Thread: carbs beat to death yet again

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Hey guys,

I know this has been beat to death but i havn't been able to find an answer to a specific question. This is regarding my 63 chevy truck which is currently equipped with a stock 327 and edelbrock intake. the previous owner put a 750cfm edel carb on it, there is serious stumble when I floor it. My knowledge so far says that is because its too big and the math tells me a 500cfm or 600cfm would work. I'm leaning towards the 500cfm as this truck sees no racing and only the occasional burnout. I'm thinking better gas mileage and really good throttle response. However, the quadra-jet is supposed to get better gas mileage because it has smaller primaries. The only problem though is that they are all 750cfm. So will I get the same stumble I get now when i floor it with a 750cfm quadrajet? Also, will the gas mileage be similar (if i can keep my out of it ) between a 500cfm and a 750cfm quadrajet? Thanks guys! (feel free to throw in anything i havn't thought of.....can't go 2 barrel though...I don't want to neuter my truck )

Well, in theory the Q-Jet with the small primaries and humongous secondaries will get the best mileage. I ran a spreadbore on a 460 in a pickup and got far better fuel mileage then I did with a square bore.....If I kept my leg out of it.... When you get into the secondaries, they don't do well on the mpg at all...but then nothing else does either!!!

Help us to help you more, what rear end ratio are you running and standard or automatic trans, if auto what is converter stall speed ?

Q-Jets are 750 and 800 cfm. A Q-jet only gives the motor what it can take. I have Q-Jet 750 on my 406 sbc and a Q-Jet 750 on my Buick V6

Q-Jet info ---> http://www.florida4x4.com/tech/quadrajet/qjtshoot.pdf

http://www.florida4x4.com/tech/quadrajet

http://www.442.com/oldsfaq/ofcrb.htm


Pat

Hey guys,

Thanks for the responses, I've been too busy to reply the last week. It's an automatic and I have no idea what the stall speed is. I think it's 4.10 in the rear but i'm not sure on that either. (i still have a lot to learn). I plan to go over the iginition system extensively also and I hadn't thought about that, glad you brought it up.

As far as the carb goes I need some better mileage so thanks a ton for the info on the q-jet. That helps alot and I think that carb is ideal for me right now. I can go crazy later but the q-jet sounds like a good compromise between driveability and power.

I think I also need to get some more reading material on this stuff, thanks guys.