older high compression engines
Le Mans Master
Joined: Apr 2005
Posts: 6,355
Likes: 425
From: Seattle Area WA
Your '69 350/350 should run fine on 92-93 octane gas. I have basically the same configuration as yours in the 350 I built for my kids 1976. Measured 10.25:1 static compression, 1969 heads without hardened seats and a L79 "151" cam (because thats what I had laying around) verses the L46 cam your engine has. They both bleed off enough compression to result in an acceptable Dynamic compression for 92 octane. I'm also running a tunned Q-jet with some tips from Lars and 36 degrees all in by 3,000 RPM.
Last edited by Scott Marzahl; Mar 1, 2011 at 06:03 PM.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Your '69 350/350 should run fine on 92-93 octane gas. I have basically the same configuration as yours in my engine, 10.25:1 static compression, 1969 heads without hardened seats and a L79 "151" cam verses the L46 cam your engine has. They both bleed off enough compression to result in an acceptable Dynamic compression for 92 octane. I'm also running a tunned Q-jet with some tips from Lars and 36 degrees all in by 3,000 RPM.
Thread Starter
Race Director
Joined: Sep 2005
Posts: 18,640
Likes: 121
From: Farragut,TN
It does however I burn 93 octaine now have no problems. that is not the point. would like the tereathel lead in the gas for the lub for the valves and maybe to be onery.
Le Mans Master
Joined: Apr 2005
Posts: 6,355
Likes: 425
From: Seattle Area WA
You don't need lead for valves, its a wives tale. The only time it does any good is during break-in after a new valve job without hardened seats, the lead works itself into the cast iron. The cast iron itself work hardens very quickly and after a tankful or two of leaded gas the job is done.
Racer
Joined: Jan 2011
Posts: 266
Likes: 0
From: York Pa.
I am in the same boat as you..I played with the tune of the car for a couple of weeks off and on..I gave up at the point that its as good as it gets..before the fall hit I was driving around town and found some gas at a shell station..I can't remember if it was called cam 2 or not but that sticks in my head..it was 110 octane..after 2 minutes of running the car took off..and had that sweet smell..I had about a half tank and popped another 6 gallons I think in it..I think this may be the best way to get what you want..as suggested on a previous post..mix it or run it straight..I am not sure why the old heads like ours wouldnt need the lead? If they don't have hardened seats then don't the valves pound into the head? I am curious if anyone knows for sure when the seats are hardened from the start..
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
Local vette shop buys C12 in 55 gallon drums. One gallon per 10 gallons of 93 pump gas will make your engine happy.
http://www.vpracingfuels.com/
http://www.vpracingfuels.com/
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
For the umpteenth time- the valve seat issue does NOT apply to Corvettes.
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: Apr 2005
Posts: 6,355
Likes: 425
From: Seattle Area WA
No, GM testing has shown that heavy duty service vehicles that see heavy duty towing and hauling or hard core racing vehicles may benefit from hardened seats.
Induction hardened seats were standard beginning 1973.
Induction hardened seats were standard beginning 1973.
Last edited by Scott Marzahl; Mar 2, 2011 at 12:22 AM.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
1971-2011, happy 40th anniversary hardened valve seats!
Whooops, my aluminum beanie almost slipped, can't let the aliens read my thought waves!
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
As stated further up, the hardened seats were first introduced in calender year 1970, so all 1971 and up Corvettes (and other GM cars) had them. The much feared deletion of lead did not cause mass degradation in durability, yet the legend lives on 4 decades later..............
1971-2011, happy 40th anniversary hardened valve seats!
Whooops, my aluminum beanie almost slipped, can't let the aliens read my thought waves!
1971-2011, happy 40th anniversary hardened valve seats!
Whooops, my aluminum beanie almost slipped, can't let the aliens read my thought waves!
I didn't see an email addy for you & I don't fool w/ IM etc ...
there's a pleasant site quite near me where Theophilus Ward established a (grain) mill in 1700's; he & wife repose in thicket within a few hundred yards and he was also a Rev war officer ... Ward was a whig, not a tory. Some of the old mill brickwork remains at site. Local Ward plans to submit paperwork for historic site status. There's a small bridge overlooking site ... I manually acquired this GPS from atop that bridge along SC state road S-21-55 (aka Meadow Prong RD).
N 34° 01.761' aka N 34.02936°
W 79° 48.964' aka W 079.81612°
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
As stated further up, the hardened seats were first introduced in calender year 1970, so all 1971 and up Corvettes (and other GM cars) had them. The much feared deletion of lead did not cause mass degradation in durability, yet the legend lives on 4 decades later..............
1971-2011, happy 40th anniversary hardened valve seats!
Whooops, my aluminum beanie almost slipped, can't let the aliens read my thought waves!
1971-2011, happy 40th anniversary hardened valve seats!
Whooops, my aluminum beanie almost slipped, can't let the aliens read my thought waves!
Welcome to the C3 section. I've learned not to second guess an OP on a question. My brain is not creative enough to know that they really mean 123 when they ask ABC, I'll leave that up to the guys that have recommended the non-lead containing additives that reduce valve guide wear. 
Last edited by 63mako; Mar 2, 2011 at 01:24 PM.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Edit: Better yet, just block my posts OK?
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Mike Ward:
I didn't see an email addy for you & I don't fool w/ IM etc ...
there's a pleasant site quite near me where Theophilus Ward established a (grain) mill in 1700's; he & wife repose in thicket within a few hundred yards and he was also a Rev war officer ... Ward was a whig, not a tory. Some of the old mill brickwork remains at site. Local Ward plans to submit paperwork for historic site status. There's a small bridge overlooking site ... I manually acquired this GPS from atop that bridge along SC state road S-21-55 (aka Meadow Prong RD).
N 34° 01.761' aka N 34.02936°
W 79° 48.964' aka W 079.81612°
I didn't see an email addy for you & I don't fool w/ IM etc ...
there's a pleasant site quite near me where Theophilus Ward established a (grain) mill in 1700's; he & wife repose in thicket within a few hundred yards and he was also a Rev war officer ... Ward was a whig, not a tory. Some of the old mill brickwork remains at site. Local Ward plans to submit paperwork for historic site status. There's a small bridge overlooking site ... I manually acquired this GPS from atop that bridge along SC state road S-21-55 (aka Meadow Prong RD).
N 34° 01.761' aka N 34.02936°
W 79° 48.964' aka W 079.81612°
Most Wards in North America came from England, whereas my family came from N. Ireland. The original family name before it was 'anglicized' was 'Mac an Bhaird' which has been traced back to the third century AD and has roots in the word 'bard', a writer or poet. As witnessed above some people don't care for my style of writing and take everything as personal insults and attacks.
Guess we know who's lost their beanie, huh?
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Do you have any on-topic thoughts to share?
Think about it.
