91 vette timing?? confused
Thread Starter
Burning Brakes
Joined: Jun 2003
Posts: 949
Likes: 0
From: smithtown ny
91 vette timing?? confused
i was told my timing is set from the factory 6 degrees btdc so why are people telling me to set it 6-8 degrees advanced?? and what is the best way to set it at idle or higher???
Safety Car
Joined: Feb 2000
Posts: 4,230
Likes: 0
From: VA
Cruise-In II Veteran
Re: 91 vette timing?? confused (6spd)
Factory setting is 6 degrees if I remember correctly. It's on the label located in the engine bay some where. I set mine to 8 degrees, it gives it a little more go off the line. I tried 10 but I could here it detonating so I backed it off to 8 degrees.
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Re: 91 vette timing?? confused (6spd)
The timing is set to BTDC or Before Top Dead Center of #1 piston. It is sometimes stated as BTC or Before Top Center of #1 piston. On your Vette, look for the timing bar whick will be just to the drivers side of the front crankshaft. Looking at the bar, you will see a "0" and the words "before" and "after". The marks before are BTDC degrees. The "0" indicates top dead center of #1. Hope this is helpful!
[Modified by Sam Lam, 9:57 PM 4/8/2004]
[Modified by Sam Lam, 9:57 PM 4/8/2004]
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: 91 vette timing?? confused (6spd)
The first thing to do is toss the "frisbee" from the front of your water pump pulley so you can even see the timing marks.
Then unplug the EST connector in the Tan/Blk wire near the brake booster, brighten up the timing indicator plate with a little Scotch Brite or sand paper and put a mark at 6 & 8 deg BTDC.
Start the engine and check it out. Since the EST is open the ECM cannot vary timing so it should be the same at idle as any rpm.
I've found that I can run at 8deg BTDC with no knock retard; it gives a crisper throttle response and a little more on low end.
Then unplug the EST connector in the Tan/Blk wire near the brake booster, brighten up the timing indicator plate with a little Scotch Brite or sand paper and put a mark at 6 & 8 deg BTDC.
Start the engine and check it out. Since the EST is open the ECM cannot vary timing so it should be the same at idle as any rpm.
I've found that I can run at 8deg BTDC with no knock retard; it gives a crisper throttle response and a little more on low end.
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: 91 vette timing?? confused (6spd)
Stock is 6, but I run 8.
You can advance it as far as you want until you register knock, and youll get a little more power.
You can advance it as far as you want until you register knock, and youll get a little more power.
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
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
Re: 91 vette timing?? confused (vader86)
Anything before TDC(BTDC) is advanced and anything after TDC (ATDC) is retarded...its a little confusing when people tell you to retard or advance your timing. 8deg BTDC is advanced and so is 2deg BTDC(its just not as much advance). 2deg ATDC is retarded....
