aviation fuel in 64 fuelie

[Matt L.]

tonight i put 6 gallons of 92 octane and then 6 gallons of aviation fuel from the local airport. i did not see what the octane rating was. my thoughts were that this would wake my car up. especially since we have had 2 good days with great temps and low humidity.
well...it actually started running like it was vapor locking and the engine temp was up from the usual 170 to near 200. i did not adjust the timing. it was still set safe for the 92 octane.i dont have hardened seats in the heads. i have driven this car in 85 degrees with high humidity and havent had these issues. the car has always ran cool. i'm confused. i thought these old cars loved the aviation fuel. especially the fuelie cars.
i appreciate any help and advice.
take care,
matt

[Dan B.]

Re: aviation fuel in 64 fuelie

The AV gas is 100LL thats 100 octane low lead, and yea these old cars do love it. I doubt the AV gas is the problem, I fly piston planes and if there was ever a more perfect time for vapor lock than summer heat in an air cooled engine that has sat for 20 minutes before a restart.......It's the pump gas that is suspect these days, the Aviation fuel has much higher quality (and price). Pilot Dan

[Don H.]

Re: aviation fuel in 64 fuelie

I have run av gas in my '60 fuelie for close to 30 years and it loves it. The FI geru (John D) swears by it. I agree with Matt, the av gas is NOT your problem (unless by some quirk of fate you got some bad). Good luck, Don H.

[Chuck G.]

Re: aviation fuel in 64 fuelie

I've run 100 octane LL AvGas in my 63 fuelie off and on for years. I still do it occasionally. I've never had a problem. I throw some CAM 2 in in occasionally too.

I have found 2 gas stations here in my area of Florida that sell NO ETHANOL fuel. So, I've pretty much switched to the 93 octane no ethanol gas. That makes a HUGE difference.

I have to agree with others.... I think your problem is the ethanol fuel you bought, not the 100 octane LL.

Chuck

[Rich G.]

Re: aviation fuel in 64 fuelie

I have run a mix in both my 68 427/435 and my 66 327/350. Once in a while, the cars run worse like you describe. I know in the case of the 327 it was some crap that got into the carb, because after I got the float chamber cleaned out it runs great. The big block runs great on it after I had the carbs rebuilt, which they needed anyway.

I think the Avgas is a real good solvent and might loosen up the stuff hanging around in the fuel system. Just a guess, but I definitely have seen a few cases over the last ten years which made me scratch my head. It's supposed to run better on Avgas, but once in a while, I had problems. I think every one was dirt related.

Rich

[Matt L.]

Re: aviation fuel in 64 fuelie

maybe it was just a fluke. but it was within half an hour of putting both fuels in that it started acting up. my tank was just about empty so that's why i decided to try it. i do have a new tank but still old lines on the frame rails.
i took it out last night after it got much cooler out and it ran great with no issues. i believe also that i got bad 92 gas. i'll try it again today. it's supposed to be warmer yet today.
thanks for all the replies guys.
take care,
matt

[Richard E.]

Re: aviation fuel in 64 fuelie

My 67/435 seems to run better on Cam 2/110 than av fuel.I have used both in the 435 for over 20 years and the Cam 2/110 seems better.I have better luck using it pure ...

[Joe R.]

Re: aviation fuel in 64 fuelie

tonight i put 6 gallons of 92 octane and then 6 gallons of aviation fuel from the local airport. i did not see what the octane rating was. my thoughts were that this would wake my car up. especially since we have had 2 good days with great temps and low humidity.
well...it actually started running like it was vapor locking and the engine temp was up from the usual 170 to near 200. i did not adjust the timing. it was still set safe for the 92 octane.i dont have hardened seats in the heads. i have driven this car in 85 degrees with high humidity and havent had these issues. the car has always ran cool. i'm confused. i thought these old cars loved the aviation fuel. especially the fuelie cars.
i appreciate any help and advice.
take care,
matt

Matt,

I would suggest doing some searching of the archives on this topic. It has been hashed over many, many times. I think you will find that the consensus is that 99 % of our cars don't need aviation fuel. The main benefits of it as I recall are higher octane and no ethanol. The main disadvantages are that it puts lead deposits on your plugs and sometimes on the body after exiting the exhaust. Did your car detonate before the av gas? Maybe the lack of ethanol would help with percolation / vapor lock issues. Can you get premium gas at the pump without ethanol in your area? You don't need hardened valve seat unless you're towing or running at high RPM for extended amounts of time.

