87 or 89 Unleaded?

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VPC20HD

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California
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Vincent
Truck Year
1982
Truck Model
C20 HD
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350/5.7/LT9
Hey everyone,

I have an 82 C20 that originally had a "M code" 350 sb with all the emissions stuff (California).

After research, my understanding is that you were only supposed to put 89 unleaded with that engine.

When my dad first purchase the truck, he didn't know this. He always put 87 and eventually had to replace the engine.

In 2006, he put in a new 350 crate engine from Chevy and hasn't really been driven since.

My question is, Do I still need to put 89 in it or am I good putting 87?
 

Ricko1966

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350
87 is fine better actually unless your 89 is ethanol free. More octane means more resistance to burn. Good for lighting preignition,but not better for making more power or better milage unless you tune specifically for the higher octane.
 

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