Savage_Rob
Serious Thumper Alliance Member
Offline
Mechanically Inclined Amateur
Posts: 6972
Texas (Dallas area)
Gender:
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I've been looking at the differences between a 100% gasoline/petrol ready 38mm Amal Mk2 and a 100% alcohol ready version. Besides the plastic/rubber parts that change, the main, pilot and needle jets all change too. I'm not sure how much the other two are altered byt the main goes from a #320 to a #800. Now, this compares carbs built for a Royal Enfield, but I take it a good guide. Note that the sizing isn't linear between the 300 series and the 800 series either. I believe I have a #330 in mine now but I'm not positive. The Dial-A-Jet installation instructions state that reducing the main jet by 2 to 3 sizes should result in a setup that puts you in the center setting of the dial. I'm wanting to get it so that the installed main puts me at the lean end. That would give me the rest of the range to richen it for running e85.
Regarding the diaphragm, the Amal Mk2 doesn't have one. The only diaphragm in the mix is the one in the petc0ck. For that, I have a used petc0ck already converted so that it doesn't use vacuum any longer. I'll ensure none of the original rubber remains in it and I'll replace the plastic tubes with copper or brass. At this point, one of the parts I still (probably) need to replace is the rubber mounting flange that connects the carb to the cylinder head. Amal has a simple one available but it doesn't bolt up. It's just a short tube. I may need to find/make a metal one and use the alcohol ready tube between. I haven't bought the alcohol conversion kit yet and if I run into too many show-stoppers, I may not.
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