I've been doing a lot of research lately, and it still seems to be a toss up if vacuum secondaries give you better gas mileage than a double pumper with mechanical secondaries. My engine is out of a 2000 Tahoe z71- sbc 5.7 350. It is carb'd. Bored .30 over, SRP Pistons, Pink Rods with Arp Bots, AFR heads 195, Comp 1.6 Roller, Comp xp282hr cam, Victor Jr. Intake, 10.1 compression ratio, 230-236 @ .050 lift, 510 intake, 520 exhuast, 110 LSA, 3200 stall, 4.11 Gears, 1 3/4 headers, and a mad dog level 4 trans.
I'm getting around 8mpg with a barry grant 750cfm double pumper racing carb. While it is extremely fun, I spin the tires at anything over half throttle. I bought an edelbrock 1406 600cfm carb with vacuum secondaries to test out. For one, it doesn't start up and stay running as well as it does with the barry grant and I could not spin the tires unless I the pedal was to the floor. However, the gas mileage did seem to be on my side with this carb installed. I don't want to crack open the edelbrock tuning kit I bought if it is going to be a waste of time, because I can return it if it is unopened. If money were not an option, I would try a holley 750 with vacuum secondaries, but I am not made of money, hence my question.
600cfm is probably not enough with this highly modified engine. I have been told double pumpers are not the best for street vehicles since their performance gain is only best known at WOT. On the same note, I was told MPG will not be affected regardless of the carb, but rather how I choose to operate the pedal. Should I shell out the money and try a larger vacuum secondary or am I stuck at this MPG despite what kind of carb I choose to go with? Because if the latter is the case, there would be no reason to switch.
Thanks,
Travis
I'm getting around 8mpg with a barry grant 750cfm double pumper racing carb. While it is extremely fun, I spin the tires at anything over half throttle. I bought an edelbrock 1406 600cfm carb with vacuum secondaries to test out. For one, it doesn't start up and stay running as well as it does with the barry grant and I could not spin the tires unless I the pedal was to the floor. However, the gas mileage did seem to be on my side with this carb installed. I don't want to crack open the edelbrock tuning kit I bought if it is going to be a waste of time, because I can return it if it is unopened. If money were not an option, I would try a holley 750 with vacuum secondaries, but I am not made of money, hence my question.
600cfm is probably not enough with this highly modified engine. I have been told double pumpers are not the best for street vehicles since their performance gain is only best known at WOT. On the same note, I was told MPG will not be affected regardless of the carb, but rather how I choose to operate the pedal. Should I shell out the money and try a larger vacuum secondary or am I stuck at this MPG despite what kind of carb I choose to go with? Because if the latter is the case, there would be no reason to switch.
Thanks,
Travis
