Technical Aviation fuel, should I be using it?

Lick he said

There alot of comparing Apple to Oranges and Bananas !!
Carbs , EFi , Computer controlled, Computer controlled Timing , Low compression, High Compression ,150hp to over 1k hp..
87,89 ,90-94, Blue, Yellow , Green all have there place/use.
Ethanol fuels are hard on normal rubber,, & some Zinc parts .
Good ethanol resistant rubber line 3/8s $7'plus a foot,
LOTHIANDON1940 ( In Md) sounds to me Like same boat /situation i'm in, where I have lived all my life is now considered northern Virginia and all the counties north (emission counties ) do not have No ethanol free on pump but if I go to the south counties that are not considered Northern Va, ethanol free fuel 7 out of 10 gas stations,
The Marine Fuel stable seems to work Longer /better then Red ,
Another thing mentioned in several post was adding high octane fuel Seeing No gain , lost Hp and not adjusting /Tunning for new fuel,,

I miss the $2 a gallon of Blue 7mpg around 2000 drive right up to pump @ air port 2am to go racing

 

...Best to lay that at the feet of all of those little planes flying around over our heads. I'm certain they are dumping 1,000's of times more than little me with an occasional ride in a hot rod.

 

....True that. Those poor souls who worked pumping gas at stations all through the '30's-'70's before unleaded fuel weren't simple minded for no reason. Decades of pumping leaded gas without gloves and breathing the fumes likely led to a huge loss of brain cells....We don't even need to get into those who blew out the brake dust when doing a brake job with compressed air. No worries about asbestos there!!

 

What about a lower temperature thermostat? The carb sitting on a colder engine should mean less heat transferred to the carb. If the metal screws & washers holding the carb on the intake has direct contact with the carb, add fiber washers to limit heat transfer through them.
And perhaps an electric fan wired to run a minute or two after the engine turns off, to ventilate the engine bay right when everything in it is the hottest but cooling air flow stops.

 

I have seen people using wooden close clips on fuel lines up under hood,
1 to as many as 10 ?! ( Old Fix ) never done.
What engine & style vehicle? Not a MG with transplanted V8? Traped heat !!! Pinto Vega.
Is it possible if a V-8 style engine the heat shield under the intake is missing ?
How is the original line ran to carb ?
Do experiment get yourself a gallon of 90'-93'non-ethanol fuel like from a small engine shop Stihl fuel /ext , or maybe 40 50:1 , might defeat the purpose because of the oil,,, So No ethanol fuel,,, disconnect the fuel inlet at the fuel pump hook your gallon
( on ground outside of vehicle ) can up run the car get it to running temperature , hood down ,,,I'm pretty sure it's gonna be hot in your area for the next few days and see what happens ,if you still have the same problem, vapor lock and flooding/boiling,, that way you'll know if it's the quality of fuel the stihl fuel is close to race grade quality..
I think aviation fuel is more stable

 

Help to dissipate heat in the fuel before carburetor , Maybe this , just a thought ,
I have seen as small as 2-1/2 wide
1-1/2 thick & 5 ish inch long ,,, refrigerant store made out of brass / cooper ..

 

Nice... $7.78 by me. The nearest high-octane pump is around $11.

 

It has a worked 355 Chevy in it, close to 10:1. I probably don't need more octane than 93 unless I'm really giving the car some good exercise. It will ping at 91 octane.

 

Gasoline has many components
Gasoline is a mixture of many different hydrogen- and carbon- containing chemicals (hydrocarbons). A typical gasoline mixture contains about 150 different hydrocarbons, including butane, pentane, isopentane and the BTEX compounds (benzene, ethylbenzene, toluene, and xylenes). I believe the main function of BTEX compounds is to raise Octane rating.
Ethanol has an octane rating of 114.

a government site on fuel
https://www.eia.gov/energyexplained/gasoline/octane-in-depth.php#:~:text=Regular (the lowest octane fuel,fuel–generally 91–94)

I’m not sure how too keep gasoline from percolating or boiling, it has a low boiling point, it’s volatile

I think uncle Tony is on to something with fuel percolation
https://youtu.be/-t6geNGbEXM?
si=TTohAnX1uFSn-157
Hopefully this helps
Dan

 

Does it also have domed pistons? My old man has a built LT1 350 that's 10:1 that runs great on 87. Needing 93 is unusual for 10:1 unless your flame path is obstructed in your cylinder or similar issues.

 

I ran 100 LL AV gas in my dirt car 25 years ago. I think it was about 3 bucks a gallon back then. I had no problems with the mild 350 street stock engine I was running. one night when I didn't pick up fuel I thought I would get by with pump gas I detonated 2 pistons. live and learn. Its probably not as good as race fuel that has additives specific for performance engines. the old timers used to tell me AV gas was a dry fuel. I never knew what that meant.

