Av gas experence
Thread Starter
Racer
Joined: Mar 2005
Posts: 253
Likes: 58
Av gas experence
Pulled the old 435 out of hibernation last weekend, tank was empty so
I thought i might treat it to some race gas seeing as it likes to rattle even with fuel boosters.Local speed shop wanted 80.00 plus one tax for a five gallon container.That seemed a little rich so i opted for five gallons of 100LL AV gas.Engine performance was superlative,however it was not long before i smelled AV gas,all three carbs were leaking from practically every gasket. I said to myself,now you are in trouble.Hower i drained out the fuel and sent my honey for a couple gallons of 94 Sunoco, and re tested the car. Every thing was back to normal which pleased me greatly. Found out this week,a female co-worker has a race car and has access to 110 Sunoco race fuel, think I may give that a try.
435er
I thought i might treat it to some race gas seeing as it likes to rattle even with fuel boosters.Local speed shop wanted 80.00 plus one tax for a five gallon container.That seemed a little rich so i opted for five gallons of 100LL AV gas.Engine performance was superlative,however it was not long before i smelled AV gas,all three carbs were leaking from practically every gasket. I said to myself,now you are in trouble.Hower i drained out the fuel and sent my honey for a couple gallons of 94 Sunoco, and re tested the car. Every thing was back to normal which pleased me greatly. Found out this week,a female co-worker has a race car and has access to 110 Sunoco race fuel, think I may give that a try.
435er
Melting Slicks
Joined: Nov 2004
Posts: 2,302
Likes: 26
From: Cave Creek AZ
Originally Posted by 435er
Pulled the old 435 out of hibernation last weekend, tank was empty so
I thought i might treat it to some race gas seeing as it likes to rattle even with fuel boosters.Local speed shop wanted 80.00 plus one tax for a five gallon container.That seemed a little rich so i opted for five gallons of 100LL AV gas.Engine performance was superlative,however it was not long before i smelled AV gas,all three carbs were leaking from practically every gasket. I said to myself,now you are in trouble.Hower i drained out the fuel and sent my honey for a couple gallons of 94 Sunoco, and re tested the car. Every thing was back to normal which pleased me greatly. Found out this week,a female co-worker has a race car and has access to 110 Sunoco race fuel, think I may give that a try.
435er
I thought i might treat it to some race gas seeing as it likes to rattle even with fuel boosters.Local speed shop wanted 80.00 plus one tax for a five gallon container.That seemed a little rich so i opted for five gallons of 100LL AV gas.Engine performance was superlative,however it was not long before i smelled AV gas,all three carbs were leaking from practically every gasket. I said to myself,now you are in trouble.Hower i drained out the fuel and sent my honey for a couple gallons of 94 Sunoco, and re tested the car. Every thing was back to normal which pleased me greatly. Found out this week,a female co-worker has a race car and has access to 110 Sunoco race fuel, think I may give that a try.
435er
. Last week it was $4.99. My car likes it. This is only the 2nd time I treated her. Has a different aroma to the exhaust. No carb leaks.Roy
Melting Slicks
Joined: Sep 2004
Posts: 2,918
Likes: 13
From: NE Illinois IL
Anyone care to speculate why it might cause leakage? I am looking at running it diluted in my car for a few more octane points, but would like to avoid a fire for obvious reasons.
What are others' experiences with AVGAS?
What are others' experiences with AVGAS?
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Michael S. Palmer
Pro
Joined: Aug 2003
Posts: 635
Likes: 1
From: cincinnati oh
love the aroma of that race gas
place in detroit sells racing gas, at dreamcruise every year you can smell the difference in those cars that have it and those cars that dont. personally, i love the smell. it is sweet and aromatic. am i nuts or what, smelling tailpipes. unreal.
Safety Car
Joined: Feb 2006
Posts: 4,142
Likes: 704
You said you pulled your 427 out of hibernation. How long has it been sitting? I think you may be blaming the av gas when dried out gaskets were at fault. The auto trans in my driven once a year car does this. Come out to the garage, big pool of tranny fluid on the ground. Fire it up, put it in gear.....soon the leaks stop. It was rebuilt with cork gaskets, wish I could find some rubber ones.
