Unleaded gas (56 Buick)

So i find some info about old cars in general running unleaded and i understand the concept about leaded and unleaded. Do i have to use anything in the gas tank every time i fill it up or just run high octane gas 93-94? Its an original 56 322 Nailhead with 30k original miles.

It's not the octane rating, it's the lead or lack thereof. The lead formed a cushion between the valves and the valve seats. Articles have been written stating only high performance engines will wear excessively without the lead. I use a lead substitute every fill up in my 55. Does it do anything? Not sure. Does it make me feel better and Gunk more money? Yup.

Correct, the lead kept the valves from "welding" themselves to the valve seats. Most engine rebuilds these days use either valves or seats that prevent this issue. So, it all depends on when and how the engine was rebuilt, if indeed it was.

I don't believe it's a real issue on low compression engines, but maybe someone else can comment on that....

Your engine was not designed for high octane gas. There os a calculation for that and it is evading me at the moment. I put some Marvel Mystery in the gas every time I fill up and have had no worries.

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Your 56 ( from the factory) does not need leaded gas or lead substitutes. Your 56 may not require high test gas. And you should try it on the regular octane gas to see if it sends signals that it needs a higher octane fuel.

In my case, my 56 with the exact same engine is fed a 91 octane gas without Ethanol ( if one can believe the stickers on the pump). I do pay a premium for this gas. But I feel it's worth it. Before I could get this fuel I used regular octane ethanol blend. The only problem I had was some internal carb corrosion which was discovered when it was rebuilt last year. I am not sure if the ethanol caused one float to develop a hole and sink, which was the reason I had to rebuild the carb to begin with.

I believe using ethanol gas blends is not really a problem if the gas is used relatively quickly, but I do not have any scientific data that backs that up. For example; if I am taking a trip and will use the gas up right away, then I will put the Ethanol blend in. But when I return I usually fill it with the non ethanol gas.

Here is some info that I know is correct. Yes ethanol is a fantastic solvent. Yes ethanol is a corrosive when hydrated so carb floats are good targets. Ethanol attracts atmospheric water like a sponge so longer storage than a month is not advisable so use it right away. Utilizing the true power potential of ethanol requires larger jetting orifices for increased and efficient breathing otherwise stalling and off idle stumbling occurs. When filling up at a name brand station, the only fuel that is really what is advertised, that is has all of that name brand's additives is the premium pump. The regular pumps offers the same fuel as the cut rate station down the street, just fresher. In California we have no choice but to use ethanol. For longer storage we get creative with secret blends. The lead in the fuel actually rendered a cooling effect near the seat and shaft of the valves rather than a true cushioning effect thereby reducing premature metal fatigue and wear.

The Buick and Cadillac block & head castings of this entire 50's and early 60's era had very high nickel content concentrations so setting hard seats into the head is not needed nor advisable since the nailhead design renders the seat very very close to the water jacket and is very easily compromised and a ruined head is the result. Some who actually know what they are doing, freeze the area to be milled and is an elaborate process. But since the high nickel content is there why risk it. These are not tummy button chevy, ford & chrysler engine blocks.

Your engine was not designed for high octane gas. There os a calculation for that and it is evading me at the moment. I put some Marvel Mystery in the gas every time I fill up and have had no worries.

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4 ounces of Marvel Mystery oil to every nineteen gallons of gasoline in mine .

Also, marvel Mystery oil may be why I have NOT experienced vapor lock

Here is some info that I know is correct. Yes ethanol is a fantastic solvent. Yes ethanol is a corrosive when hydrated so carb floats are good targets. Ethanol attracts atmospheric water like a sponge so longer storage than a month is not advisable so use it right away. Utilizing the true power potential of ethanol requires larger jetting orifices for increased and efficient breathing otherwise stalling and off idle stumbling occurs. When filling up at a name brand station, the only fuel that is really what is advertised, that is has all of that name brand's additives is the premium pump. The regular pumps offers the same fuel as the cut rate station down the street, just fresher. In California we have no choice but to use ethanol. For longer storage we get creative with secret blends. The lead in the fuel actually rendered a cooling effect near the seat and shaft of the valves rather than a true cushioning effect thereby reducing premature metal fatigue and wear.

The Buick and Cadillac block & head castings of this entire 50's and early 60's era had very high nickel content concentrations so setting hard seats into the head is not needed nor advisable since the nailhead design renders the seat very very close to the water jacket and is very easily compromised and a ruined head is the result. Some who actually know what they are doing, freeze the area to be milled and is an elaborate process. But since the high nickel content is there why risk it. These are not tummy button chevy, ford & chrysler engine blocks.

Well said

Thanks everyone for the info, Marvel Mystery oil it is!

Welcome Jeff to our forums. That is some decent and useful input. Can you elaborate regarding the recommended 1/4" line thought in detail? Thanks

Great configuration. So that 1/4 extra line goes from the base of the extra ported fuel filter to allow a return path back to the tank while the other port feeds the carb from the mechanical fuel pump. The vapor pressure is drafted back to the tank... Interesting. As we all know fuel injection systems require a closed fuel circuit and an in-tank fuel pump with return line plumbing as well and those no problems with fuel percolation due to the pressure equalization effect gained by the closed system return line.

I run premium gas in all of my Buicks and every two or three tank fills I run a 50% mixture of 100+ Octane Av gas. This works real well.

When I was young many years ago, those people with more assets than me used Amoco in their Buicks and Cadillacs. This was a no-lead gasoline and I never heard of any manufacturer suggesting not to use it. I also do not recall that anyone using Amoco Lead Free having any engine problems.

Joe, BCA 33493