I have a 79 cutlass with a 69 350 rocket it has an edlebrock performer hi rise intake, thunder series avi edelbrock 650 4brl carb and a somewhat mild crane cam. My question is what grade of fuel should I be running I've been switching between mid grade and premium. It seems to me it doesn't run ad good on mid grade should I be running premium?

 

I think it depends on the engine's compression ratio. Both low and high-compression versions of the 350 were available in 1969 Cutlasses, and the former used regular fuel while the latter required premium. If your engine runs better on premium, that's probably what you should be using.

The stock low-compression 350 came with a 2-bbl carb while the high-compression came with a 4-bbl. If you know what carburetor was on your engine originally, that would tell you which engine you have.

 

And while we're all at it I'd like to know what people's recommendation is for 91 non-ethanol vs 93 10% ethanol (I can't get 93 non-ethanol around here). I've heard that ethanol retards detonation. My carb has been rebuilt with a modern ethanol resistant kit so that's not an issue. I generally run the 93 in it without any issues and the 91 is at least $.30 more a gallon.

 

The 91 no ethanol or the 89 ethanol would work fine.

 

ok im not sure which motor it has i guess it comes down to vin. i could try a diffrent plug and stay at midgrade and see if anything changes.. also while we are talking. whats your opinions on headers? An olds specialist here in town although they do no performance said that if I put headers on that I would be changing gaskets all the time. Is there any validity to that? And if I was to run headers what brand? And should they be shorties? Exhaust wise i have 2 inch duals all the way back with resonators. Its way to loud so im thinking of putting some flowmasters on it and maybe going a little bigger on the exhaust

 

My car has had Heddman Headers since 1982 and I never had a header gasket fail. I might have had a collector gasket leak but that may have been caused by messing around with the exhaust pipes.

 

Thanks fun71!

 

Unfortunately, no. You of course need the VIN of the car the engine came out of, and in 1969, the VIN only indicated whether or not the car had the L-6 engine or a V-8. It would not tell you anything about which V-8.