Here's one thread that has some info for you:

https://www.forums.ncrs.org/showthread.php?t=65456&uid=6868

Joe

[Michael W.]

Re: aviation fuel in 64 fuelie

Matt,

I would suggest doing some searching of the archives on this topic. It has been hashed over many, many times. I think you will find that the consensus is that 99 % of our cars don't need aviation fuel. The main benefits of it as I recall are higher octane and no ethanol. The main disadvantages are that it puts lead deposits on your plugs and sometimes on the body after exiting the exhaust. Did your car detonate before the av gas? Maybe the lack of ethanol would help with percolation / vapor lock issues. Can you get premium gas at the pump without ethanol in your area? You don't need hardened valve seat unless you're towing or running at high RPM for extended amounts of time.

Here's one thread that has some info for you:

https://www.forums.ncrs.org/showthread.php?t=65456&uid=6868

Joe

Thanks for saving me from retyping all the above. As stated there's plenty of info in the archives that will help dispel the myths of both Avgas and E10.

It's worth repeating- if a car does not detonate on pump gas, higher octane will not be of any benefit. I've noted that the urban legend of avgas or race gas somehow giving 'more power' has been passed on to the younger generation. I see them lining up at the pumps to fuel up their f*rt can equipped imports but remember that 'that was me' 40 years ago.

[Joe R.]

Re: aviation fuel in 64 fuelie

Thanks for saving me from retyping all the above. As stated there's plenty of info in the archives that will help dispel the myths of both Avgas and E10.

Michael,

You're welcome! As you can see by the link I posted, I asked the same question when I was new here. So, it was easy to find a related thread.

Joe

[Duke W.]

Re: aviation fuel in 64 fuelie

\. i did not see what the octane rating was. matt

When we say "avgas" we mean 100LL (low lead) aviation gasoline, which is avaliable at all general avaiation airports.

However, some light aircraft engines are approved for 87 PON mogas (sans ethanol and the usual automotive additives), which may also be available at some general aviation airports. It is labeled 82UL (82 MON unleaded).

Next time you put something in your car I suggest you know for sure EXACTLY what it is.

The pump should be clearly marked, and 100LL is dyed to give it a blue tint; 82UL is tinted purple.

Duke

[Domenic T.]

Re: aviation fuel in 64 fuelie

If you mix 100LL avgas in a low compression engine you will not see much difference but you will notice it with a high compression engine.

I can't live without it if I want the original performance back in my high compression engines. I can also time the engine the way it was designed to be timed.

Also you get the ADVANTAGE of a little lead in your fuel, not as much as the engine had when it was born but just enough.

I fill one tank with av/gas and the other with pump gas in my aircraft and have switched tanks in level flight and find that on low compression engines such as aircraft engines it doesn't change the power the engine is putting out in flight.

BUT in a high compression engine in a car...... LOOK OUT and hold on.


DOM

[Duke W.]

Re: aviation fuel in 64 fuelie

The octane requirement goes down with altitude due to lower air density, but the fuel has to have enough octane to supply detonation-free take-off power under worst case conditons - sea level on a very hot day.

100LL is about equivalent to 104-105 PON, which is probaby way more than most aircraft engines really need, but aviation standards are very conservative due to the possible dire consequences - like losing the engine just after takeoff.

Most OE Corvette engines will operate detonation-free on current unleaded premiums without having to compromise the spark advance map, but it comes down to each individual case. Also, because of their larger bore, big blocks have somewhat more "octane appetite" than small blocks.

The practical detonation limit on spark ignition engine bore size is about 6", but some big aircraft engines of yore were a little over 6". The larger the bore, the more tendency to detonate at the same CR, boost, and octane level.

Duke

[Larry E.]

Re: aviation fuel in 64 fuelie

Here is my 2 cents worth:

We are all fogetting the other advantage of using 100LL. It will last a lot
longer w/o getting "stale". I only start some of my cars up once/twice a
year as they are stored in "Omni Bags". I have yet to see any of them not start. I usually add a little fresh 100LL to the tank but I'm sure there is some 100LL in there that is 3-4 years old!! It is the only way to go if car
is not used much. IMHO

Larry

[Charles M.]

Re: aviation fuel in 64 fuelie

Here in Florida I find it neccessary to add avgas to my fuelies in the hotter months to avoid perculation and vapor lock.