Sniper Fuel Economy
Well, I know people have been asking about the fuel economy of carb vs EFI, difficult to relate though it may be, and I wanted to share my experiences.
The rear is an 8.2" w/ Yukon Posi 3.08. The tranny is a TKO-500 with the 3.27 1st gear. The engine is a BluePrint full Roller 383 430hp, coil in cap dist, Edelbrock dual plane EPS, with electric fans. For a carburetor, I was running a Edelbrock 1406 (it's a 1405 set to run leaner from the factory).
Before I moved out to AZ, I used to drive 80/20 highway/city and still have receipts showing 22.9-23.3 mpg per tank on the carb.
Driving from The West Valley in Phoenix, through Phoenix to 87 and then up through the mountains to Flagstaff with the AC on and two kids in the back, we averaged high 18's in the mpg. That includes the 5K ft elevation change and the city driving through Flagstaff.
Once I installed the Sniper system, choose stock cam in the set up Wizard regardless of what your cam is..., I drove it around and let it learn how to be happy. Once it was, I adjusted the Idle AFR to 14.0, The WOT AFT to 13.0 and the Cruise AFR to 15.0. She was happy and had no temp issues of lack of power in Lean Cruise, so I upped the AFR to 15.5. With those settings, I am averaging over 25 mpg. Pure Highway @ 65 is over 27mpg. For my next trick, I'm gonna try and lean her out some more and try to find a stock GM distributor that I can lock out and use the Sniper System to control the timing.
1968, 5 speed, Vintage Air Gen IV, American Auto Wire Update Series, Champion 4 Core Rad, BMR front w/ Koni's, BP Roller 383, Posi 8.2", Solid Frame Bushings