what gas to use

Hey good info Farna.

There's an old saying: "Lead, follow or get the heck out of the way!"

Since I believe American Motors was a leader in the US automotive industry, I think, we might be able to posses that same spirit to face 'the issues of the day' at this present time.

One of the ways we can lead in the automotive hobby world is to get smart about coping with 'new gas' = E10, aka 'gasohol'.

IMO, if you're not interested in learning all you can about 'new gas', you should be because it's here to stay, as required by US Fed Laws.

*one purpose of lead added to the 'old gas' was for valve cooling: the metal in the fuel provided better heat transfer from the valve to the head when the valves were intermittently closed, but also since lead is a 'soft metal' this provided some 'cushion' to ward off 'scrubbing' there at the valve seats also.

Read Wikipedia article on Charles Kettering: https://en.wikipedia.org/wiki/Charles_F._Kettering

-the evidence (that lead helped to prevent valve seat wear) is obvious valve seat recession as observed by a majority of engine builders rebuilding older engines (this is a well established fact, not my singular opinion)

Lead, added to gasoline, was an octane booster allowing more compression & in the evolution of spark ignition engines compression is a way to increase the amount of power extracted from a unit of fuel ...and this is all about the quest to design and build the most efficient spark ignition engine known to humankind in the world of Physical Science where the Laws of Thermodynamics are king.

(...actually ethanol added to petroleum gasoline was used by some in the early 1900s... but fell out of favor as newer fuel blends emerged having higher octane ratings?)

Some research can be done by studying the US Federal Laws, though they contain more punitive measures, so one has to 'read between the lines' (like 'it will be illegal to put E15 into any car not specifically made/designed for it') -see EPA.gov.com 'rules and regulations for ethanol fuel'

IMO, next one needs to research all the physical materials that are used in automotive fuel systems. = find those charts that compare the chemical resistance of various rubbers and study the chemical resistance of metals (like those used to make carburetor bodies) ...this info is one of the main reasons the automotive industry phased out carburetors in the mid-eighties IMO (but also in that same quest to increase the efficiency level of the spark ignition engine... ~but~ now they 'cheat' because 'add on systems' like fuel injection require an external power source -so the actual increase of the engine's efficiency (that actual thermodynamic efficiency of the engine itself) is nevertheless unchanged (read about Mercedes' new Formula 1 engine that uses high pressure, direct combustion chamber injection... and Mercedes has Ferrari on their heels to lay claim for the highest efficiency rating for an F1 engine... they burn ethanol in F1 racing)

...all the fluids in a car need to circulate on a regular basis; it's not good for an old car to sit parked for long periods of time

-an interesting twist to all the groaning about ethanol in our fuel is to study how Drag racers have been running alcohol fuel for decades and already laid out the dos and don'ts for anyone else to learn about. (eg: they'll talk about their engine oil (dilluted with alcohol) calling it 'mayonnaise' etc)




Edited by amcenthusiast - Apr/30/2018 at 8:26am

Lead lubricates the valve seats.  With sustained high rpm or high valve spring pressure it reduces the likelihood of valve seat wear/valve recession.  You have three choices.  Expect increased wear and relatively early valve jobs, install hardened seats which is expensive and not without risk, or add lead to the fuel you use.  I mix 2 gallons of leaded racing fuel to 6 gallons of premium unleaded.  This gives me a significant increase in octane, allows me to advance the timing for optimum performance, and gives me some peace of mind.  For mild performance cams and valve springs, the folklore is you only need to add lead every third tank or so.  Note that I drag race my car, have performance valve springs, and have a race gas pump just a few miles from home.  

TEL was preferred over Ethanol as a octane booster
simply because you could patent the TEL mix but not
Ethanol.

TEL preventing exhaust valve recession was a by product.

They were well aware that TEL is poison.

TEL prevents excessive exhaust valve recession by preventing
the exchange of metal at high temperatures. Kinda like a spot weld.

I kinda doubt that exhaust valve temps are lowered. If anything
they might be higher.

One added "benefit" of TEL that GM really liked.
The upper cylinder and rings were junk by 100,000 miles.

Planned obsolescence at it's best.

I would be care full with the mid grade gas. not very many people buy it so it sits in the tanks longer which makes it more prone to having water and deposits in it. regular and premium are used more often and there for are "refreshed" with new fuel.

I use cheap mid grade pump gas with no additives in my V8 and low grade in the 6.  When I put them away for the winter, I add Stabil and run it to get it through the system and put them in my heated building. When I get them out, sometimes after 2 or 3 years, they start up and run perfectly. I have been doing this for 40 years and never had a problem. I see no reason to fix my procedure if it is not broken.