mikethibault

What type of gas should be put in a 1969 corvette?

bluthundr

While this sticker was probably on the car when it was new



Realistically, use the lowest octane fuel that does not cause any pinging or misfires. There is no magic answer. What engine you have, timing, heads, etc all play a factor.

Alan 71

Hi b,
Were you kidding? I believe the octane warning sticker only appeared on cars with the L-88 option.
Hi Mike,
I think the queston now is whether a lead additive needs to be used or not. Others know more about that than I do, and I'm sure you'll get some replies.
Regards,
Alan

Ironcross

6500 red line, use 93, any thing less than 6500, then 87-89 octane should be all that's necessary.....don't use additives as they don't work and merely make the price of the pump gas more expensive

couperdecar

I'd use anything without ethanol in it. That stuff is horrible for older vettes ! Plus if you use the 10% stuff - you lose about 5% of your mileage.

mikethibault

Ultra 94 from Sunoco shoud be OK. So, I should not add any "octane booster" to it?

bluthundr

Wasn't there some other type of fuel type note that was a tag attached to the radio?

mikethibault

I guess I should be asking if I should be adding a lead additive or octane booster or both. Was there "unleaded" gas available in 1969? I thought there was only "leaded" gas in 1969.

CA-Legal-Vette

The was no unleaded fuel in 69. It came out when they added catalytic converters.

Are your heads and valves original? The valve seats are where you might run into trouble but I'm not sure thact adding lead additive will get you very far.

Easy Mike

Alan is correct; only the L-88 cars got the octane warning sticker on the console. They also had a How To Start tag with them warning there was no choke.

If a fuel advisory sticker was placed on the car at the factory, the AIM will show it and list the GM part number. The catcon cars usually had a notice about unleaded fuel, but placement of the notice could vary between model years.

Vette5.5

The posted sticker actually equates to 99 octane today, so if running an ultra high compression car like that, get the highest rating premium and probably mix in some racing fuel. It does matter, as have some high compression cars, and when fuels in the tank for awhile with octane dropping, car just doesnt have the intended power. The premium labels weren't only Vette thing, as recall seeing them on many cars from that era, when shopping with my dad. Unleaded came out before 75' cats, as GM dropped compression in 71' to use it.

Mike Ward

No Corvette ever required lead in the fuel to avoid valve seat damage, that's an old myth that won't die. Use the minimum octane gas that will preclude detonation.

larrywalk

Also can only get E-10 here is Missouri and that works well too.

Vette5.5

Nothing wrong with E10, as ethanol actually has high higher octane rating, but less BTU(energy) than gas. Maybe look into a little carb re-jetting to optimize it though. To much alcohol isn't doing rubber hoses any favors though. Indy and other race series run pure alcohol, so gotta be something to it. We've all heard of E85, which is still 15% gas. Main reason, is you can't these cars to start winter time without it. Actually closer to E80, as the denatured ethanol used is already poisoned with 5% gas for drinkability, and the bootleggers aren't wanting trucks carrying raw product from the distilleries.

694speed350

amoco had unleaded back then. As far as lead additives I searched recently and couldn't find any. My '69 runs fine on 93 octaine 10.25 compression you can run lower but may have to retard timing to keep from pinging and lose performance. the other boosters are useless.

cottoneg

OK, I did take down the heads down twice for a cleaning cut. Plus I did have the distributor curved. My 69 engine (350/350) had an 11 to 1 compression ratio and I used Sunoco 94. When I took the engine apart for rebuild, there was detonation damage to the forged pistons. You could see the small chips that were missing due to detonation. Maybe I didn’t hear it due to the load exhaust. But there was definitely detonation damage.

I am not so sure Sunoco 94 is enough unless you do all the things that reduce detonation like running a cooler thermostat and retarding your timing (which will hurt gas mileage and performance).

cottoneg

http://forums.corvetteforum.com/c3-t...injection.html