Correct Fuel for 72 Small Block
Melting Slicks
Joined: Jan 2002
Posts: 2,075
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
Compression ratio was lowered on all engines in 1971. If you have L-48 engine, it will run on regular unleaded just fine. If you have the LT-1, it will need either mid-grade or premium fuel, depending how you tune the engine (timing).
Burning Brakes
Joined: Sep 2016
Posts: 944
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From: Dutchess county New York
A new set of points & condenser was actually the correct investment for the problem I was having but I'm mentioning this here because Walmart online has some good prices on the Torco stuff if you want to go looking for any. It was about $22 delivered.
Burning Brakes
Joined: Sep 2016
Posts: 944
Likes: 436
From: Dutchess county New York
Some will swear by this stuff no matter what so I was just passing along a little comparison shopping
Last edited by pigfarmer; Jul 25, 2018 at 10:05 AM.
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Drifting
Joined: Nov 2000
Posts: 1,390
Likes: 39
From: North Brunswick NJ
I have had my 72 SB since new. This car was originally designed for low lead fuel. I am not sure and dont remember how much lead was still in low lead fuel, as no lead fuel was not readily available at all gas stations. This was the second year of hardened valve seats, so that low lead fuel would not damage the valves and seats. So with all that said if the engine did not have work done to change the cr, you can use regular grade fuel. If it pings under load, then you should try med grade or high test/
Ed
Ed
Last edited by ED DINAPOLI; Jul 26, 2018 at 10:18 AM.
Racer
Joined: May 2011
Posts: 423
Likes: 93
From: Mechanicville NY
Guys,
i have always used 93 or better octane in my tank, makes the car runs better, less pinging, more power. I will on occasion put in a little leaded racing fuel in her (3-4 gallons) to give her a treat.
i have always used 93 or better octane in my tank, makes the car runs better, less pinging, more power. I will on occasion put in a little leaded racing fuel in her (3-4 gallons) to give her a treat.
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,053
Likes: 4,405
From: Marlton NJ
Huge range of possible answers here.
Basically it all depends on your compression ratio and the tune-up.
The engine may or may not still be stock after 4 decades.
The simple answer is Run as much octane as it needs to keep it from pinging and running smoothly.
Experiment with octane a little bit, if it pings, drive it gently, and add more soon til it stops.
More octane than that does not help.
If it still pings on whatever gas you are running, change the tune-up.
71s and newer were originally built for unleaded gas, and either 87 or 93 octane depending on the engine.
70s and older need leaded gas or additives or newer hardened valve seats, plus higher octane, if still stock.
(Chemist and race car mechanic)
Basically it all depends on your compression ratio and the tune-up.
The engine may or may not still be stock after 4 decades.
The simple answer is Run as much octane as it needs to keep it from pinging and running smoothly.
Experiment with octane a little bit, if it pings, drive it gently, and add more soon til it stops.
More octane than that does not help.
If it still pings on whatever gas you are running, change the tune-up.
71s and newer were originally built for unleaded gas, and either 87 or 93 octane depending on the engine.
70s and older need leaded gas or additives or newer hardened valve seats, plus higher octane, if still stock.
(Chemist and race car mechanic)
