Hei question
Thread Starter
Racer
Joined: Jan 2005
Posts: 307
Likes: 2
From: McCordsville Indiana
Hei question
My 74 coupe had been converted from points to hei by a previous owner,2 questions, Do I have to reset the spark plug gap from .035 to 0.60 and is the # 1 position on the distributor cap have to changed,different postion is shown for points ignition and hei position ?
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
...is the # 1 position on the distributor cap have to changed...
Last edited by Easy Mike; Apr 22, 2013 at 01:19 PM.
Le Mans Master
Joined: Oct 2006
Posts: 6,842
Likes: 285
From: Palmdale CA
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
.035" gap for points ignition with stock coil; .045" gap for most electronic ignition systems with higher potential ignition coils (ie, GM HEI system, Pertronix, etc.). Some high $$$ electronic systems advise you to go to .060" gap, but there is no real benefit in doing so.
For proper conversion from points to electronic ignition, you need to determine the proper way to get 12v power to the coil. The C3 points system used a [ballast] resistance wire to limit current to the stock coil. Many electronic systems MUST have a direct 12v supply source without a ballast resistor in the circuit. Many folks have improperly wired-up their electronic ignition systems and/or don't have a compatible ignition coil for that system.
For proper conversion from points to electronic ignition, you need to determine the proper way to get 12v power to the coil. The C3 points system used a [ballast] resistance wire to limit current to the stock coil. Many electronic systems MUST have a direct 12v supply source without a ballast resistor in the circuit. Many folks have improperly wired-up their electronic ignition systems and/or don't have a compatible ignition coil for that system.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
.035 gap is correct for points or electronic distributors....that is also where you get the best performance...that other dancing everywhere mid 70`s plug gaps was emissions orientated for those low HP engines and really didn't work there either and that's why .035 is better..
Tech Contributor
Joined: Jun 2004
Posts: 20,905
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
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