This fall, I wanted some experience with carbs. Being that I switched my Ford 150's bigblock 460's original Motorcraft (Holley) carb for a Rochester Quadrajet, which apparently can't accept the groove, I opted to experiment on my sister's and bro-in-law's 60,000km unit.
I replaced most of the vacuum lines,( as they were all due), blocked off the EGR, up-rooted the air pump, and did a road test with a low pressure pump and 2 gal. tank hooked up, before and after. There seemed to be no difference. They prior mileage was 10 mpg, and the after mileage seemed to be about 10.5 . A proper long trip check did not work out as the electric lift pump was faulty and was leaning out the carb, to the point that my Bro-in-law hooked in another electric pump just before the carb to get him home. I had my suspicions, and had given him the pump and hook-ups just in case. Apparently the two other in-tank pumps are going as well. It is now out of the shop, repaired and waiting.
So, I will continue with this project when the 2 or more feet of snow has disappeared. Now, question: how much do I re-size the jets (15 - 20%) and what do I look for and at for this type of carb re: further work with the groove?
Thanks!!
Luke