and the car ran out of gas while warming up. The good news is I been trying to run it out of gas so I can install a new tank sitting in the shop out there, so the tuning is gonna have to wait.
Sure there isn't a hole in that gas tank? haha. 6 just seems ridiculously low for a sb...I'm around the others, about 19.5hwy(at 75) and 14 mixed running a t5. Hope you can find the issue....wish I could be more help.
and prepped the trunk with POR 15 after bunch of stripping off old paint and crap. I`ll get the tank in tommrow and try and get it timed. Took about 6 hours just to knock this out today, but it looks pretty good.
on my old motor i got 24-26 on the highway and around 15 or so in town, that was with a stock rebuilt 351w 4v with 10.7 compression (maybe a little less with modern composite head gaskets) with a very mild cam, 4 degree advanced cam timing, 600 carter (same as e'brock), performer intake, stock manifolds with 2.25" exhaust, 3.25 gears and 275/50-15 rear tires and that was running the carb inlet pressure at 6psi, if i turned it down to around 4 it would get slightly better but ping like hell around town.
you should have your timing up around 10-12 BTC at idle and around 36 or so all in, you will have to run premium fuel though. if it pings with that combo back it down it down in 2 degree increments until it stops pinging, then bump it 1 degree to see if it's going to ping, if it doesn't ping lock it down there. then check the plugs to see how they look if they are black you need to change the jets and metering rods. you can buy a kit from e'brock and it's easy as pie to change, you just a small torx driver (t10 i think) and remove the covers pull out the metering rod and the hanger, don't lose the spring, and a flat blade screwdriver to remove the jet, easy as it can be
That's why I didn't use the speedo! I Google Mapped the drive, filled up at the beginning, and filled up at the end. Seriously, with a 2.73 rear and a .64 final drive OD, driving 55 on the freeway feels like idling. And the untouched 2v had something to do with it, I'm sure. 91 Premium gas.