Just for 1 trip is this worth it

[1974ChevyC10]

ok in the next 2-3 weeks im going to drive my truck to las vegas.it currently has a 600 cfm carter afb.i also have an unknown cfm qjet at my house thats been rebuilt.here is my engine setup.
edelbrock performer intake.
260 duration/440 lift cam-i may not be totally on the money with the correctness of that one but its close to that.
stock hei
1 5/8'' hedman headers.
2 1/2 dual exhausts.
carter afb
double roller timing chain.
what im wondering is would be of benefit to me to swap over the carb just this once since it gets lousy gas mileage with the afb.i dont expect it to get stellar mileage i just want it to get better than the like 9 mpg's it gets.

[87 STEPPER]

What makes you think another carb will get you better MPG than whats on there now???

If you want to swap it do it and see what the truck says about it.

Take the one that on there now with you in case of any troubles you can always swap it back if it gets worse MPG.

[1974ChevyC10]

it was more of a curiousity question than anything.just from what im told cruising qjets from what im told are supposed to get better mileage than a carb like a carter or edelbrock.i drove a truck with a qjet from vegas to phoenix once and while the mileage wasnt stellar it did alright.i guess it has to do with the fact they have smaller primaries but im no expert here.if it wont make a difference ill leave the carter on.

[86swb]

I am no expert on carb questions but have always been told that AFB Carters get better mileage than you could get on the Edelbrock. The Edelbrocks are not known for great fuel mileage. So I would think the Carter would be better. They are both made by the same company but the Edelbrock is made I have been told for performance. As I said "this is what I have been told". Do not know about the qjet. Maby someone else
has a better answer for you. A lot of the cars I drove in the 60's had the Carter AFB on them from factory.

[jermasaurus]

I found a 2mpg increase in mileage with my q-jet over a holley 600cfm with vacuum secondaries (7.5 power valve)

The Holley is better for me to get moving though.
The reason I changed them was for emisions that I failed in June. I gotta go test very soon or there will be trouble.
-Jeremy

[live85]

I also have a 355, towing cam. It has a qjet from a 69 camaro. (no choke or electronics) It all depends on my right foot, but if I get on the Interstate and take it easy I can get 13mpg, while around town taching it up pretty good I get about 9mpg. (85 lwb, no emissions, dual exhaust). I've never run a different carb, so I'm not sure what it would get otherwise.

[Greenlee]

Originally Posted by jermasaurus

I found a 2mpg increase in mileage with my q-jet over a holley 600cfm with vacuum secondaries (7.5 power valve)

The Holley is better for me to get moving though.
The reason I changed them was for emisions that I failed in June. I gotta go test very soon or there will be trouble.
-Jeremy

Same experience I had going from Edelbrock to Q-jet. I went from 12 mpg to 14 mpg. The truck is a 76' longbed with a crate 350. I am no expert, and I have a friend who is a pretty good shade tree mechanic who thought I was crazy for switching. However, in my non-expert opinion the truck runs alot smoother now and it definately gets a little better mileage.