I'm still having problems with my non cc q-jet,i recently had problems with diesel-contaminated fuel,which i thought i had solved until last morning,when my car acted up again(no torque,heavy stumble,erratic idle).

i cleaned the needle and seat and changed my plugs,and it's running better, but now it's smoking like crazy and smells like raw
gas was coming from the exhaust!

do you think i have to rebuild? or is there a specific piece of the carb that i could swap and get away with it?

the reason I'm reluctant to rebuild is because I'm frankly scared of doing so,and is very hard to find someone that knows how to do so,at least in my area.

thanks in advance.
p.s. the reason i asked for your advice is because you are one of the smartest when it comes to carbs.but any help is welcome and appreciated

 

Any evidence of fuel coming out of the carb? Could be your float or needle hung up letting the carb overfill. May want to open it up and have a look.

 

Smartest? I don't think so. I just talk too much.

A rebuild may be in order. Not sure how the diesel would have driven that, other than possibly loosening up crud that gasoline leaves. In that case, you may have problems in your tank as well, in the form of a clogged pick-up sock filter.

A carb rebuild shouldn't intimidate you. If you can be organized, follow instructions, have a clean well-ventilated place to work, then you can do it. In fact, if you've cleaned the needle and seat, you've done half the work required to do a rebuild. I prefer to use air pressure to clean out passages after soaking in carb cleaner, many have reported success using cans of spray carb cleaner with the little nozzle thing to do the same.

If you've gotten all of the diesel out of the system, you could try a can of good carb cleaner gas additive and see if that makes any difference. Changing the fuel filter, perhaps more than once, may be required.

 

I'm not 5-7, so I can't help. But if I were, I might also advise that the gasoline is a little less volatile and a little heavier than gasoline, and will tend to stay near the bottom of the tank. Adding some alcohol (if your regular fuel doesn't already have it) may help "cut" the diesel oil and pass it through the system.

Since 5-7 already mentioned it, I won't tell you how easy it is to rebuild a 4MV as long as you have good instructions. I won't tell you that there are only about eight moving parts within the assembly, not counting the throttles. I won't congratulate you on having the Rochester as opposed to a Carter AFB or ThermoQuad, with more needles and jets than a Columbian airport. I won't advise you that all the key potential problems that happen to the Q-Jet are already well documented in the archives.

Nope - Can't do it...

 

Hey Vader (dont want you to feel left out). I also am getting ready to rebuild Q Jet. What moving parts are there. Also should I upgrade jets while I have it down. I have leaks on it so it needs rebuild. The engine is in serious shape also. I will let someone rebuild that. Rings, bearings, cam ect. But I think I can handle carb rebuild.

 

Float and inlet needle, power piston and its two metering rods, acclerator pump, secondary air valve, secondary hanger and metering rods. O.K. that's ten individual pieces, in five assemblies. Of course, that's not counting little things like check *****, which are moving, of course, and external linkages, cams, springs, and throttle shaft/plate assemblies. For such a simple assembly, it can do an excellent job of metering, power enrichment, and fine idle control if the right components are selected and installed properly.

And it will outflow many other "performance" carburetors with only a little tweaking. Its'potential is frequently overlooked, just because it came stock on so many vehicles.

 

rideon (and srbond), you probably don't need to upgrade "jets". Remember, what controls the q-jet's fuel metering ability is a combination of primary jets, primary rods, secondary rods, and to some extent, the hanger. Do a search, I know I have personally opened some rather extensive threads on q-jet rebuilds. I also have a few articles on q-jet info (once you know how it works, it's a LOT easier to self diagnose, and modify, etc...)

Try reading the .doc files in this directory, on q-jet tuning, etc... also, when you buy a rebuild kit, it has a giant blowup view of the carb, and instructions and the "spec" on what to set your float level at, etc etc....

https://webdisk.ucalgary.ca/~jmknopp/public_html/

 

thanks to everybody for the replies,im still with the problem,but i will try your ideas and see what happens

 

is there a way to check the fuel level,
in the fuel bowl?

 

take off the air horn.

 

It's a fairly simple, yet elegantly so, assembly: