What carb should i use for my car

[DoubleV]

Qjets only come in two sizes, 800 and 750. Most are 800. Even the CCC carbs are 800! Just get any basic Qjet from the 70's, have it done by someone who knows what they're doing, and you will be good.

Remember, a 800 CFM Qjet isn't like an 800 CFM Holly or Edelbroke. The Qjet will only feed the engine the CFM it needs UP TO it's rated CFM rating.

 

[jacobdavis1979]

I have another question would it be ok to go with a 750 Q-Jet instead of the 650 Q-jet or will the 750 be to much for what i want.

im runin a 750 q-jet on my malibu it works great but i got the motor to back it up. trust me ive seen dozens of people throw on a bigger carb to their motor hopin it would give them more power. bigger carb isnt always bigger power. if u got a basic motor like nothin big done to it like mild cam stock bore and so on id go with the 650 itl run good with ok milage and plenty of power but if u got lets say a thumper cam like mine and had ur ports in ur heads smoothed out so it breathes better or anything like that id go with 750 cuz u dont want that motor starvin for gas

Thanks for the info the only thing is I bought the car with what it has I don't have the real specs on what lunatics cam it has or what set of rollers it has etc.All I was told was to change my intake cause it has a Victor Jr cause its to much for my car and get rid of the holly carb I have if I what to save gas and get good mileage.So I just wanted to know if its ok for me to use a 750 or 650 instead but thanks for the advice.

In that situation id go with the 650 cuz u will get better milage with it than the 750 cuz ur not pullin as much fuel and if ur vic tr. intake is being usless like some of the guys say it is than u may not have enough motor for a 750 but im not sure

 

[79MaliCrazz]

In that situation id go with the 650 cuz u will get better milage with it than the 750 cuz ur not pullin as much fuel and if ur vic tr. intake is being usless like some of the guys say it is than u may not have enough motor for a 750 but im not sure

Thanks Jacobdavis1979 for the info I will just go with 650 there is a company on EBay that has reman ones for $179 plus $17 shipping and warranty as well.

 

[79MaliCrazz]

Qjets only come in two sizes, 800 and 750. Most are 800. Even the CCC carbs are 800! Just get any basic Qjet from the 70's, have it done by someone who knows what they're doing, and you will be good.

Remember, a 800 CFM Qjet isn't like an 800 CFM Holly or Edelbroke. The Qjet will only feed the engine the CFM it needs UP TO it's rated CFM rating.

From what I've looked up they have 600,650,750 and up they don't only come in 750 and 800.

 

[azmalibuwagon]

From what I've looked up they have 600,650,750 and up they don't only come in 750 and 800.

Just wondering - where do you get these smaller Q-Jets? I've never seen anything other than 750 and 800's. The secondary opening is sometimes restricted (easily changed), but that's pretty much the only thing that I know of that would make you think it's a 600 or 650.

 

[DoubleV]

Guys, there's no such thing as those smaller Qjets you're talking about. They come in 750 and 800 castings. That's it. Anyone who tells you otherwise is wrong.

The only way to have smaller CFM than 750 or 800 is to limit the travel of the secondary air valve ( that's on top of the carb ). The factory did this on some carbs buy simply installing a tang which won't allow the air valve to open all the way. Grind,cut, or bend the tang and the air valve will open all the way.

If you want throttle response and better economy with no loss in power then the Qjet is the carb of choice. This is what they were designed for. You would be mistaken if you think any Edelbrock ( especially a cheap 'rebuilt' or 'reman' one ) is going to match a Qjet. You do realize all the Edelbrock is is the old Carter ( or is that Weber, I forget ) carb from many moons ago that was superceeded by a better carb which just so happens to be....yep, the Rochester Q-jet.

 

[jimmyp618]

Some that come on smaller motors like 305s have a tab on their air valve that limits its travel, thereby "lowering" their CFM "rating". However, grind or bend that tab, and then they're the same "rating" as all the rest.
"CFM rating" is simply the wrong question to ask about a Q-Jet
The best ones were 800+cfm first put into production for buick from 70-72 then pontiac and other started using them after that.

 

[jacobdavis1979]

In that situation id go with the 650 cuz u will get better milage with it than the 750 cuz ur not pullin as much fuel and if ur vic tr. intake is being usless like some of the guys say it is than u may not have enough motor for a 750 but im not sure

Thanks Jacobdavis1979 for the info I will just go with 650 there is a company on EBay that has reman ones for $179 plus $17 shipping and warranty as well.

thats a pretty good price and for a great carb trust me. dont get me wrong edelbrock is a good carb and holleys ok i guess ive had all 3 q jet holley and edelbrock but q jet is the best ive ever had trust me. over time holleys and edelbrock need to be tuned again but a good q jet will keep its fine tuning for the life of the motor believe me u cant go wrong with a good q jet

 

[jacobdavis1979]

Guys, there's no such thing as those smaller Qjets you're talking about. They come in 750 and 800 castings. That's it. Anyone who tells you otherwise is wrong.

The only way to have smaller CFM than 750 or 800 is to limit the travel of the secondary air valve ( that's on top of the carb ). The factory did this on some carbs buy simply installing a tang which won't allow the air valve to open all the way. Grind,cut, or bend the tang and the air valve will open all the way.

If you want throttle response and better economy with no loss in power then the Qjet is the carb of choice. This is what they were designed for. You would be mistaken if you think any Edelbrock ( especially a cheap 'rebuilt' or 'reman' one ) is going to match a Qjet. You do realize all the Edelbrock is is the old Carter ( or is that Weber, I forget ) carb from many moons ago that was superceeded by a better carb which just so happens to be....yep, the Rochester Q-jet.

buddy im not tryin to be mean or say ur wrong but ive seen q jets as small as a 550 and i have a book with the casting numbers that say so. rochesters made q jets sized from 550 to 800. from the factory they only ran the 750 and 800s on big blocks and larger small blocks

 

[jimmyp618]

If it was smaller than a 750 then it was a 2 barrel QJ , 4 barrels were only made in 750-800cfm. If you've seen a smaller 4bbl then I hope you grabbed it cause its the only one in the world. ALL 4BBL QJ carried the same Main body starting on the 750 cfm platform. Sorry if you may have been misinformed about anything smaller.