Advanced
Joined: Jan 2005
Posts: 72
Likes: 0
From: Miller Place New York
I use a mixture of 93 and 101LL AV gas in my BB - about 25% AV gas. It runs and performs well. With side pipes I am not able to hear if it is pinging so I figure a little more octane can't hurt. Not sure if I really need it and a 25% mixture only raises the octane level by a small amout but it makes me feel better when I put it in the tank. Also love the smell, remines me of the good old days. I agree with buns. I don't think it is the AV gas that caused your leaks. The holley on my BB would leak on start up after it sat for the winter months but it would stop leaking after a few minutes. Changed out the gaskets and tried to drive it more during the winter months solved my problem.
Le Mans Master
Joined: Dec 2004
Posts: 5,233
Likes: 419
The reason for the leaks with the Aviation fuel is the specific gravity. Your floats were set up previously for the specific gravity of gasoline which is heavier. The float in the AV fueled carb doesn’t therefore set when the bowl is full. this is what causes the leak. If you used AV fuel without a leak it is because your levels were set to low to begin with.
Just reset your float levels with AV fuel and you’ll be alright.
Just reset your float levels with AV fuel and you’ll be alright.
Burning Brakes
Joined: Dec 2005
Posts: 998
Likes: 2
I tried running 110 octane Cam 2 Racing Fuel in my L76 and it HATED it. Just felt like it was not making the power, lost about 50 rpms at idle. Turns out (from the thread I posted about this experience here) that the higher the octane the slower the burn rate. I wasn't burning all the fuel. After running through that $ 128.00 fill up, and dilluting it every five miles, I was back to normal.
My car seemed to like the "104" octane booster but here people kept posting it leaves a residue on your plugs and entire top end, so I quit using that.
Man I miss the old Sunoco "260"......
My car seemed to like the "104" octane booster but here people kept posting it leaves a residue on your plugs and entire top end, so I quit using that.
Man I miss the old Sunoco "260"......
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
I use 5 gal Avgas 100LL with 15 Gal premium 92 octane.
I can run the timing as far north as 16* and my then 327/365 loved it.
Pure 100% 100LL avgas gave me harder starts and the car was a tad soggier in all spectrums.
50/50 works good to.
I love the smell of burning 100% avgas, everyone behind you for 2 blocks will as well.
Here is a trick.
Go to some hole in the wall airport that has a self serve pump. Drive right up to the pump swipe your card, and fill up. You may have to visit with someone about driving on airport property.
Octane boosters, are junk, and snake oil.
Octane does not make power
BTU's make power
Octane is an anti-knock index.
100LL is about 115/120 octane.
I can run the timing as far north as 16* and my then 327/365 loved it.
Pure 100% 100LL avgas gave me harder starts and the car was a tad soggier in all spectrums.
50/50 works good to.
I love the smell of burning 100% avgas, everyone behind you for 2 blocks will as well.
Here is a trick.
Go to some hole in the wall airport that has a self serve pump. Drive right up to the pump swipe your card, and fill up. You may have to visit with someone about driving on airport property.
Octane boosters, are junk, and snake oil.
Octane does not make power
BTU's make power
Octane is an anti-knock index.
100LL is about 115/120 octane.
Burning Brakes
Joined: Jul 2004
Posts: 825
Likes: 17
From: Rowlett, TX
Originally Posted by buns
The auto trans in my driven once a year car does this. Come out to the garage, big pool of tranny fluid on the ground. Fire it up, put it in gear.....soon the leaks stop. It was rebuilt with cork gaskets, wish I could find some rubber ones.
I talked to a transmission builder friend of mine about this and he explained to me that it is basically the result of an internal leak in the torque converter. The converter normally stays completely full of fluid. When the car sits for long periods of time half of the fluid runs out of the torque converter and back into the oil pan causing it to overfill and then run out the air vent hole. When the car only sits for short periods of time the fluid level in the pan never rises high enough to reach the vent hole so you don't experience an external leak.
