octane/ethanol question

[JW113]

Hoss, mine is 5:1, makes about 35HP, and runs fine on just about what ever you want to dump in it. Kind of like a Briggs & Stratton. Octane is a non-issue, high or low. And keep in mind that even though leaded gas or "Ethyl" was developed in the 1920s, it was not really in wide use for cars until the late 40s. Most auto and motorcycle engines of the day were low compression and didn't need it, and with the depression and war, nobody could afford it anyway. Detroit started making higher compression engines commonly available after the war. Lead does tend to improve valve and seat live, but need to keep things in perspective. Most people (me, anyway) don't put 20,000 miles a year on ancient iron. So valve/seat life is a not really a concern for most of us.

-JW

[Deye76]

 I use Seafoam in everything. Stabilizies the gas, and helps with carbon build up. In my old Panhead, sometime in the 1980's I had nickel alloy seats and stainless valves installed in the heads. 15% scares me.

[smoserx1]

I read an article long ago that said the problem with old engines and unleaded gas was valve seat recession.  The article said it was mainly exhaust valves in old cars with cast iron heads that did not use seat inserts.  It pretty much said that any head with a seat insert would be ok without lead in the gas.  I was under the impression that most anything with an aluminum head would require a seat insert to last any time at all (but I might be totally off base here) 

[IronButt70]

Friend use to deliver gasoline to several different stations.  Fuel would come in by barge and unloaded into tanks for storage.  He would get a call and take a semi tankard (7200 gallon) load it with gasoline and the ingredients required by the particular station...he said all the gasoline was the same...just different additives to make it what was called for.  He actually added these ingredients. I do not think he was pulling my leg.  Who can know for sure what we get from the pump and the quality.  I have always been skeptical.  Something else to "wonder" ?

I worked for a company in the 70s that did contract work for Mobil. What your friend said is true. All the raw gas comes from a few refineries. Each brand name adds their own additives when it's delivered to their storage facilities.

[JW113]

I read an article long ago that said the problem with old engines and unleaded gas was valve seat recession.   

That is basically correct. The issue is that when the valve and seat get hot, they sort of "weld" themselves together at the contact surface, and when the valve opens, break apart, taking a few atoms of metal with it. Tetraethyl lead helps to slow that process down, acting as an insulator between the valve and seat. Of course, it's also a highly toxic substance and should have never been used in the first place. The real solution is to use materials with a higher resistance to heat. I don't think that just because you have iron or steel seats in an aluminum head mean your motor is immune to errosion, since old Volkswagen heads were also at risk after the switch to no lead. It all depends on what the valves and seats are made of. I think the bottom line is that even with the old stuff, the valve/seat errosion process takes quite a long time until you need to be concerned about it. Basically means shorter time between vavle jobs, say 80,000 miles vs. 100,000 miles. People like to worry about it, but the reality is that it's not the end of the world.

-JW