|The MGA With An Attitude
ALCOHOL IN MOTOR FUEL - FU-112
On 29 June 2009, G T Foster in New York, USA wrote:
"Recently gasoline with 10% alcohol made its appearance at our local gas stations. Are there known issues with the MGA fuel system regarding the alcohol content (fuel pump diaphragm, etc)"?
Early fuel tank sealers are known to NOT be resistant to alcohol fuels. Maybe they have adjusted to the alcohol problem by now (or maybe not). This is serious stuff for some people, but almost amusing for me. I put Moss Motors slushing compound in my fuel tank with first restoration in the late 70's, putting it on the road in the mid 80's. I went through the transition to 10% alcohol fuel in the early 90's. The fuel tank and pump never noticed it, and I wasn't running any filter at the time other then the original screens in pump and carbs.
The trick I think was that I was driving the car a lot at the time, using 500 to 1000 gallons of fuel per year, two or three tanks full per week during the main driving season, and half a tank per week in the off season. I think the tank liner material was simply dissolved and gradually washed out of the tank along with the fuel, and I'm pretty sure the tank was bare inside by end of the 90's. There is no trace of the liner now, as the tank is pristinely clean inside and still in good serviceable condition after 52 years and 375,00 miles.
My personal opinion is that tank liner might be useful for people who expect to leave the car in storage for long periods with half a tank of fuel so it might rust inside. If you would store it for several months, leave the tank full of fuel. If you're thinking about parking it for some years, just don't do it, maybe sell it instead. If you drive it regularly you're probably better off with nothing but fuel inside the tank.
There are some other effects from the 10% alcohol. In 1989 the stuff dissolved the rubber diaphragm in a couple of Walboro fuel pumps, and each time it only took about 30 days when I was driving it regularly. Later on I noticed the Walboro pump was the only one in the J.C. Whitney catalog with a note stating, "Not for use with alcohol fuels". The SU fuel pump diaphragms are laminated fiber (cloth) reinforced (and nearly flat). The only sad stories I hear there are about the diaphragm going stiff after 20 years or so, but not usually leaking.
The alcohol also eats other rubber parts. For many years I was changing grommet seals on the SU H-type carburetor float bowls every year or two as the grommets would deteriorate dramatically and leak. Moss Motors recently offer a different part number for these grommet seals made with Viton, so maybe they will last longer now.
You might expect the alcohol to eat rubber fuel hoses as well. I have been changing the 5/16" bore fuel hoses on my aftermarket fuel pump every five years or so. I've never had a leak there, but they get to looking pretty bad after a while, so I do the preventative maintenance.
The large bore fuel filler connector hose should also be honest "fuel hose". I put a piece of coolant hose in there once, and it was shot in a few years, all soft and puffed up. Moss now has those in the proper material (last time I checked). Real fuel hose will last at least 10 to 12 years in that application, so I change it about as often as my car gets a repaint.
I have been using the two carburetor fuel hoses that are lined with Teflon, and no problem at all with those for 22 years and 225,000 miles on the same parts. That is one lifetime guarantee that is serious and believable. Ditto for the oil pressure gauge flex line hose (but I do keep a spare for that one, just in case).
For the last 100,000 miles I have been running twin Teflon 0-rings in place of each of the carburetor main jet seals with no leaks or sticking. I have installed several sets of these for other people with no problems. Very good conversion bits for cheap. The cork seal for the jet bearing always does well, and cork seals on my fuel tank sender unit have likewise never failed.
The most serious problem I have with 10% alcohol in the fuel is the tendency to boil easier and make the carburetors go unbearably lean in hot weather. Some people have devised various tricky heat shields to keep the carbs cooler, and some may actually help. I have a neat scheme for fuel recirculation to cool the carbs, but I haven't gotten around to trying it yet.
Sometimes you can learn good things by driving a lot.