I switched my 12.5 comp 377 to E85 a year ago and it works great.I was told that the limit is 13.1 comp with pump E85.The E85 i have been buying here in Arizona has been testing at 90%.
I purchased a kit from quick fuel tech. in Bowling green Ky. It had metering blocks 130 needles and seats,air bleeds,and brass floats.also the squirters need to go up about 4 sizes or so.I also use Comp cams Max jets that are numbered by the sized in thousands.
The rest of the fuel system needs to be alky compatible.
The car picked up 3 10ths and 3mph so far and seems to be more consistant and run cooler. The car was on the Tucson pinks all out.
The guys at Quick fuel can help you with any tuning questions or parts you need.
Chevyhighperformance.com has a article on there web site from the Aug 08 issue about changing a carb to E85.
I hope this helps with any questions.My e-mail is
[email protected] i can answer any questions or point you in the right direction.I hope this helps.