Hello,

I am new to the forum and a new Monte Carlo owner. I just purchased as 1970 with a 400/2 Barrel. The car has 41,444 original miles and is all original. The previous owner ran 87 with a lead additive. My friend who has a 67 Vette and has had many old cars, says the new fuels have enough lubrication w/o the lead. Any suggesstions. Thanks

 

I see lots of old cars riding around using modern gas, I don't know if there's a special conversion they have to undertake or not in order to take unleaded gas, but I would be cautious when using it, and to only use 87, 89 and up may have adverse effects.

 

I believe the issue with the unleaded gas has to do with the valve seals cracking. you could replace them to run a modern fuel. octane isnt that huge of a deal if your not running high compression. i dont think any of the 400sbc were ever real high compression motors. im almost running 11:1 on my 406 and i dont ping but then again im running 93 octane.