rsmith31

Pardon my ignorance, but I've just bought a 1973 SB & was wondering what fuel should be used (unleaded or leaded) & what octane rating?

Russell

Pauld

Definately unleaded and just regular unleaded will be ok.

Pauld

And welcome to the world of Corvettes

c3andc5

I use Super Unleaded...never less then 91 Octane. Your Q-Jet will appreciate it.

rsmith31

Thanks for your help guys. I get my car next week (arrived in Brisbane from Florida yesterday) & wanted to make sure before I put the right fuel in.

carl a

you picked a great year!--welcome--

gerry72

Wow, guys. There were two smallblocks in '73 and the answer depends on which smallblock he has (unless I'm messed up and somehow missed where he wrote that).

If you have the L-48, then you should do just fine on regular unleaded 87 octane.

If you have the L-82, then it would be iffy in anything but 89 or higher unleaded.

Either engine greatly depends on how the engine is tuned. You can make an L-82 run fine on 87 and you can make an L-48 need 89 or higher if the tuneup isn't right or at least in the ballpark. The altitude where you are also plays a part. High elevations don't need as much octane.

I suggest that you try the lower octane and see how she does.

carl a

the difference is 180 hp v 225 hp- both will run on regular gas

gerry72

Not quite, Carl. The octane tolerance threshold difference is in the compression and cam. And your power numbers are wrong for '73.

carl a

111190 hp and 22225 instead of 1811110 and 2222225 sorry i hit the wrong key

Mike Ward

All '73s were designed to run on regular unleaded gas, irrespective of displacement or horsepower ratings.

GDaina

If leaded is available in your corner of the world, lead

c3andc5

Still wrong if you're talking 73 small blocks. 190 hp for the L-48 and 250 hp for the L-82.

Yellow73SB

I use 100 octane leaded

vabeachvette

Since having mine I have used the expensive stuff, lots of good threads on this topic (cause' I looked at them when I had the same question) using the archive search function. Have at it and take a read.

ruby76

the q-jet won't care one bit. However, the combustion chambers could care if it's hight compression. run 87octane, if you hear pinging or pre-detonation, check timing, if it's okay, then go up an octane rating till it stops.

bitner23

my original GM sticker located on the underside of the battery compartment door states "91 octane or higher" on my 73 L-48 ?

ffas23

This quote is somewhat true but regular gas in 1973 was 95 octane and high test depending on where you purchased it was from 101-104 Octane. Sunoco was the only gas station to offer their Sunoco 260 blend which was 104 Octane. The actual color of Sunoco 260 gasolene was blue. Unleaded gas although Amoco originally sold it wasn't mandatory until 1975 in the states when it was required in all 75' and up cars.

Fred

cosmicvette

Hi Russel,
Welcome to the forum! Another Aussie...thats awesome
Im from Sydney.

Congrats on your new vette...it looks real nice (your avatar pic?).

Im still waiting for my vette to arrive..I don't think it has left Los Angeles yet!

When your vette arrives, post us some pics! and tell us more about it.

Im sure you will have alot of fun with your vette. Look forward to hearing more about it.


cosmicvette

fauxrs2

Use whatever gas allows you to drive without pinging! - anything more is a waste - anything less is damaging the engine