What gas 1954 Vette

Hi Lee,

I have a hunch that your compression ratio might be low-enough to get away with 87 octane. Aside from that, I would be more concerned about the effects of ethanol on your fuel system and carbs. Have you gassed-up any of your cars at Harris Oil on US HWY 441, just south of SR 46, outside of Mt Dora?

They have ethanol-free 87 and 93 octane street gas AND 111, 114 and 117 octane racing fuel. Wonder how the Mosler would run on that stuff!! It's more expensive than regular pump gas, but the gain in fuel mileage helps off-set the cost. Worth considering this due to the extended periods your cars sit in "rotation" in your motor pool.

They are open weekdays from 7:30 to 5:30, Saturdays 8 until noon. Phone is 352-729-3579. Look for a huge yellow billboard on the east-side of 441.

 

As noted, I would be more worried about Ethanol, esp if the car sits for long periods of time.

 

Lee,

The '53 Vette might get away with the 87 octane, the '65 (327 c.i. ?) probably would be happier with the 93. Call Harris on Monday and get their pricing. The increase in fuel mileage could come close in offsetting the higher cost per gallon when compared to E90 and the cost of the Stabil combined.

The trip from Yalaha to 46 & 441 would be fun, using the back roads. Sorry to read about your neighborhood BBQ shop closing-up! It was a landmark, for sure.

 

If the engine is stock you can use 87 AKI. What your friend said is true about the 93 AKI octane. It wasn't available back then. Octane ratings didn't really peak until the late 1960s. From the prewar era until sometime in the 1950s the octane scale used at the pump was MON. It then switched to RON and through federal legislation was switched again to (R+M)/2 or AKI in the early 1970s. So todays 93 octane AKI or (R+M)/2 is the equivalent of 87-88 MON or 97-98 RON. Most of the world uses the RON scale at the pump.

Check out this thread and the article from 1971.
automationgame.com ? View topic - Gasoline though the years

The graphs in this article are in RON which was how gasoline was sold in 1971. To convert to AKI or R+M)/2, subtract 4-5 numbers from RON.
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There are several issues with Ethanol.

The big one to me is that it absorbs water. No biggie in a daily driver, but if it sits for a while, the water will separate from the fuel and corrode aluminum parts.

Rubber parts may be affected by this solvent (alcohol) that was not in common use in the 50's. I would look for brittle fuel lines. It also screws up fiberglass fuel tanks, but I would assume you have a steel tank.

 

I use 91 in my 356 Porsches and VWs. Sure you can use 87, I just think that the 91 burns a little hotter and makes the little engines happy


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I'm not as familiar with 50's vettes as I am with my mid 60's cars, but most of the lines from the tank to the fuel pump and then carb are metal joined at a few select spots by short peices of rubber hose. The hard lines are some sort of chrome plated alloy (my guess) not regular steel.

FWIW for about 10 years i ran ethanol mix 87 in my 66 327 with lead substitute/additive to keep the valve seats cool. Since about 2005 I have run ethanol free 93 exclusively lead sub and have seen no issues over the entire period.

 

You might consider a lead additive or use av gas with lead


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93 is just fine. You could get away with a lower octane but there's no reason to. The cooler burn will just increase the chance of carbon buildup.

The highest available here is 91, and we've had half a dozen GM cars from the 50's. Still have two of them, and they've been doing fine for the past 20 years or so.

I disagree with adding lead additive thinking it's going to save the valve seals. Just a bunch of garbage.

Be sure to start the car every so often, and try to keep the rpm slightly higher the first 15 seconds or so to prevent the plugs from fouling. Some of the older cars don't do it automatically anymore so it's up to you.

 

Lee I believe you can get non ethanol gas in Dade City which may be closer to your location. Search Florida ethanol free gas stations (internet). You will be surprised the number coming back. The ethanol has been hard on my 65 356 fuel pump diaphragm thus I have switched. Compression ratio on the 54 Vette with the powerglide auto was only 8 to 1. Initial hp was 150, later changed to 155 by a cam change. I can't imagine you'd have problems with regular with such a low compression. If it pings then change to 91-93 octane
Docf

 

Lee the 53/54 Corvette has a special place for me as it started my passion for cars in general. At 9 yrs old remember it's unveiling in Popular Mechanics and Science. To me the thought of going to heaven was St. Louis the birthplace of the Vette. My first a 58 with 94 thousand miles on the odometer followed by 63 split 340, 66 427, 70 350-350, then disenchanted with the 73 350 never another and off to other varied marks.

 

The idea that octane rating affects combustion chamber temps (under normal conditions) is incorrect. Higher octane merely resists detonation compared to lower octane fuel; it doesn't burn any "hotter."

 

The lead is not for the seals, it's for the valve seats.

 

That's what I meant...my brain does fart sometimes.

Lead substitute has been regarded as useless for a long time now. I don't even know of anyone who still uses it.

 

Always had the impression that higher octane burned at a higher temperature, helping to resist carbon buildup and also prevent detonation by not igniting before the piston is at its highest point?

I could be wrong in theory though. I'm a collector, not a builder

 

On my 59 Corvette I put stainless steel seats in it in 1981 when I rebuilt the 283. I've seen tons of heads with recessed valves over the years so I'll play it safe and still do the extra step. I suppose there are lots of theories and a lot of it is based on expected miles.

 

Higher octane slows the flame propagation, and resists preignition. It's not temperature related.

 

With an 8/1 ratio the engine would most likely run fine on 82 octane. 8/1 is an extremely low compression ratio.