Have been running high Octane fuel per the Rivieras Car Manual. Does anyone know if plain old regular 87 Octane will work or cause any negative effects? Thank you Dan
Mine do not like the 87 or even 89 octane. Others may be different and may have different compression ratios.
If you use 87, the engine may ping or detonate. Probably the most injurious thing for an engine. Having said that, if you drive it like a little old lady, you'll probably be fine.:grin: I frequent a board for the 95-99 Riviera. Some guys over there ask the same question. They want to run 87 despite the fact that the owner's manual recommends 91 octane minimum for supercharged engines. There is even a sticker on the inside of the fuel door that says, "Premium Fuel Only). Of course there are guys who say they are doing it successfully, but to me, that's extremely foolish. There are no shortage of threads detailing spark plug and piston damage and the cause is detonation. Mostly, it's guys thinking they can just use smaller pulleys for more boost without monitoring Knock Retard. The PCM will retard timing when the knock sensors detect knock. That is an attempt to protect the engine, but the PCM can only do so much. The Nailheads have no such defense, be careful.
You can try the 87 and listen for ping under various conditions... light acceleration and full throttle. If you hear it pinging you're on the way to some expensive engine repairs! You can't always easily hear the ping/detonation, so be careful. You may be able to tune it to run on lower octane by retarding the mechanical and vacuum timing advance, which is also likely to decrease engine performance and gas mileage! Water injection and methanol injection is another way to reduce detonation.
According to the 1966 Buick Chassis manual, 2 bbl equipped engines required regular gasoline while 4 bbl engines required premium. In the mid 60's, I believe regular gas was around 93-94 octane, premium was closer to 100.
My '64 Wildcat will ping with 89 octane when pushed hard. I recently fueled up with 89 octane by mistake and noticed the pinging under hard acceleration. I drove her carefully until I could fuel up with 93 octane.
well there was a 375 low comp 2 bb that may be able to run it. the high comps prob need 93. there was a low comp and high comp 2 bb so it makes a difference.