 

The vid shared above to address boiling is essentially a fuel return line. They do work in cars with heavier fuel requirements (hot rods, trucks) and help maintain a solid "head" of fuel at the carb. The boiling after shut down, which was discussed in the reply about the Autolite 4100, can only be addressed by changing the chemical properties, or the content of heavier hydrocarbons. There's more to it but this is the HAMB, not the SAE. How much info do you really need? AV gas in the occasional hot rod? Save your money. Use a quality additive now n then and don't worry about it. Pinging? Back the lead off in your distributor a degree or 2. Some of you may be amazed how little retard is required to eliminate it. Sometimes as little as 1 or 2 degrees is enough. Will you feel it as a loss of performance? I'd bet used fuel pump you'd never know it. In fact it might even run better. Tinker with it, dial it in, make adjustments. Shit man, doing that is ½ the juice of having these old bastards isn't it? It is for me anyways. Carry on...

 

Yep, several years ago we were cruising through the curvy winding roads and hills of southern British Columbia on a 45°C (113°F) day. We filled up in a small town, and my truck was pinging under load. I stopped and retarded the timing a small amount and it went away, then the next day when it was cooler and we fueled up again, put it back to where it was. Retarding the timing when needed isn't a big deal, and for the way most people use their cars they won't notice a difference in power.

 

Live in the Northeast. Been running it for over 20 years. Mix it about 2 gallons to 10 during driving season and a little heavier when cars sit. Never had a gummed up carb or fuel system. Cars start easily after some downtime. Will use it as long as they will let me. Bought 20 gallons yesterday at 5.60 per gallon.

 

We’re about $2.20 a litre or roughly $7.50 a gallon. It’s never been a problem buying and the airport is quite happy to sell you all you want. What they can’t do and won’t do is pump LL100 directly into your car, so gas cans only. A 5 gallon pail of VP C-12 is $200.00 Canadian so the choice is easy to make.

 

If the fuel line sits in a good place there shouldn't really be any heat in the fuel when it reaches the carb. Well, okay, with a block mount pump you'll get some engine heat transfer there, but apart from that the fuel line should be well clear of hot exhausts and such things.
A cooler like that can only cool if the fuel is hotter than the air passing it, in a hot engine bay it may very well become a fuel heater instead. Just like many other times, you need to think things through to get a well working result, just throwing an "upgrade" into the car wherever there's some space may hurt it more than it helps.

 

There IS a work-around!

First, one has to un-learn EVERYTHING one has learned about starting a flooded engine.

Now that the mind is clear, when one attempts to start a carbureted engine that is experiencing hot soak:

(1) Enter the car
(2) DO NOT EVEN LOOK AT THE ACCELERATOR PETAL, AND ABOVE ALL, DON'T TOUCH IT!
(3) Begin cranking the engine
(4) WHILE cranking, after a time (you have to experiment, each engine will be different, but somewhere between 3 to seven seconds), GENTLY press down on the accelerator petal about 1/3 of the distance to the floor. DO NOT PUMP THE PETAL!
(5) The engine will start, but WILL NOT IDLE. Run the engine at a fast idle (1500 RPM?) for about 15~20 seconds.
(6) The hot soak is now cleared and the engine is good to go.

Try it, it costs nothing in parts, and the only labor is clearing the mind!

Jon

 

1000 hp on pump gas wouldn't be HAMB friendly. [ there are turbo forums for that]

Most of those "1000 hp engines" wont be using pump gas while they are actually making 1000 hp. They would have knock sensors that retard the engine and boost control.
Tip the good shit in it............... instant 1000hp


A very good example of this is the Aussie Falcon FG 4.0 Barra which had a multi-fuel engine
It was rated at 195kw on 91 octane fuel [261 hp]
But there was an XR6 spec Falcon FG that was rated at 210kw on 98 octane fuel [281 hp]

The engines were identical in every way [same compression, cams, same engine management] the only difference was the recommended fuel in the owners handbook

So it is very easy to fool yourselves with statistics
Even my O/T factory built 2005 Ford race car recommended 100 octane leaded fuel [for a lowly 450hp] I was told by the factory NOT to use ethanol based fuels in it.
So I sent them the spec sheet for our local Avgas and they replied "run this if you can"

The easiest method is to raise the pressure above vapor pressure [usually about 17psi +] and run a return line.
But the carb will need a deadhead regulator to drop the pressure at the carb.
I've done this in a touring car [race car] with a Bosch EFI pump and a bypass regulator for the return, AND a deadhead regulator for the carb.
The whole fuel line from the tank to the return needs to be above vapor pressure psi

Avgas is easier [but sometimes the almighty rule makers are wiser than us]

 

Kerrynzl sounds good except the carburetor fuel bowls are vented to atmosphere, won’t the gas still percolate after the engine is turned off?I see how the higher pressure in the fuel line will stop vapor lock not a bad idea. I believe gasoline nowadays is geared towards FI, since 90%+ of the cars on the road are FI and might be some of the problem.
Thanks
Dan

 

@carbking how long have people been experiencing flooding due to heat soak, I don’t believe I ever have experienced this phenomenon, oh I’ve flooded engines but usually in the very cold.
Thanks
Dan

 

It does [and stinks] but the electric EFI pump re-fills the bowls and the dead head regulator prevents them flooding.
The EFI pump we used needed a return to recirculate fuel or the life expectancy of the pump is almost zero

The fuel vapor smell is not a flooded engine [the opposite] , the engine should fire on vapors ,but not run.

