Here and there in the mechanical world, one encounters a hole described in terms of the smooth end of a drill bit just because that's a handy way to approximately measure the interior diameter of something small, using items commonly found around the garage. That doesn't necessarily mean you're literally supposed to drill 'em out -- at least not on a popular carb for which replacement jets are readily available. (That way you'll still have the gasoline jets in a baggie somewhere in case you decide you want to undo this.) Of course, if you can't get replacement jets, that might be what you have to do, preserving as much as possible of any 3-D profile that is evident...
This page has an overview of what *all* one has to do for a properly functioning conversion to E85 or M85 in a vehicle not made for such fuels:
It becomes clear that this is not a one-rainy-Saturday job and that the better you understand the engineering the more satisfied you will be with the results. Cost savings? Depends on what you have to replace and where-how cheaply you can get your E85 or M85. Pollution reduction? Depends on how well you do it. Trivial? No. More like a new techno-hobby.
Note also that you could do it more or less effectively from a technical standpoint and still be illegal, on a vehicle subject to pollution laws.
Best of luck, --Joe
