leaded to unleaded

[GN]

I read in AutoRestorer magazine about using aviation gasoline in cars. He said it was ok to do so, just tell the guy that the gas is for your lawnmower. Can not sell for auto use. I am close to a small airport that will sell me gas for my stock 74 318 "lawnmower". My question is, can leaded gas mix with unleaded gas? Is thier anything else that I need to know about?

[ITSA426]

I did it for years and never had problems.  I haven't a clue what avgas costs anymore.  I remember the EAA was pushing hard for auto gas to be used in airplanes because of the price and they didn't have a lot of issues either.

[Cooter]

The reason most "Racing fuels" cannot be sold the average, punk kid in his brand new Mustang GT, is because the lead stops up his cat. Converters. AND, most leaded racing fuels are Supposed to be used for "Off highway Controlled Speed contests"...
Therefore, in order for the gas station not get sued cause little Johnny went and filled up with 110 Octane thinking it actually makes his new car run like his Mopar buddies Badass '69 Charger...you would not believe how many people have stated to me when I tell them that running that high dollar Cam2 fuel doesn't do diddly sh*t for their new COMPUTER controlled car (Designed to run better on 87), they actually tell me that their car runs better....Amazing..the power of the mind...No, putting aviation fuel in your '74 Charger will not give it another 100 HP, but it will allow you to CRANK the timing up, and squeeze that little 318 for everything it's worth...Just don't forget to reset the timing when your done with that Aviation fuel...

[rp23g7]

i drove the gas truck at the Renton airport here in the mid 80s, i would put av gas in my 64 all the time.  Man that 383 ran good, untill i burned a valve.  OOPS. My dad has flown since 1946, he stopped flying when he had a kidney stone, he has to get a full flight physical if he want to fly again, but av gas was over $4 a gallon in 2000.

[Manfred318]

I usually run a mix of Cam2 and 93. Ive never had any problems and the car seems to run abit better. The only place in town that sells Cam2 has it for somewhere around $7.00 a gal. last time I bought some.

[elacruze]

<snip>... the lead stops up his cat. Converters...
<snip>... putting aviation fuel in your '74 Charger will not give it another 100 HP, but it will allow you to CRANK the timing up, and squeeze that little 318 for everything it's worth...Just don't forget to reset the timing when your done with that Aviation fuel...

Just so.

Octane alone makes no power, in fact all else being equal, octane reduces power! Octane is only desirable because it allows mechanical parameters which improve performance. If your mechanicals will run on 87 octane, it's unlikely that 100 octane will make much improvement, certainly not worth the cost.
I did run empirical tests on my '86 Camaro 305 carbureted motor-over 50,000 miles or so I proved that running 93 octane did actually improve my fuel mileage-precisely in relation to the cost. Premium ran noticeably better, but cost no more in the long run so I used it. I did run 100 octane race fuel through once just to see, and got nothing above what the 93 did for me except put a $70 dent in my wallet. YMMV.

I never understood the desire for some people to build motors they call 'streetable' with parameters that demand fuel you can't buy at the pump.

[aussiemuscle]

Not to mention the inconvenience of having to go to the airport to refuel.

[ITSA426]

I've never tried 100LL avgas in the hemi but there are way more airports near me, than places that sell 110 leaded; and the price is probably comparable.  The problem is the hemi get 6.5 miles per gallon.  Higher octane rated fuels (not racing gas) can give more miles per dollar, and they generally extract more heat from the combustion chamber but everybody has to determine what works in their own application.  If I can get by on 87 pump gas then that's what I buy. 

[bakerhillpins]

I was under the impression that running unleaded fuel in engines designed for leaded fuel would burn up the valve seats? And that Octane simply allows you to get higher compression ratios because it retards the tendency of the fuel to ignite on its own at the higher pressures?

What do I know though. 

I seem to recall my friends dad using a lead additive so he could run his 66 back in the 80's on unleaded pump fuel.

[PocketThunder]

I was under the impression that running unleaded fuel in engines designed for leaded fuel would burn up the valve seats? And that Octane simply allows you to get higher compression ratios because it retards the tendency of the fuel to ignite on its own at the higher pressures?

What do I know though. 

I seem to recall my friends dad using a lead additive so he could run his 66 back in the 80's on unleaded pump fuel.

I've been told that you dont need to put hardened seats in your valves to run unleaded gas in a leaded gas engine.