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BBC running rich - Spark plug-heat range-manufacturer Advise?


snomobeelr

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So I am running rich and looking to run a hotter spark plug . I currently run the NGK - R5671A-7 (Non-projected) . That plug is the hottest for that model of plug. NGK does make other plugs that are hotter but are as they say are "Projected ". And a little longer in the cylinder. I am told the lower the number on the NGK the hotter the plug is. I am going to just go 1 number down so was going to go to a 6. Anyone use something else or have any advise?   

 

 

 
R5671A-7 : Non-projected : Manufacturer Heat Range: 7 : NGK Racing  Spark  R5671A-7/4091  
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BKR-6-E  : Projected     : Manufacturer Heat Range: 6 : NGK V-Power Spark  BKR6E/6962 
bcpr6eg9 : Projected     : Manufacturer Heat Range: 6 : NGK G-Power Platinum Spark Plugs BCPR6EGP/7088
NGK FR5  : Projected     : Manufacturer Heat Range: 5 : NGK V-Power Spark  FR5/7373  
 

 

 

Engine Cubic Inches:    468
Compression Ratio:      10.1
Intake Manifold Brand:  Edlbrock AIR GAP RPM
Header full Patriot     1 7/8"
3 inch Exhaust
....................................................................
Cylinder Head Type:     Brodix race rite oval port
Intake Valve Diameter:    2.250 in.
Exhaust Valve Diameter: 1.880 in
...................................................................
Type of Camshaft:       Hyrdaulic Roller Lifters
Camshaft - Intake Duration @.050:       232
Camshaft - Exhaust Duration @.050:      244
Camshaft - Intake Lift at Valve:        595
Camshaft - Exhaust Lift at Valve:       581
Lobe Separation:        107
.....................................................................
The Spark Plugs are NGK V-Power  R5671A-7  Gap is .35
................................................................................................................
Federal Mogual Forged      :   .095 Dome Pistons
Felpro 1027 Head gasket   :   .039 thickness
Broddix Race Rite              :   119cc Chamber, 270cc Intake Runner 

 

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If it's running rich, I hope you are starting with the carb and timing. Fouled plugs are a byproduct. What size and type of carb? Jet sizes? Power valve? What is your timing at?

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Hello ,   Yes started with that. I can idle fine and driving around is ok she is just running rich. The 4 corner Mixture screws are out @2.5 turns and any further in and she drops alot of RPM when going into gear.Timing I've tried initial  @18 and @20 , Total ends up between 36 -38 both the same u. Its a Pro-System 950 Jets  I changed from 76 to  74 and PV-6.5. Specs for carb attached.  Hotter Plugs were one of the suggestions from Pro Systems.  Thank You 

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I have a 950 hp on my 496. More cubes, bigger solid cam, hooker super comp 2" headers and I have smaller jets than you. I honestly would down jet and of course change the plugs.

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So the plugs that I am looking at that are 1 range hotter are still NGK but the "Model" so to say is different. Everything else matches the only difference is they protrude into the chamber 2 mm farther than the ones I currently run.  I am a bit paranoid about putting longer plugs and hitting the piston. Or am I just being paranoid ? 

 

 

 
R5671A-7 / 4091 =  1. MM
BKR6E     / 6962 =  3 MM   ( New ones)
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