Posted by Chris Case [75.36.33.240] on Tuesday, May 07, 2013 at 19:18:40 :
In Reply to: Re: My home made diaphragm is 3 years old. posted by Kaegi [24.16.253.154] on Tuesday, May 07, 2013 at 18:25:13 :
I haven't messed with the bigger one, so I'd need a pattern.
Buna is old, WWII era, man made rubber. Black. NOT Neoprene, which is good for oil, but NOT for gas. Cheap ol'Buna is listed in materials charts as good for gasoline and also ethanol. My 3 year life span means it's good for gasohol too.
At least I tell you what is in my "approved for modern fuels" diaphragm. Manufacturers make claims about their special anonymous material, but I bet it also is cheap ol Buna.
But I think the major prob with gasohol is it's corrosiveness to metals. Rubbers were always the weak point, even in the days of leaded fuel. Ask any old mechanic how I know... ;^) The first flat heads I bought in circa '75 came with several pumps under the seat, it wasn't an ethanol problem.