delaware39 The reason your engine runs quieter is because you are mixing marvel mystery oil in your gas. The oil is lubricating the upper part of the engine where the motor oil does not reach. Cylinder rings valves etc.

I've been running regular unleaded gas with 10% ethanol since I bought the 39 three years ago. All of the fuel lines, rubber and metal, have been replaced. I also have a modern electric fuel pump. That said, the car runs great and shows no ill effects from the gas. I started adding Marvel Mystery Oil to the gas  a few months ago. It was recommended by a number POC members. I have no idea why it works, but the engine started running quieter and smoother after the second fill-up. You may want to look into it. The engine is a 54, probably the same displacement as yours.

Thank you.

Quote from: Flathead on August 16, 2018, 09:07:10 PM
Thanks for the reply CHS.
I'd rather be running regular but here in Vermont it seems the only non-ethylene gas you can get is super at around $3.40 / gal.  I was wondering if it would do any harm to switch to  ethylene (up t0 10%) regular considering the engine has been rebuilt with modern gaskets.

Gas with 10% Alcohol can damage older hoses used on our collector cars. It can also damage old fuel pump rubber parts. As far as the engine itself it should not be a problem but if the rubber hose connections deteriorate you can have plugged fuel lines. I always paid the extra for the straight gas - even after I replaced all the rubber hose connections and the fuel pump. If you are using your car for a daily driver, it would be best to go through the whole system and find any rubber that will get soft.

Hello, anybody out there?

Thanks for the reply CHS.
I'd rather be running regular but here in Vermont it seems the only non-ethylene gas you can get is super at around $3.40 / gal.  I was wondering if it would do any harm to switch to  ethylene (up t0 10%) regular considering the engine has been rebuilt with modern gaskets.

I use regular non ethanol gas in my 55 Plymouth. No problems. When I used premium gas in the car it had a hard time starting when hot. I swithced to regular and have not had the problem.

I have a rebuilt engine and carburetor in my '51 Cranbrook and have been using non-ethanol super gasoline.  Is this really necessary? I know I don't need the Hi-Octane.
What are you guys putting in your cars?