90% of vapor lock can be cured with a simple electric pump [the above was used in racing in a class that required RON 95 Octane to do our bit to save the planet]

On my 57 I've added a cheap Facet "flow through" pump to prime the engine. These are "Noisy"
The pump is connected to a relay that grounds via the oil sender.

When the engine is running the oil light goes out and switches off the pump and is quiet [it is not a good idea to have pressure on the input side of the mechanical pump]

The noise of the pump soon tells you when the bowl is full [then you crank it over]

 

Still havent learned or can find on the WWW, if some brands or type of gasoline have a higher boiling point than others.
Did the addition of 10% ethanol have something to do with it, and or other stuff that has been done with gasoline formulations to be more enviroment frendly creating the issue?

This didnt really happen years ago.
Personally, I have not had it happen to any of my cars except my Rochester FI car back in the day Guess I'm just lucky.

Still cant grasp why only some cars will boil the fuel in the carb and many dont, when the carb and underhood temps are comparable.
Even cars with comparable type of engine/carb/ manifold setup may have the problem or may not?
Seems to be the luck of the draw.
Makes me think the type and brand of gasoline used may have something to do with it?

I have read that some components in gasoline start to boil at 130-140 degrees. What carburetor isn't at least that?

Bill

 

I know of a few big block NA cars that make 800+ on pump gas with a carb as far as big numbers in Iowa we fill up with e-85. If you don’t think they didn’t have boost in the 20s - 40s you have some serious automotive history to catch up on.

 

It's extremely hard, if not impossible, to find NON ethanol gas in Northern Illinois at the pump. You have to get closer to the Central-Southern part of the state to find anything even remotely good. Fun Fact, though, went to Iowa for a family function in our daily driver and filled up with PURE gasoline and the milage went up considerably! By about 10%... The same 10% that Ethanol reduces the milage by... Go figure!

 

The 4100 carb issue we just had not only boiled the fuel on a heat soak and flood the engine, but also started to boil the fuel/flood the engine while running hot (fuel dripping from boosters and accelerator pump nozzles) and it started idling very poorly, hard to keep running.

Let it cool off and would idle again until hot and boiling fuel in the bowls, with the carb top off, hood open and shop fan blowing at radiator. Fan didn't seem to make any difference blowing or not.


Had a little over 5psi fuel pressure while running, needle and seats were also letting excess fuel by, over filling the bowls when hot and fuel bubbling in the bowls.
Could see it happening with the cover off the carb.

This carb had brass floats and Daytona needle and seats already installed previous.
I am not a huge fan of the Daytona needle and seat and the floats looked to be at a funky angle when seated closed. Could not see anything wrong with the floats other than how they were bent to adjust level previously?

I installed conventional needle and seats and nitrophyl floats that I had. The floats looked more normal at spec. height. That seemed to stop the fuel overcoming the needle and seats and would idle as normal.
Still had boiling during heat soak and dripping from boosters and accelerator pump nozzles.
Ended up lowering fuel level more and it seemed to stop the dripping when the fuel is boiling. It may starve for gas now at WOT, not sure.

Sure, maybe I can try to educate the owner on how to start the car (doubtful)
What to do when its boiling while running?

Bill

 

Isn't it ironic that non ethanol gasoline is only available in farmland.
The farmers that produce the raw materials to make ethanol don't or won't use it in their own equipment because it causes problems.
But we really have no choice.

Bill

 

Had to add a phenolic spacer, in addition to the alloy squeeze plate on the 331 Hemi I installed in '10 vs squeeze plate only on the one I built in the mid-90s. W/o the phenolic spacer it would crap out at stop lights, guessing crappier gas. Not that I have anything that uses E-85, but I saw last week on Power Tour a station had E-85 at the pump like many have diesel. Got to looking at the sticker on it. It said E-85 runs from a min. E-51 to a max of E-83, so E-85 isn't E-85.....

 

AFAIK E85 has 10% less ethanol in winter here in Sweden, to improve cold starting, I'm sure there's some extra wiggle room on those numbers. May surprise people that fuels may change with the season etc, but as E85 is generally meant for modern vehicles that adapt to pure gas, pure E85 or any mix of the two automatically it should not be an issue.

 

We have Winter & Summer blends of gas.

 

I am amazed you have that much trouble finding non-ethanol gas in your area. It is very common here.