No Cats on that beast why not buy airplane gas? 100LL. The LL means low lead but it has 5x the lead needed in most small plane engines but Your GM will thrive on it. It’s probably the best for long term storage as well. Most small airports will sell it by the can or at least did. They might even let you drive up to the pumps if you ask them.
I’ve run booze gas exclusively in my 90 Mercruiser V6 4.3 with 2 BBl Mercruiser ( Rochester) since it came out. I’ve likely put 5-600 hrs on it since ethanol came along and it’s now got 1500 total I did change the fuel lines out to be alcohol resistant . Mine sits in a cold barn through all the Northern NewYorkistan winters throughout this period with ethanol gas in the carb bowl as often as not. It’s damp around here like an arctic swamp as I like to refer to it.
My buddy and I tore that carb down 4 years back as the choke plate was stuck fast and it was just time after around 25 years and 1200 hours to put in a kit. No alcohol gas damage or pitting to the carb at all surprisingly. Just the usual dried out gaskets and accelerator’s pump.
The one issue was the rod the choke butterfly . The rod had literally welded itself to the sides at the pivot points. I do mean welded as a gentle vise trip and punches wouldn’t touch the stuff. That was surprising so we just drilled it out and put in a new shaft. I assume it was the fumes rising from what was in the bowl that did it during layup. Anyways back together and it has been as usual since. I was completely surprised to see no signs whatsoever of pitting in the carb body .
So FWIW that’s my Northcountry experience with E10 long term in something roughly similar. Take from it what you will. I’ve seen absolutely no issues with big carbs while my dealings with small engines is totally opposite. Castings pitted, bowls eaten through and I usually replace or tear down at least one a season to magically run fine again. Nowadays if I run booze gas in small engines I put on a shutoff valve in line and use that to shut it off.
I’ve run booze gas exclusively in my 90 Mercruiser V6 4.3 with 2 BBl Mercruiser ( Rochester) since it came out. I’ve likely put 5-600 hrs on it since ethanol came along and it’s now got 1500 total I did change the fuel lines out to be alcohol resistant . Mine sits in a cold barn through all the Northern NewYorkistan winters throughout this period with ethanol gas in the carb bowl as often as not. It’s damp around here like an arctic swamp as I like to refer to it.
My buddy and I tore that carb down 4 years back as the choke plate was stuck fast and it was just time after around 25 years and 1200 hours to put in a kit. No alcohol gas damage or pitting to the carb at all surprisingly. Just the usual dried out gaskets and accelerator’s pump.
The one issue was the rod the choke butterfly . The rod had literally welded itself to the sides at the pivot points. I do mean welded as a gentle vise trip and punches wouldn’t touch the stuff. That was surprising so we just drilled it out and put in a new shaft. I assume it was the fumes rising from what was in the bowl that did it during layup. Anyways back together and it has been as usual since. I was completely surprised to see no signs whatsoever of pitting in the carb body .
So FWIW that’s my Northcountry experience with E10 long term in something roughly similar. Take from it what you will. I’ve seen absolutely no issues with big carbs while my dealings with small engines is totally opposite. Castings pitted, bowls eaten through and I usually replace or tear down at least one a season to magically run fine again. Nowadays if I run booze gas in small engines I put on a shutoff valve in line and use that to shut it off.