What spark plug to use - The 1947 - Present Chevrolet & GMC Truck Message Board Network

65k10 · 12-03-2020, 10:30 PM

Howdy,

trying to dial in my new(ish) 383. Engine was built a couple years ago and has seen little use but now truck is together and ready to become the daily driver. Engine builder may have taken a few shortcuts at the end and not sure if these are the best plugs to use (may have been what was laying around the shop!) I've sorted out all the other gremilins and this is the last thing to figure out. Engine is 9.5 to 1, pump gas, Brodix heads and intake, full length hooker headers and 2.5 inch exhaust, Edlebrock 1406 600cfm, mild cam, and HEI with 8.5mm MSD wires.

The plugs in it are NGK R5671A-8 non-resistor. It idles a little erratic but runs like a scalded dog when you punch it. Got more power than I expected which is not a bad problem to have. I have had a couple plugs go bad, not foul out, but just go bad, so no I'm thinking maybe these plugs aren't the best choice.

Any advice is appreciated.

**Captainfab** · 12-03-2020, 11:02 PM

What does Brodix recommend for the model of heads you have?

65k10 · 12-04-2020, 12:01 AM

Suddenly that seems so obvious lol! I feel a little stupid. Went to their site and sure enough the info was all there. Turns out these plugs are for race gas. The plugs they recommend for pump gas are Champion RN12YC. Guess I'll be hitting the parts store tomorrow.

Thanks again!

12-03-2020, 10:30 PM	#1
65k10 Registered User Join Date: Apr 2013 Location: Las Vegas Posts: 12	What spark plug to use Howdy, trying to dial in my new(ish) 383. Engine was built a couple years ago and has seen little use but now truck is together and ready to become the daily driver. Engine builder may have taken a few shortcuts at the end and not sure if these are the best plugs to use (may have been what was laying around the shop!) I've sorted out all the other gremilins and this is the last thing to figure out. Engine is 9.5 to 1, pump gas, Brodix heads and intake, full length hooker headers and 2.5 inch exhaust, Edlebrock 1406 600cfm, mild cam, and HEI with 8.5mm MSD wires. The plugs in it are NGK R5671A-8 non-resistor. It idles a little erratic but runs like a scalded dog when you punch it. Got more power than I expected which is not a bad problem to have. I have had a couple plugs go bad, not foul out, but just go bad, so no I'm thinking maybe these plugs aren't the best choice. Any advice is appreciated.

12-03-2020, 11:02 PM	#2
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,246	Re: What spark plug to use What does Brodix recommend for the model of heads you have? __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

12-04-2020, 12:01 AM	#3
65k10 Registered User Join Date: Apr 2013 Location: Las Vegas Posts: 12	Re: What spark plug to use Suddenly that seems so obvious lol! I feel a little stupid. Went to their site and sure enough the info was all there. Turns out these plugs are for race gas. The plugs they recommend for pump gas are Champion RN12YC. Guess I'll be hitting the parts store tomorrow. Thanks again!



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