Can i run 100% AVGAS 100LL?

[R413]

Silicone blinker fluid

 

[Michael_]

Tell me again, why do I post on these threads?

Because i have no clue and need advice.

Probably a good idea to mix 1/3rd avgas 100ll and 2/3rd regular gas in a squirt bottle and bottle feed the engine to see how it runs.
If it runs like crap i should probably stay away. Otherwise i should probably fill the whole tank with this mixture.

 

[kiwigtx]

Silicone blinker fluid

Exactly....don't ever use that Dot 5 stuff.

 

[kiwigtx]

Because i have no clue and need advice.

Probably a good idea to mix 1/3rd avgas 100ll and 2/3rd regular gas in a squirt bottle and bottle feed the engine to see how it runs.
If it runs like crap i should probably stay away. Otherwise i should probably fill the whole tank with this mixture.

You will get away with 5 litres to a full tank. That's all you need.

 

[Michael_]

I actually like the idea of running 1/3rd AVGAS 100L and 2/3rd regular gas whenever i can and otherwise running 100% regular gas.
But i probably need to make sure it works before pouring it in the tank because there are so many different opinions out there.

You will get away with 5 litres to a full tank. That's all you need.

That would be easy to do but is this just your opinion or WHY is that all i supposedly need?

At the end i have no idea and need to pick the answer i want to trust/go with.

Difficult decision. I guess i should check my blinker fluid first.
Not that my blinker motor gets seized up while thinking about this avgas 100ll thing.

 

[gkent]

You asked a question and you got mixed advice - as is commonly the case. What this basically tells you is that you should probably just try the **** and see for yourself.

And yes, tweaking the carb(s) does mean more than just playing with the idle mixture screws. If I recall, the issue wasn't so much with jets as it was with float bowl height due to the difference in specific gravity.

 

[R413]

I know this is like a rocket science very difficult concept, so let’s spell it out for you.

When you have 1/2 tank of pump gas in the car (approximately 9 US gallons) put in in 3 US gallons of AV gas. This is 25% Mix. Go drive and see how it runs. It should run fine. If it doesn’t run fine then add some pump gas to this mix until it does run fine.

No gas cans or squirt bottles necessary.

Are your brain cells smoking, that was difficult huh?

 

[cosgig]

There is no need to change anything to run a high octane fuel. I don’t know what AVGAS is, but I run Turbo Blue 110 octane in my 6bbl Roadrunner, almost exclusively. I may get a couple of gallons of non ethanol “rec fuel”, which is 90 octane around here, but it makes no difference in performance. If you’re not racing, and need the exact same fuel every time to baseline your setup, you can run as much or as little as you like, but you have to know why you need it. Octane slows the rate of burn in the combustion process, which creates a hotter, longer burn. A big old cast iron big block needs a slower burning fuel to maximize the burn while in the cylinder, the more octane the slower the burn. Newer, higher revving cars don’t need this, so there’s no use in running it in a small aluminum engine.

 

[Rusty knuckles]

So one guy says run straight av gas No problem. Except you need an electric pump.

another says any mix change requires a jet change Or it’ll run like crap.

Others say use 25%-33% av gas no problem.

the adjustment screws are for the idle feul mixture. wont do anything for cruising AF ratio.

Tell me again, why do I post on these threads?

better get: electric fuel pump, mini starter, mopar performance valve covers, ZDDP, EOS, Rotella, 4 wheel disc brakes, polygraphite bushings, 1.03 torsion bars, sway bars the size of your arm, amber high beam headlamps, amp meter bypass, headlamp relays, 120 amp alternator, Optima battery, pertronix, aluminum radiator with electric fans, green bearings, type F fluid, lobar kickdown cable, subframe connectors, green bearings, 3.55 “posi”, and the biggest BFG TA radials that will fit on the heaviest steel wheels ever made.

PS: don’t ever start the engine unless you remove the coil wire and crank it until you get oil pressure. Saves all the “engine wear” LMFAO

Simply offering the OP my real experience and suggestions to head off any issues and frustrations. Been running this stuff for years in everything from 100 year old tractors designed to run on kerosene, model T's, muscle cars, and lawn mowers. Please share your results. Or be a sanctimonious prick and offer zero experience. Whichever works for ya.

 

[Photon440]

No not straight av gas. If you fill the tank the car will run bad, too lean. The specific gravity is way light compared to pump fuel.

You can add some to each tank as said above, and you don’t need it in every tank so you can take a trip with pump fuel without worries.

like 25% av gas Is plenty.

dont fill the tank with av gas. You will be very upset if you do, anyone that tells you to do it has never done it or was way over jetted and the car ran like crap on pump gas. You have been warned! LOL

Looking at the specific gravity of various racing fuels, it doesn't seem to matter whether they're listed as aviation fuel or race gas, the specific gravity is all in the same ballpark. Chevron supreme 91 is in the .73 range. VP Master Fuel Table | VP Racing Fuels

 

[R413]

Simply offering the OP my real experience and suggestions to head off any issues and frustrations. Been running this stuff for years in everything from 100 year old tractors designed to run on kerosene, model T's, muscle cars, and lawn mowers. Please share your results. Or be a sanctimonious prick and offer zero experience. Whichever works for ya.

