Brodhead Pietenpol Association

Original Posted By: owner-pietenpol-list-server(at)matronics.com
WaltThe auto gas problem in the USA may be different than here in Canada buthere goes: The 80/87 is the octane rating. Octane is a measurement of therate at which the fuel burns. 100 or 110LL are higher in number and actuallyburn slower, therefore less prone to detonation knocking. The Av gasoline'sstill contain tetraethyl lead as an additive to slow combustion and as aside benefit the lead coats the valves with lead oxide. The oxide preventsthe valves from sticking to the seats and tearing microscopic molecules ofmetal away from the seats as the engine runs. The lead oxide is what givesexhaust stacks of aircraft that light gray colour. It is also poisoning ourbrain cells....!!!??? Too much lead as in 110LL tends to build up on theplugs of low compression ratio engines such as our beloved A65. Aggressiveleaning will keep the plug hotter reducing the problem a bit.Auto gas is not controlled as closely, as to exact content of the blend, andtends to be more volatile than av gas. This can lead to vapour lock which iswhy the fed man gets so upset about us using it. The auto gas does also havea tendency to harm the rubber parts in older systems. The easy fix on noncertified machines is a change to neoprene.One more point. Av gas does not go "sour" as quickly as auto gas. If you areputting your aircraft, using auto gas, in storage. Drain the auto gas andrun it up, and out, of fuel on avgas. This will prevent gummy deposits fromforming in your fuel system.The other alternative is to add a fuel stabilizer.Back to the valve seat issue: If you decide to run a lot of auto gas throughyour engine, check for valve seat wear. They can wear out fast enough to useup all your lifter travel. When the valve operates with no clearance weardrastically increases.Bottom line for me is I prefer to take the lead fouling and higher price ofAV gas for the peace of mind rather than the carb gumming, vapour lock(unlikely at our altitudes) and system incompatibility of the auto gas.Fly safe!JohnP.S. Congrats on completing your Piet Walt. Wish I wasn't so busy and couldmake the same progress on mine.-----Original Message-----

Original Posted By: "Carl Loar"
Figured when I got away from 2 strokes, I'd get away from all the fuel problems.Now that I'm ready to fly my new project with an A-65, I hear " auto fuelmelts your rubber parts, gaskets and needles, 100 oct has too much lead, 100LLhas less but still too much." There are additives for this and that. The old days when I just mixed some oil with gas, now doesn't seem so bad.Why is the new auto fuel bad for the A-65, but my new van is past 100,000mi withouta tuneup???What IS the poop on this??waltNX140DL(north N.J.)________________________________________________________________________________

Original Posted By: "walter evans"
Walt, the alcohol in the auto gas is what messes up the rubber stuff. Forwhat it's worth, citco ( at most locations)is alcohol free. The only other place with alc free fuel is meijers stores.You gotta check on the pumps, if it has alc,it has to say. Most of the guys I know that have A65s use 80 avfuel. Maybesome of the older grass strips in your area may carry it.Carl----- Original Message -----

Original Posted By: Kip & Beth Gardner

Original Posted By: "Kip & Beth Gardner"
You can go to http://www.eaa1067.org/images/jig.jpg and see a picture of oneI made. You put the drill in from the right and place the bolt in the holein the metal fitting on the left. When making the jig you drill out theleft hole with the drill coming from the right. That makes the drill comeout exactly where the hole is on the left. It pushes the bolt out of theway and you have a straight hole drilled from a hole in the fitting on oneside to the hole in the fitting on the other. Hope this helps.Ted BrousseauYou could also got to http://www.eaa1067.org/thomasville_fly.htm and seesome pics of the First Annual Intergalactic Pietenpol Association meetingheld recently at the Thomasville GA fly-in. Did I spell that correctly Don?One of the pics at the bottom of the page is the drill jig.----- Original Message -----

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Hi Walt,Hopefully Chris Bobka will weigh in on this one, but I'll give my two centsworth.The other respondents are correct - it is primarily the alcohol in autogasthat causes the problem. Whether or not you will have a problem depends onthe components in your fuel system - it shouldn't hurt the engine itself(the A65 was designed to run on 73 Octane, and in the late 30's when it wasdesigned, avgas hadn't been invented yet). The usual problem is the needlevalve in the carburetor. The original design used a neoprene tip that madea nice effective seal against the brass valve seat. However, the neoprenetip is attacked by alcohol and tends to swell and distort, and eventuallypartially dissolve. I had a J-3 Cub with an A-65 back in the late 70's andearly 80's and ran autogas in it for about a year and then noticed theengine running way too rich, with a definite loss in power. I investigatedthe problem and found the needle valve in very bad shape. I replaced it(with another neoprene tipped valve) and switched to 100LL (80/87 wasn'tavailable in that area) and the problem went away.Now new needle valves are available made from stainless steel, with noneoprene tip. I put one in my Pietenpol when I overhauled the carburetor,but when I tested it to set float level I found that it leaked like a sieve.Stainless steel just doesn't seal well against brass. I eventually lappedin the needle valve by smearing Crest toothpaste (which has a mild abrasivein it) on the needle, chucking it in my drill press and spinning it fairlyslowly while I pressed the brass seat hard against the sealing surface. Thetoothpaste did an excellent job as a lapping compound and when I reinstalledthe valve and seat in the carb it didn't leak a drop. I still intend to run100LL in the Piet - just put the stainless needle valve in just in case I'mstuck somewhere and have to use car gas.Some gascolators and selector valves also use neoprene seals and can be madeleaky by using autogas.Incidentally, while I've heard of the use of 100LL causing lead deposits onthe spark plugs, I never saw it on that J-3, nor on the Cessna 140 (C85Continental) that I owned up until this past April.Your mileage may vary.Jack -----Original Message-----

Original Posted By: clif