Great car - love the looks of the 70s & 71s. They were available with the 250 6, or 307,350,396 or 454 engines . . . . . and they were the years of highest compression ratios.
If you found one that is stock, it's bound to need high-octane fuel . . . . but most will have been modified over the years: previous owners could have changed compression, cams, or modified the valves/heads to run on unleaded gas. So it will really come down to knowing what has been done to each individual car.
You won't find a cheap one, I'm afraid . . . if you're looking for a genuine, original SS with a factory hi-po engine, it will cost a LOT. If you're looking for a driver, there are a lot of clones out there for less money, with and without the big motors.
You didn't state which engine but your choices bach then were Regular or Ethyl, the equivalent of today's Regular or "premium" etc. Cars have always taken the same gasoline, the only difference today being the addition of methanol. You did not state your altitude but you could start with premium (high octane--it should be fine) then go down to midgrade, then to regulare 87 octane. Then use the one that produces least perceptible knock (and fuel expense) and stay with that. With 70 stock Chevy Chevelle, Regular unleaded will probably be okay. Cars back then tended to rely on 8 cylinders, fuel delivery (by quad carb...) and engine displacement for "muscle" more than fuel compression. "Hi test" (high octane rated) gasoline tended to be restricted to the huge, very heavy "luxury boats," just to get them moving along silently.
A 1970 450 horse 454 uses 103 octane leaded fuel.
And don't forget the can of lead additive every fill up, for 60's and early 70's cars.
depending on the engine. If it's high compression, it need premium
when i get older im going to buy a 1970 chevelle. i was just wonderin, what kind of gas do i have to fill it up with, regular super etc?
