C3 General General C3 Corvette Discussion not covered in Tech
Sponsored by:
Sponsored by:

Spark plug gapping....

Thread Tools
 
Search this Thread
 
Old Nov 13, 2007 | 07:20 AM
  #1  
ShaneLU97's Avatar
ShaneLU97
Thread Starter
Drifting
10 Year Member
 
Joined: Aug 2004
Posts: 1,677
Likes: 1
From: Potomac Falls VA
Default Spark plug gapping....

Would like to replace my plugs in my 383 and I have all the shop manuals for my car. Even though the vette never came with a 383, can I use the same gapping as listed in the manuals?
Thanks
Shane
Reply
Old Nov 13, 2007 | 07:42 AM
  #2  
sweethence's Avatar
sweethence
Le Mans Master
10 Year Member
 
Joined: Jan 2006
Posts: 8,319
Likes: 7
From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
Default

normally yes,

but if you are runnning and an HEI ignition you can open the gap up to as much as .050 depending on the application. Though generally i would say .045 is right for most HEI applications



tim
Reply
Old Nov 13, 2007 | 08:30 AM
  #3  
ShaneLU97's Avatar
ShaneLU97
Thread Starter
Drifting
10 Year Member
 
Joined: Aug 2004
Posts: 1,677
Likes: 1
From: Potomac Falls VA
Default

Originally Posted by sweethence
normally yes,

but if you are runnning and an HEI ignition you can open the gap up to as much as .050 depending on the application. Though generally i would say .045 is right for most HEI applications



tim
Great, thanks. I forgot about the HEI and that is a good point. Would you happen to know of a good primer on the subject?
Reply
Old Nov 13, 2007 | 09:13 AM
  #4  
sweethence's Avatar
sweethence
Le Mans Master
10 Year Member
 
Joined: Jan 2006
Posts: 8,319
Likes: 7
From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
Default

Originally Posted by ShaneLU97
Great, thanks. I forgot about the HEI and that is a good point. Would you happen to know of a good primer on the subject?
I only know the old rules of thumbs off the top of my head, i.e when you raise compression or go to forced induction you must reduce the gap about .004 for every 50 hp. And when you add an HEI you can open the gap from .002-.005 from standard, with some aftermarket ingition companies ( mallory, DUI, etc) claiming you can open up to .055 depending on application. I run a DUI HEI unit at .040, and then read the plugs and adjust from there. It seems happy at .040 so thats where i keep it


some more expert techs please chime in
tim

Last edited by sweethence; Nov 13, 2007 at 09:15 AM.
Reply
Old Nov 13, 2007 | 09:40 AM
  #5  
capevettes's Avatar
capevettes
CF Community Team
Supporting Lifetime
20 Year Member
Active Streak: 90 Days
Active Streak: 120 Days
Conversation Starter
 
Joined: Oct 2004
Posts: 19,365
Likes: 5,244
From: Cape Cod, Mass.
2025 C6 of the Year Finalist - Unmodified
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
2021 C8 of the Year Finalist Unmodified
2020 Corvette of the Year Finalist (performance mods)
2019 C1 of Year Winner (performance mods)
2017 Corvette of the Year Finalist
2016 C2 of Year
2015 C3 of Year Finalist
Default

I run .040 in my 383 in my 61 with HEI. Seems to burn well. NGK's.
Reply

Get notified of new replies

To Spark plug gapping....





All times are GMT -4. The time now is 04:16 PM.

story-0
10 Ugly Corvettes That We Still Kinda Love

Slideshow: 10 ugly Corvettes that we still kinda love.

By Joe Kucinski | 2026-06-03 10:34:17


VIEW MORE
story-1
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer

A lot of money has changed hands at the online auction house over the years.

By Brett Foote | 2026-06-03 10:21:50


VIEW MORE
story-2
10 Things Every Corvette Owner Needs (2026 Edition)

Slideshow: 10 great gifts Corvette enthusiasts actually want for Father's Day!

By Michael S. Palmer | 2026-06-03 15:43:40


VIEW MORE
story-3
8 Most "Only Corvette Owners Understand" Quirks and Problems

Slideshow: These are the quirks, annoyances, and oddly lovable problems that every Corvette owner eventually learns to live with.

By Pouria Savadkouei | 2026-05-28 09:31:39


VIEW MORE
story-4
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

Slideshow: 10 reasons why the C6 Z06 is still a performance benchmark after 20 years.

By Joe Kucinski | 2026-05-27 17:20:09


VIEW MORE
story-5
How Much Horsepower Every Corvette Engine "LOST" in 1972

Slideshow: How much horsepower every Corvette engine lost in 1972.

By Joe Kucinski | 2026-05-27 16:54:53


VIEW MORE
story-6
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

Slideshow: How to Protect A Convertible Top: 10 DOs & DON'Ts

By Michael S. Palmer | 2026-04-03 00:00:00


VIEW MORE
story-7
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

Slideshow: The 10 most explosive Corvettes ever built based on power-to-weight ratio.

By Joe Kucinski | 2026-05-20 07:23:03


VIEW MORE
story-8
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-9
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE