Q-Jet question M4ME

[T-ROD]

I have a q-jet that was bought completly rebuilt damn near new, its a good carb other than the MPG factor, I know some q-jets if not adjusted rite burn tons of gas, but The one ive got can choke you out on idle at times, and sometimes it gets between 8-9 mpg if you drive without your foot too hard in it, especialy on takeoff, town mpg is about the same, its on my 85 K10, it has a 350, but ive gotten more out of it, but not by much, im thinkin it could use adjusting, its been adjusted before, but it sat and was not run for almost a year, then when it was drove, it felt like TBI, good throttle response, power, and idle, but alot of times it just seems way too rich, ive adjusted to choke, and the barrels are about as clean as clean gets, just wondering what a decent setting is on a q-jet??, ive messed with some of the E4ME ccc q-jets, and considering its already an option, are they better?? I know that the engine needs the proper amount of fuel for efficiency, from driving my buddys firebird you'd compare it to fuel inj. It has 230,000 miles on it with the E4ME and they seem to keep the fuel adjusted very well, Please help with opinions, id greatly appreciate it, thanks!

 

[Jims86]

I have a q-jet that was bought completly rebuilt damn near new, its a good carb other than the MPG factor, I know some q-jets if not adjusted rite burn tons of gas, but The one ive got can choke you out on idle at times, and sometimes it gets between 8-9 mpg if you drive without your foot too hard in it, especialy on takeoff, town mpg is about the same, its on my 85 K10, it has a 350, but ive gotten more out of it, but not by much, im thinkin it could use adjusting, its been adjusted before, but it sat and was not run for almost a year, then when it was drove, it felt like TBI, good throttle response, power, and idle, but alot of times it just seems way too rich, ive adjusted to choke, and the barrels are about as clean as clean gets, just wondering what a decent setting is on a q-jet??, ive messed with some of the E4ME ccc q-jets, and considering its already an option, are they better?? I know that the engine needs the proper amount of fuel for efficiency, from driving my buddys firebird you'd compare it to fuel inj. It has 230,000 miles on it with the E4ME and they seem to keep the fuel adjusted very well, Please help with opinions, id greatly appreciate it, thanks!

To get the most out of a good reman q jet, you need an engine that is in good shape. At least a good compression check should be done.
The CCC q jet is just as good, despite what some may say. The ECM only controls fuel mixture to part throttle operation, then from there on, its just a regular old q jet. The only kicker is tuning timing curves if you wanted to, as the distributor is also ecm controlled.
The only advice I can give you, is to get some books, and learn as much about the Carb as possible, and get a good quality Vac gauge to tune with. 23 mpg has been achieved in 350 powered longbed squares with OD transmissions, 17-19 with 3 speeds. Ther are some spots on it that can leak, even with the passage plugs, and should be epoxied.
if she is choking out on idle, you will want to open her up and make sure the float level is correct, and both the float and needle valve are good. A buddy found a hole in his float, and she smoked bad....like a b-52.

 

[MrMarty51]

Them styrofoam floats can tend to absorb fuel, making them heavier than the norm, they will then sink just a bit and flood the engine at times,especially at lower RPMs.

 

[SlickGTP]

I've found this site to be very helpful.

http://quadrajetparts.com/?osCsid=a8bf120cc4ca96abcf05c8223920828a

..and this book is great. I'm using it to calibrate the Quadrajet on the truck.

How to Rebuild and Modify Rochester Quadrajet Carburetors

 

[T-ROD]

Thanks for The reply, and if theres a way to get 17-19, thats amazing, id be happy with 12-17, even 14 sounds more appropriate than 9mpg, its a short bed 4x4, the engines got a little over 12,000 miles on it, it was also rebuilt, if it matters it has a mild cam, I know it could a little on the vacuum, but its not much bigger than stock, I cant recall the lift though, it used to have a problem with, flooding, I think it was the needle valve though, it was fixed, but Im still wondering why it burns so rich at idle, it starts up great, but when it idles I wouldnt dare light a cigarette behind the exaust, lol, I'll take a look at that link, thanks

 

[Jims86]

Thanks for The reply, and if theres a way to get 17-19, thats amazing, id be happy with 12-17, even 14 sounds more appropriate than 9mpg, its a short bed 4x4, the engines got a little over 12,000 miles on it, it was also rebuilt, if it matters it has a mild cam, I know it could a little on the vacuum, but its not much bigger than stock, I cant recall the lift though, it used to have a problem with, flooding, I think it was the needle valve though, it was fixed, but Im still wondering why it burns so rich at idle, it starts up great, but when it idles I wouldnt dare light a cigarette behind the exaust, lol, I'll take a look at that link, thanks

A good start to re tune is to set the top surface of the throttle blade right to the bottom of the first vac port hole, but you have to look inside the primaries with a light to find the port, then the mixture screws should end up around 2 or so turns out. It is an emulsion idle system, where air is also mixed internally, and it is very important that all passages are clear of debris.

 

[T-ROD]

I'll keep that mind, another question arose when I thought about adjustment, mine has what looks like rectangular shaped adjustement screws, I didnt adjust it last time, but Im thinkin maybe it needed one of those adjustement tools you can buy at about any auto store, do I need that? Ive messed with q-jets but alot have different ways of doing it, anything to take into consideration during adjustment?

 

[Jims86]

I'll keep that mind, another question arose when I thought about adjustment, mine has what looks like rectangular shaped adjustement screws, I didnt adjust it last time, but Im thinkin maybe it needed one of those adjustement tools you can buy at about any auto store, do I need that? Ive messed with q-jets but alot have different ways of doing it, anything to take into consideration during adjustment?

Yup, grab that tool, with a flexible handle.

 

[donut]

Grab that tool. IF it's what I'm thinking of, sounds like your idle mixture adjustment screws.

I'd pop the top, check everything possible. Float level, that the rods are still hanging correctly and not binding, that you don't have a bunch of crud hanging around the bottom of the bowl. Also check the idle screws are adjusted together. Not 1 screw out 1 turn and the other out 5 turns.
My '86 flooded out on me at a stoplight, pulled it apart, found some sort of deposit wedging a rod over and causing it to run massively rich.

Q-jet can be tuned for mileage and performance. I managed to avg 13mpg in my old '73 K-20. Stock size tires, no lift, no OD and 4.10s