After breaking in my flathead engine, I started to notice odd gas seepage from my Uncle Max-rebuilt Stromberg carbs. The seepage wasn't straight gas, but this gooey, stinky old gas type of seepage. Which was odd because I tried to keep fresh gas in the tank, yet the goo stunk like bad gas. I would fill the tank and top it off with Sunoco 94 octane whenever possible. Gas tank was spotless clean before the first fill up as well. The seepage was coming from the needle/seat bosses and the accelerator pumps holes in the tops. I found a place near me that sells 91 octane non-ethanol gas and the seepage went away within one tankful. I was about to pull the tops off the Stromberg carbs because I thought my floats weren't set correctly. Curious if anyone else has noticed similar type of issues with ethanol gas and any thoughts as to why that was happening?
Probably a combination of the varnishes in the fuel, materials in the seals and gaskets etc. You will probably need to throw a kit in them at some point. I learned a TON in the year or two I was experimenting with E85. The 110 or 115 race gas can do the same thing.
I was reading on here and other carb places that the ethanol likes to creep up the bowl sides and pressurizes the bowl and line up to the fuel pump check valve. The best repair (not always a 100% fix) is to run a fuel filter with a vent line back to the fuel tank OR run non ethanol fuel.
It also boils around 10 degrees less than real fuel. (Or so I was told) Seems like that would also helps increase the pressure in the bowl. I’m running a return line from the pump on one. No leaks on the outside the carb. But evaporates out fast.
Simple answer.......for all the reasons stated above......I run ethanol in my daily driver stuff and non-ethanol in all my older tractors, Jeep, small equipment. My opinion only, I am not a petro engineer......just my choice as an informed consumer.
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