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Nick_R_23 · 11-23-2021, 07:46 AM

If it’s only recommended, then no, it’s not completely required, but you may run into high load situations like hill climbing, towing, hauling heavy loads, etc that may push you into detonation territory. Running conservative timing will help suppress that, but you also may not be getting full potential from your engine.

In a previous industry I was in, it was advertised as 87 min/91 rec. This means you could run as low as 87, but the ECM would pull timing using fuel rated below 91. 87 was just the max it would compensate to.

11-23-2021, 07:46 AM	#5
Nick_R_23 Registered User Join Date: May 2016 Location: Willow, Alaska Posts: 839	Re: GM crate 350 HO runs fine on regular 87? If it’s only recommended, then no, it’s not completely required, but you may run into high load situations like hill climbing, towing, hauling heavy loads, etc that may push you into detonation territory. Running conservative timing will help suppress that, but you also may not be getting full potential from your engine. In a previous industry I was in, it was advertised as 87 min/91 rec. This means you could run as low as 87, but the ECM would pull timing using fuel rated below 91. 87 was just the max it would compensate to.