Spark advance
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.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
All the specs for the dozen-or-so distributors that were used in whatever car and year you're working on are shown in the "Specifications" section of your Service Manual.
...But why anyone would try to duplicate those specs would be the question. The original specs were established in order to pass federal emissions requirements, and to de-tune the engine enough that warranty claims would be reduced. The specs were further developed for the gasoline blends that were used in the 1970's (assuming you have a 1970's car), which are no longer available or used. Tuning a car to those specs is simply a bad idea, and will result in an exceptionally poorly-running vehicle. You should tune the car (distributor) to specs that are suitable for good performance and to accommodate the fuels that are currently available.
Since you haven't filled out your profile, and have not stated what type of car you have, what year it is, what engine you have, what mods you have, or what type of ignition system you have, it's impossible to provide you with any recommendation at all.
Last edited by lars; May 19, 2025 at 07:10 PM.
Thread Starter
4th Gear
Joined: May 2025
Posts: 4
Likes: 0
From: Marmora Ontario Canada
I have an l82 build in an 80 Camaro. Initial set at 12 distributor has 24 so 36 total without vacuum at 3500rpm. I know it should be all in earlier but what I was looking for was is should the curve come in sooner or later ?
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Set it up so that the full, total, pegged-out 36 degrees comes in at 2800-3000. That will provide a very nice level of performance with no detrimental effects. Limit your vacuum advance to add no more than 12 degrees. The 3500 spec you have is not bad, but you can gain just a little torque in the mid-range by bringing it in a tad quicker.
Lars
Lars
Thread Starter
4th Gear
Joined: May 2025
Posts: 4
Likes: 0
From: Marmora Ontario Canada
With one weaker spring I am pinging on hard acceleration so back to two silver springs. Idles nice at 14 degrees so I might have to find a way to limit the mech advance a couple of degrees.
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
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
When you set up the mechanical advance properly, whatever you end up with at idle is where you want it. You can end up with higher spark advance numbers if your idle speed is set too high, as well.