If you drive a high performance vehicle that was designed when tetraethyl lead was in every grade of gasoline, how do you compensate now that unleaded fuel is the only type readily available?

Leaded fuel prevented engine 'knock' and cushioned the exhaust valves.

I had a 69 Harley Sportster XLCH that didn't like unleaded gas. I went to the local small plane airport and bought the equivalent of Premium leaded gasoline. The Harley liked it just fine.

This was in the 80s so aviation fuel may be unleaded now. I dunno.....

Normal cure is hardened exhaust seats installed to prevent valve seat recession. I'm building a 440 using K.B. quench dome pistons which will add more turbulence to the mixture on compression for a cleaner burn and more knock resistance.

Hardened exhaust valve seats. Yep.

I've heard tale that a feller needs to beware of av-gas. Something about a higher ash content than standard gasoline. Due diligence would be the order of the day on that.

quote:

Originally posted by lee440:
Normal cure is hardened exhaust seats installed to prevent valve seat recession. I'm building a 440 using K.B. quench dome pistons which will add more turbulence to the mixture on compression for a cleaner burn and more knock resistance.

Yup, that is the permanent solution to the problem.

We don't need it over here so I've seen the ads and know bugger all else about it but how about those bottles of additive I've seen advertised on the net?

I really wonder if all the fuss about lead was much ado about nothing. My nephew has always ran ethanol in his Triumphs without issues, and I've had my 59 Olds running on it for the 15 years I've had it. We run it in our old tractors as well.

The only real problem using leaded av gas is the price per gallon up front ( a little over $4.00 self-serve around here) and the stiff federal fine on the back end.

As long as the timing is set correctly and carbs are jetted for ethanol, its no problem. I know not all carbs get re-jetted but you can increase the orfice and get better horsepower safely. Back when cars had points and condensers the pipeliners woulds tap the distillate from natural gas separators and burn it in their cars.

Same for unleaded in older engines. If you run lean and spark advanced for max hp, you get into the valve seat problems. Like has been said, hardened steel or stellite inserts resolve that issue.

Most people don't remember but Amoco gas never had lead and was advertised accordingly.

To answer your original question, they replaced TEL with less toxic compounds that raise the octane.

The real problem with todays gas is that ethanol crap they put in it. It absorbs water, doesnt mix well, lowers the btu and is generally the worst enemy of an older hi performance, hi compression engine. It turns to gunk even with stabilizer added in just a couple to months of sitting. It's the biggest mistake that no one wants to take the blame for. My car sits with Cam 2 110 octane fuel in it. That's real gas and won't turn in the few months that it sits.

I agree with tiggertate. I have several customers that have old cars that we take care of. They normally don't drive them daily. As long as the carbs are jetted properly and the ignition timing set properly, no problems. The LS6 type motors get octane boosters. The ethanol issue is the worst problem.
Butch

There is a fuel currently marketed which contains no alcohol. It is called 'recreational fuel' and is sold at marinas. It is 90 octane. Unlike Av-gas, the sellers has paid excise tax (formerly known as road use tax) so they can't fine you for burning it on the hiway. Anything with alcohol creates the risk of experiencing 'phase separation' which will cost you megabucks to have the damage remedied. If you are burning it in your classic, I'd strongly recommend you add a stabilizer as the shelf life on all today's fuels is quite short.

Phase separation:

http://epa.gov/OMSWWW/regs/fuels/rfg/waterphs.pdf

Doesn't seem to be a problem.

When I had my 66 GTO w/72 400ci engine I ran octane booster with lead substitute with the lead free gas and it ran like a champ. The more O booster I added the better it ran but it is not a cheap additive so I usually just ran enough to keep it purring.

Baised on advice I recieved from the Deer Tractor dealer, I put Stabil in the gas everytime I put fuel in any small engine. You put 1/2 the amount you would use for long term storage.

Also, in my on the road vehicles, I add 4 oz of Marvel Mystery Oil to every 10 gallons of gasoline I put in the tank.

These measures are supposed to help counteract the negative effects of ethanol gasoline.

As far as a HIGH Performance engine, I would check into Octane Boosters, and consult a good mechanic as well.

A good friend and hunting buddy owns a large small engine shop. He is making a killing because of the latest fuels. He highly recommends Stabil.

Stellite valve seats, harder valves, lower the compression, replace all rubber and leather parts in your fuel system with those compatible with ethanol and you can run 10% E Fuel with no problem

Additives are all BS except for storage.

Or, as was said earlier, go to the airport and buy AV Gas.