78 Corvette L48 Fuel Requirement

[Butch 714]

78 Corvette Owners Manual states use unleaded fuel but does not indicate which octane fuel is recommended.

Anyone with info and a reference to the requested data.

Thanks

Butch

[Joe L.]

Re: 78 Corvette L48 Fuel Requirement

Butch-----

During the 70s, most vehicles were designed to be operated on REGULAR unleaded fuel. As a matter of fact, in the early 70s and even into the later 70s, unleaded PREMIUM fuel was not even widely available. So, manufacturers could not build engines which REQUIRED the use of such fuel. As further "proof", for 1971 all Corvette engines used compression ratios of 8.5:1 or 9.0:1. In 1971 unleaded premium gasoline was an extreme rarity, particularly on the west coast.

For 1978, Corvettes with L-48 used an 8.5:1 compression ratio which is well within the capability of regular unleaded gasoline, so I doubt that premium fuel would have been required. Even for the L-82's 9.0:1, I think that regular unleaded would suffice under normal engine and operating conditions.

For practical purposes, you should use whatever fuel "your engine demands". If, under normal operating conditions, you experience little or no "ping" or pre-ignition and you are using 87 octane, then you're fine. If you do experience such conditions, then move up to mid-grade unleaded or premium unleaded, as necessary. Using higher octane than necessary is a waste of money and, while doing no harm other than that, does your engine no good, either.