More quadrajet help please! Won’t run

[Ricko1966]

If it starts and runs on fuel down the throat and you no massive vacuum leaks it is carburetor internal,even if the fuel mixture was way off you could still feather the throttle to keep it running. Play with it a little more but I think the carbs going to have to come back off,come apart and everything double checkef.Things like correct gaskets plugged passages etc.

 

[Itali83]

It’s on the bench and I’m going to pull the cover tomorrow to double check. The kit I got from q-jet power was very specific and I had to give them all the numbers from the carb before they would send a kit so I’m thinking that the parts are correct. I appreciate the help and I’ll report back.

Ben.

 

[Paladin]

OH NO... not another Q-Jet not performing perfectly!!! Ohhh... the tragedy of it all! There, as promised previously in another post, my smart ass remark concerning the Amazing Q-Jet!!!! LOL

 

[Ricko1966]

OH NO... not another Q-Jet not performing perfectly!!! Ohhh... the tragedy of it all! There, as promised previously in another post, my smart ass remark concerning the Amazing Q-Jet!!!! LOL

I was waiting and you didn't disappoint me. Thanks

 

[bedwards]

Its the most complicated carb to rebuild I've ever done. But once you get it right its almost as smooth as FI.

more to read, in fact, prob should read this first:
http://www.crankshaftcoalition.com/wiki/How_to_Rebuild_a_Rochester_Quadrajet_4MV_Carburetor

 

[Snoots]

I went the Cliff Ruggles route. Never a problem.

 

[Octane]

Too much operator headspace and unresolved qjet issues go hand in hand.Some of the best performing rebuilt carbs are gm's qjets (not always the best racing application carb tho) that have graced the tables of The Master.

 

[potent rodent]

did u get all your springs back in place and the checkball

 

[Thejoker]

I went the Cliff Ruggles route. Never a problem.

and me.

 

[Itali83]

did u get all your springs back in place and the checkball

for sure got the check ball and spring back in.

I did notice going through my disassembly pictures that there were two springs under the power piston and none behind the inlet filter. I put a new spring behind the filter as the kit came with it but also put two springs under the power piston.

looking at the springs, I’m thinking somehow someone put the filter spring under the power piston along with the correct power piston. I’m fixing that for sure before anything else. I also know for a fact that the main metering rods are seated in the jets and not bent. I took care to make sure they were seated before putting the top lid back on every time. Here’s a picture of the carb where you can see the two springs. Don’t think that right…

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[Zoomalot]

Did the "NEW" kit come with an illustration page?
That will tell you where the springs should go.

 

[Itali83]

Did the "NEW" kit come with an illustration page?
That will tell you where the springs should go.

they had a link to a video which I watched and it only showed one spring. But that carb didn’t have the part throttle mixture adjustment like mine so I kind of just went ahead like it was. Wasn’t until I got to the fuel filter that I found no spring and then started doubting the double spring.

Ben

 

[C10MixMaster]

Hey guys. Really bummed out after spending three hours trying to get my new truck going with no luck.

stock 350 with what appears to be a stock original quadrajet. I bought the truck and was able to hear it fire and run briefly by me pouring gas down the carb. Truck has been sitting 20+ years.

I took carb apart and found full of rust, float literally came apart and secondaries were pretty much seized. I totally took apart, soaked in carb cleaner and got everything like new clean and free.

Got a rebuild kit from quadrajetpower.com and put it all back together. I did drill out the plugs for idle air adjustment. Also punched out plug for part throttle mixture screw as well in hopes of being able to adjust without major disassembly every time.

I bottomed out the idle adjustment screws and backed out 2 turns to make them even and that seemed like a good baseline. Also backed out part throttle mixture screw 3 turns from what I found doing research.

the motor has good compression, good spark, clean plugs and good clean fuel and fuel pump. I can’t get the damn thing to run. It will fire but never catch. I’ve tried manually opening and closing the choke while cranking with little change. Sometimes it fires with choke open. Sometimes it needs choke closed and several pumps of the throttle. I can’t even get it consistent enough to figure out if I’m flooding it or too lean. Any of you guys have a tried and true set up to at least get the thing to run and then tweak from there?

this is my first q-jet. I’m a master diesel mechanic so I’m taking this a bit personal and a bit embarrassed I can’t even get this thing to run. I’m surely missing something simple. I also originally had the float too high and had fuel just pouring out of everywhere after the pump picked up fuel. I took the top off and bent the new float a bit to just eyeball fuel level and at least don’t have fuel overflowing but I know I have enough fuel in the bowl to at least start and run.

any ideas and help would be great.
Thanks!


Ben

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A air fuel ratio gauge is probably the easiest way to take the guess work out of tuning, especially with modern fuels. In addition it will help you tune the APT power valve screw at cruise..

 

[GMFORLIFE]

What ignition system?
Just curious..
If your running points..invest in a reman hei unit..about $75.

 

[ghopp24]

Send it to National Carburetors in Jacksonville FL. They do a perfect job. My 86'quad is like driving fuel injection now.