hello all... i have finally decided to go to the dark side and do the tbi- carb swap... i have all the stuff i need for now and i have done several searches and it is going as planned i must wait till my mallory adj. fpr gets here on thursday... i am confused about the size of my quadrajunk though??? i bought a book on rochester q jets and it said the only 2 sizes made were 750 and 800 cfm... but others have told me that that made 600 cfm's also.
the carb is from 1976 it came on an automatic 305 i think out of a van. any ideas if it is a 750???

 

pablo honey.... mi casa su casa....
bueller

 

MAYBE I'LL STICK WITH TBI... at least the board was friendly...

 

There are only 2 "sizes", which are about 750 and about 825 CFM. The 825s are quite rare nowadays since they only came on certain early 70s Buick 455s and maybe one or 2 other similar applications at about the same time, so yours is the 750 "size" for sure since it's newer than about 74.

There is a little metal tab on the secondary air valve linkage of most of them that are made for 305s and such, to prevent the air valve from opening too far and creating an even bigger bog than might otherwise occur. This limit to the AV opening limits the total flow to about 625 CFM or so. But the carb is still the same "size". If you want your car to have that strong tendency to bog, you can grind off that tab; and then if you set the tension really loose, it wil lean out so bad that in addition to merely bogging it might even backfire through the carb. Or, if you get your engine to a point where it actually needs that much air (highly unlikely with any 305), you can grind the tab off to let some more in.

Asking the "size" of a Q-jet is simply the wrong question. Since their "size" is all the same, that measurement doesn't apply like it does to a Carter (Edelbrock), or a Holley, or various others.

 

thank you sooo much!!!! that makes total sense to me. i was also just being sarcastic b4 because on the tbi board everyone introduces themselves when someone is new to the board it just seems more friendly...
anyway i will not open up the qjet until i install the 350... i just wanted to get the most out of the engine b4 i got rid of it!!! i must have 20 diffrent articles at home on the computer about tuning tips and stuff like that and i also bought a book on the rochester qjet. it came off an old 305 from 1976 so it should be already set up for my engine i'll just have to do some fine tuning.
i have to use the $13.00 1" spacer for it to fit on my performer rpm manifold and it is open so that might cause a little bog but it could possibly help? we'll see when i get my fpr and start it up! well thanks for the tips and if you have anymoer good info pm me and let me know!!

 

i got my mallory fpr yesterday...!!!! awesome!
its got a boost refrence on it so when i get a super charger or turbo it will help with fuel management!!! everything is almosty back together but 2 of the screws in the adapter kit are too short so i have to now go to the hardware store.