Question for
@sirhrmechanic related to gas. Do you have to do anything special to the gas on the really old engines to get them to run well or anything you're not supposed to do?
So a few things related to gas... and this is for pre-war and early post-war engines. That's WW2 for those who think Post War is The Gulf. Applies to some postwar cars too. Take it for what it is...
Almost all gas today has at least 10 percent ethanol in it. This generally does not have an affect on the running of early engines and cars. The issues come when the engines have rubber or polymer fuel line components that ethanol can attack. SU diaphragm fuel pumps are especially vulnerable... at least the old ones. New production/Repro SU Fuel pumps have diaphragms that are immune to ethanol. Repro pumps are very good, and cheaper than trying to rebuild/tune an old one with new parts. At least cheaper than paying someone. If you can do it yourself, no problem.
Other places to find 'parts' that can be attacked... polymer carb parts, fuel lines, fuel pickups/gauges, etc. Most of this came into use post-war. So not much to worry about pre-war. Muscle cars... good luck! Lots of polymer there.
The bigger issue on older cars is that the fuel tanks almost all have a good coating of varnish and crud that builds up over decades. With 'pure' fuel and no ethanol.... that stuff just sticks happily to the side of the tank and fuel system and is no problem. Add ethanol fuel and you are adding a solvent (like gumout) that dissolves the old varnish into your fuel where it goes into solution... until it gets to the carb, intake and valves. And turns into what is best-described as a "Candy Apple" coating. That gums up everything. 100 percent of the cars I work on get the fuel tank pulled and PROFESSIONALLY (aka not by us!) cleaned, repaired, sealed and lined. We send tanks to a great company in Canada that specializes in this. Guaranteed for life. Applicable to most any car. BTW, for lots of muscle cars and older cars... you can buy reproduction tanks. Beware. Lots of these are terrible! Restoring a heavy sheet metal original tank is often a better option. Last, avoid 'home gas tank sealing kits.' You can't clean up a tank at home well enough to get the coating to stick. Requires industrial level process like dipping and heating. You can't do this at home.
Another issue that is cropping up is the lifespan of fuel. Used to be that gas could last a couple of years in a tank and still run your car fine. Today, a few months and the gas is skunky and nasty. This is because the supply chain today is now so 'efficient' that gas is formulated to go from refinery to 'out the tailpipe' in about 2 weeks. Not sit around. Noone at Big Petro cares about your collector car. They are doing all kinds of things to gasoline to make it cleaner... and work in modern engines. That means the formulations have nothing to do with 'longevity.' So cars that aren't driven can have their gas go bad fast. By way of Anecdote, my M151 Mutt (simple, 1960's design Ford 4 cylinder) was not running worth a damn. Gas had sat over one winter as I had not driven it much. It BARELY ran. Changed gas... ran perfectly. Gas wouldn't even run a lawn mower after. That engine was designed to run on goat piss... But wouldn't run on year old gas.
I had a conversation about gas not long ago with a friend who told me something I haven't confirmed but has made sense... which is that modern gas is made, often, from natural gas, tar sands, other 'base' hydrocarbons, etc. These are 'assembled' into carbon chains that differ from 'rock oil' and are less stable. So they break down much faster. One bit of fallout based on this has been that I recommend to folks to leave their gas tanks almost empty for winter or long term storage. Used to say "Fill it up" to minimize evaporation or oxidation. Now... leave as little gas as possible in the tank and then fill fresh in spring or when driving season returns. Not been doing this long enough to know how much it helps... but it seems good advice. We also use/recommend Stabil but it doesn't seem to help much beyond a few months. But it can't hurt and every bit helps.
Last, the issue of tetra-ethyl Lead. Nasty stuff. But it had its value in preventing valve seat erosion (of non-hardened seats and non-stellited valves) and quite a few engines beginning in the late 1930's through the 1980's were designed to run with 'Lead' Fuel. So a lead additive 'may' be right for your car. That said, for pre-war engines, a lead additive may not be needed at all. And when we are talking about valve seat recession or other 'damage' that no-lead fuel does... we are talking about things that take tens or hundreds of thousands of miles. Running Unleaded in your Model T Ford or your pre-1930 Bentley... who cares? The valves will recede. Unless you are doing 20K miles a year, you will never notice anything in your lifetime. That said, lead additives don't hurt... so if you want to add it... add it.
Last... there are places that sell 'no ethanol' or "Aviation gas" over the counter. I really can't comment on those, because I don't use them. The cars I work on all run fine on base grade unleaded. So that's what I put in them. I would 'expect' that the supply chain for av gas is different from "Minivan gas." And better. But I don't know. The stuff with no ethanol... No clue at all. May be just the same ordinary 'goes skunky' gas with no alcohol in it. I just have no idea. It's expensive so may be it's better? I don't know. Maybe boat owners can chip in. I think a lot of them use it.
One more thing I'll mention is engine oil... because ZDDP (which is a zinc additive) is no longer put in most oils. It is in some diesel oils... Like Rotella... but is phasing out of that. ZDDP is especially critical in FLAT TAPPET engines to provide lubrication between the cam and tappets. Running without a Zinc additive (you can buy them) can kill your flat tappet engine in a hurry. Damage can occur in just 'thousands' of miles. Not tens of thousands. Roller tappet engines are not critical. FLAT TAPPET engines are. Jaguar, RR/B B-Series engines, lots of Detroit Muscle engines, lots of Detroit "Cheap" engines all run flat tappets. The way around this is a zinc additive. Or buy an off-road 'racing' oil like Valvoline VR-1. It is not intended for 'road' cars, but has zinc. I cannot speak for what it will do in modern cars, however (last 10 years-ish?). So beware thinking you should use it in your modern car. I believe it is bad for catalytic converter performance... not engine. And engines now are designed to run without ZDDP. But for older cars, it is critical. Also, for those with pre-war engines... Additives must be used in the specified quantities. In high concentrations, ZDDP attacks yellow metals (bronze, brass, copper alloys) and so 'More is not better.' Lots of early engines have bronze bushings, gears, etc. And with vintage/collector cars... change your oil once a year or every 2K miles. For most, that is a whole driving season plus... Oil is cheap. New engines are not. Just change the oil. If you are feeling wasteful, put the old oil in your lawn mower. But don't leave old oil in your engine for a winter. Change once a year. You'll be glad you did!
That's about the only stuff I can really add. Except to say "New gas sucks" but it beats the alternative... And the alternative is that the greenies and fruitbats are doing their best to get rid of all gas. And it sucks to see nice musclecars having their great-sounding motors replaced with Ghey electric motors and speakers for PotatoPotato sounds.
Hope this helps... any additions, corrections, revisions or input appreciated... we are all learning all the time these days as the fuel companies and gas companies simply don't care about 'old' cars. And forces are doing their best to have them all crushed as carbon creators. BTW, my 1914 Model T paid for its carbon footprint decades ago. 108 years and still going strong. How many cars has it outlasted... each of which had a huge carbon footprint to manufacture, run and destroy? Old cars are the greenest thing on the planet. Old car people were THE original recyclers.
Cheers,
Sirhr