to hot 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: spark plugs for a street 360
[Re: None2Slow]
#2768271
04/25/20 09:25 PM
04/25/20 09:25 PM
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Joined: Jan 2003
Posts: 3,122
Auburn WA
Dave_J
master
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master
Joined: Jan 2003
Posts: 3,122
Auburn WA
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Iron stock. RN12YC or equivalent.
Retired, US ARMY 1973-1994
ASE mechanic, Electrical 1994-1997
Retired GTE/VERIZON/FRONTIER 1997-2015
Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.
03 Suzuki Burgman 650(Burger King) Scooter
65 Formula S Cuda
78 Little Red Express Truck
98 Buick Regal (wifes car)
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Re: spark plugs for a street 360
[Re: Dave_J]
#2768318
04/26/20 03:05 AM
04/26/20 03:05 AM
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Joined: Aug 2003
Posts: 43,157
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,157
Bend,OR USA
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The 1968 to 1971 340 motors came with N9Y plugs originally  They are not available any more I've been told so the closest one to them is the RN9YC resistor plug and then the resistor 5/8 body RC9YC in the Champion line. I had a 8.5 to 1 compression 350 Chevy iron head motor in a 21 ft. inboard outboard ocean boat that would ping with the stock RJ12Y plugs in it and wouldn't ping with a R11Y plug in it He is at 10.+ to 1 compression ratio so I'm thinking a #10 or #9 champion should be just about right at his altitude
Last edited by Cab_Burge; 04/26/20 09:29 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: spark plugs for a street 360
[Re: Cab_Burge]
#2768348
04/26/20 09:29 AM
04/26/20 09:29 AM
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Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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The 1968 to 1971 340 motors came with N9Y plugs originally They are not available any more I've been told so the closest one to them is the RN9YC resistor plug and then the resistor 5/8 body RC9YC in the Champion line. I had a 8.5 to 1 compression 350 Chevy iron head motor in a 21 ft.inboard out board ocean boat that would ping with the stock RJ12Y plugs in it and wouldn't ping with a R11Y plug in it H e is at 10.+ to 1 compression ratio so I'm thinking a #10 or #9 champion should be just about right at his altitude Cab, if you look up what Champion calls out in a newer catalog you’ll see it says a 12 heat range for that stuff. I can’t remember what year that changed, but IIRC there was an industry wide change in pump fuel blending (I think it was before OBDII but I wouldn’t swear to that in court), probably because of a federal regulation (wouldn’t swear to that in court either but that’s kinda what I remember) that required a heat range change.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: spark plugs for a street 360
[Re: madscientist]
#2768354
04/26/20 09:44 AM
04/26/20 09:44 AM
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Joined: May 2005
Posts: 1,977
Apollo, PA.
B1MAXX
top fuel
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top fuel
Joined: May 2005
Posts: 1,977
Apollo, PA.
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The 1968 to 1971 340 motors came with N9Y plugs originally They are not available any more I've been told so the closest one to them is the RN9YC resistor plug and then the resistor 5/8 body RC9YC in the Champion line. I had a 8.5 to 1 compression 350 Chevy iron head motor in a 21 ft.inboard out board ocean boat that would ping with the stock RJ12Y plugs in it and wouldn't ping with a R11Y plug in it H e is at 10.+ to 1 compression ratio so I'm thinking a #10 or #9 champion should be just about right at his altitude Cab, if you look up what Champion calls out in a newer catalog you’ll see it says a 12 heat range for that stuff. I can’t remember what year that changed, but IIRC there was an industry wide change in pump fuel blending (I think it was before OBDII but I wouldn’t swear to that in court), probably because of a federal regulation (wouldn’t swear to that in court either but that’s kinda what I remember) that required a heat range change. I think they have upped the heat range on the older engine listings because they assume they are old and need it to keep them clean from deposits of a high mileage engine.
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Re: spark plugs for a street 360
[Re: B1MAXX]
#2768454
04/26/20 04:33 PM
04/26/20 04:33 PM
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Joined: Dec 2005
Posts: 11,551
Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,551
Fulton County, PA
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We ran 55 Autolites in our iron head race deal for years. It used to be you just had to have cold plugs. But every time I stepped it up, the thing sounded happier. So that's what it got. Went to 3924s. Same basic construction & heat with a 5/8" hex.
If the results don't match the theory, change the theory.
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