Name calling? Ok, whatever, not my game, pay attention!

Read post #3, that tells him what I have done, and what didn’t work. I tried it full strength. It doesn’t work for me. But you and I don’t buy the same batch of fuel, neither does he.

So now read post #19, if you cannot see the ease and value in that post then no help for ya.

sorry my other post are just silliness

 

[Jerry Hall]

I have run 50/50 avgas and 90 octane recreational fuel for years with no ill effects. It's not always 50/50 depending on where I'm at and the availability of avgas. Once my cars are tuned the only difference I see when having to use less avgas is a little less performance. As I only have one car that's considered a race car, this is unimportant. Getting home becomes the major factor. It's not going to quit unless you get water instead of gas.
Another thing I can say is I used Amoco lead free gas in the late 60's and early 70's almost 100% of the time. At the time it was 100-105 octane from the pump. I never had valve problems from these cars with no hardened valve seats. Nobody told me it was something I shouldn't do. I may have been living on the edge, but you can't prove it by me.
Just my 2 cents.

 

[kiwigtx]

That would be easy to do but is this just your opinion or WHY is that all i supposedly need?

I have plenty of experience with that. Much more than 5 litres of 100 octane or AvGas in a full tank of good quality gas is just a waste.

You need enough to lubricate the valve gear, and to eliminate pinging.

I have driven the same type of car as your Charger for probably 35 years now....a '69 Charger 383, a '70 Road Runner 440 and a '70 GTX 440 ..and I didn't have issues doing repairs on them either.

BTW....I used to buy mine from a local aero club also....cheaper than the pump price for Race Gas.

 

[kiwigtx]

Or be a sanctimonious prick and offer zero experience.

There was no need for that. Maybe you are too new around here to know how the guy's sense of humour works.

 

[33 IMP]

I have plenty of experience with that. Much more than 5 litres of 100 octane or AvGas in a full tank of good quality gas is just a waste.

You need enough to lubricate the vale gear, and to eliminate pinging.

I have driven the same type of car as your Charger for probably 35 years now....a '69 Charger 383, a '70 Road Runner 440 and a '70 GTX 440 ..and I didn't have issues doing repairs on them either.

BTW....I used to buy mine from a local aero club also....cheaper than the pump price for Race Gas.

Last batch of avgas I bought (in Arizona) was cheaper than 91 pump (so-called) premium in california. Probably still is. I have a decent stash for my needs, so I haven't bought much avgas lately.
Cheaper than california gas, ain't saying much, is it?

 

[BeepBeepRR]

Tell me again, why do I post on these threads?

better get: electric fuel pump, mini starter, mopar performance valve covers, ZDDP, EOS, Rotella, 4 wheel disc brakes, polygraphite bushings, 1.03 torsion bars, sway bars the size of your arm, amber high beam headlamps, amp meter bypass, headlamp relays, 120 amp alternator, Optima battery, pertronix, aluminum radiator with electric fans, green bearings, type F fluid, lobar kickdown cable, subframe connectors, green bearings, 3.55 “posi”, and the biggest BFG TA radials that will fit on the heaviest steel wheels ever made.

PS: don’t ever start the engine unless you remove the coil wire and crank it until you get oil pressure. Saves all the “engine wear” LMFAO

 

[Dave P]

The local airport where I keep my Cessna has a 100LL pump near the hangers. I've added various amounts to my older cars over the years
with no real noticeable effects. None of these are highly tuned to the last .001 second bracket racers...just drivers. I pretty much fill the tanks at the end of season for winter storage and they seem to run just fine in the spring. Filled up sometimes because I was too lazy to stop at a gas station on the drive home.
Short version...go buy some and try it. It ain't a mission to Mars.

 

[69a100]

Personally, I wouldn't worry about the seats. I asked this same question years ago and was told "you might see some wear after 25,000 miles".

Unless you have a pinging problem or you're racing and continually beating the **** out of it with redline RPM's all the time, just use the pump gas! I just drive my cars so I don't need hi-octane, as I have it tuned where it won't knock on pump gas. All the lead does is protect the seats during hi-RPM operation like racing.
To all the nay-sayers that say otherwise, why do most builders say you don't need hardened seats on a street car?

 

[66Satellite47]

Back in the day, I ran about 50/50 low lead 100 AV gas & the premium of the mid '70's in my drag car, 12.0/CR. The 100 LL will be fine on the valves.

 

[R413]

You don’t have to be racing or wide open to have valve seat wear. The seats gets destroyed just driving down the road. But it takes alot of miles.

A friend had a poly 318 he drove to work daily in big city rush hour traffic. The valve sunk into the seats so bad he couldn’t back off the rocker arms enough to have proper lash. Took about 3 years.

i bought a 62 dodge with a poly that ran bad, guy though the engine was bad. I was checking things and it did run bet very bad. I noticed. O vavletrainclatter from the solid cam. So I adjusted the valves. They were all too tight. the engine ran beautI fully after that. The valves sunk and were not closing. How did the valves sink? The car was a stock 4door daily driver for his daughter in college.