spark plugs
Thread Starter
Racer
Joined: May 2021
Posts: 331
Likes: 15
From: Las Vegas
spark plugs
I know there are different spark plugs for my 77 vette with the 350 block. I also have the long tube headers on it. I would like a plug that is the best as far as performance . What would you recommend? Thank you.
Race Director
Joined: Nov 2006
Posts: 13,227
Likes: 7,823
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Which heads? Compression ratio?
If your engine is mostly stock. Just look them up on the chart. And yes. NGK.
If your engine is mostly stock. Just look them up on the chart. And yes. NGK.
Race Director
Joined: Nov 2006
Posts: 13,227
Likes: 7,823
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Header's won't change plug requirements. Just run a good quality spark plug. Myself, I've had the best luck with NGK. I don't have stock heads on my 77 so I won't recommend the plugs I run. Simply look them up in there replacement charts.
And my condolences on the factory heads.
And my condolences on the factory heads.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I ran the NGK UR45 with my headers when I ran the stock/cast iron heads. Worked good. They're a little hot, depends on your driving. You could always try UR55 if you have issues. But with low compression engine IE 8.0:1 or so theUR45 worked good at my altitude. If you're at or near sea level the UR55 may be more appropriate.
https://www.ngk.com/ngk-2248-ur55-v-power-spark-plug
https://www.ngk.com/ngk-2248-ur55-v-power-spark-plug
Last edited by REELAV8R; Nov 22, 2021 at 09:38 AM.
Safety Car
Joined: Sep 2005
Posts: 4,226
Likes: 643
From: Orange County Ca
I've found that the cheap, copper plugs run just as well as any high $$$ plugs. They may not last as long, but with unleaded gas, they can still go 20k miles.
The right heat rating and correct length is more important.
Ok, well, I don't buy Champion, as they had major quality control problems in the past.
The right heat rating and correct length is more important.
Ok, well, I don't buy Champion, as they had major quality control problems in the past.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
I ran the NGK UR45 with my headers when I ran the stock/cast iron heads. Worked good. They're a little hot, depends on your driving. You could always try UR55 if you have issues. But with low compression engine IE 8.0:1 or so theUR45 worked good at my altitude. If you're at or near sea level the UR55 may be more appropriate.
https://www.ngk.com/ngk-2248-ur55-v-power-spark-plug
https://www.ngk.com/ngk-2248-ur55-v-power-spark-plug
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,579
you make no mention if you have a clearance issue because of the headers. If you do, look at Accel, they make short plugs for header applications.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
one range colder.
NGK lower number is hotter higher number is colder
https://www.ngk.com.au/technical_info/heat-range/
NGK lower number is hotter higher number is colder
https://www.ngk.com.au/technical_info/heat-range/
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
one range colder.
NGK lower number is hotter higher number is colder
https://www.ngk.com.au/technical_info/heat-range/
NGK lower number is hotter higher number is colder
https://www.ngk.com.au/technical_info/heat-range/
Thread Starter
Racer
Joined: May 2021
Posts: 331
Likes: 15
From: Las Vegas
I ran the NGK UR45 with my headers when I ran the stock/cast iron heads. Worked good. They're a little hot, depends on your driving. You could always try UR55 if you have issues. But with low compression engine IE 8.0:1 or so theUR45 worked good at my altitude. If you're at or near sea level the UR55 may be more appropriate.
https://www.ngk.com/ngk-2248-ur55-v-power-spark-plug
https://www.ngk.com/ngk-2248-ur55-v-power-spark-plug
Thread Starter
Racer
Joined: May 2021
Posts: 331
Likes: 15
From: Las Vegas
What do you think about the NGK 7401 ? expensive plug though. I'm just looking for the best plug for my mildly stock 350 block. Like i said before its a 350 L82 block with the stock heads, headers, and edelbrock manifold with a 600 cfm. The only thing I have done is change the gears from 370 to 390. Thanks for your help.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
its wrong. Just gap it correctly.
I see that you can just buy the ur4 or ur5 and the only difference is the gap. But whichever is available, or cheaper. You got to check the gap no matter which you buy in any case.
I see that you can just buy the ur4 or ur5 and the only difference is the gap. But whichever is available, or cheaper. You got to check the gap no matter which you buy in any case.
Last edited by REELAV8R; Nov 23, 2021 at 09:44 PM.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
What do you think about the NGK 7401 ? expensive plug though. I'm just looking for the best plug for my mildly stock 350 block. Like i said before its a 350 L82 block with the stock heads, headers, and edelbrock manifold with a 600 cfm. The only thing I have done is change the gears from 370 to 390. Thanks for your help.