Quadrajet flooding and more

[vdb11]

Hey all,

Long story short I put a fresh(er) 350 in my 71 K10, which had a Qjet on it. My old motor had an edelbrock. I want to put the Qjet on but I have run into some problems.

I just rebuilt the carb. Previous to this the carb hadn't been run in over a year. However it will not start/stay running. It appears to be flooding from the very start. It does take some pumping to get it to fire, but the accel pump is pushing fuel into the primaries.

The truck will start with some pumping and then quickly stall. It seems to be flooding because it will blow gas and/or flames from the top of the carb. If I keep my foot into it, it will stay running for maybe 5 seconds then flood out.

The only thing that I messed up when putting it all back together was I made the dumb mistake of drilling out the secondary shaft too large to put the pin back in so the secondary choke lock does not work, but that shouldn't have any bearing on this.

Everywhere I looked said its the float/needle. The seat and needle are new. The float is the old one (I have a new one). When I took the top back off the carb the float was "floating" and not sunk, it was light when I assembled it so I don't "think" its leaking, but I could be wrong.

Any other ideas? I think the timing is pretty close, the Edelbrock ran on it before. Also it has a mechanical fuel pump (stock). The engine and carb are from a 77.

Some things I plan to check next time I have time:
1-Make sure the float hinge pin is pressing up against the top of the carb and holding the float still
2-Try the new float I have.

Any other thoughts or things I should check?

Also, how does the choke work? The secondary choke is sprung shut, but the way mine is set up now, the primary choke is just kinda loose. It has the stock vac choke. Is there supposed to be a pull spring anywhere to hold it closed?

Thanks all!

[Longhorn 70]

QJets leak from several places. There are gaskets, needle and seat, welch plugs at the bottom of a couple of bores... I'd double check float. If it is a brass one, it could be filling with gas. If it is the black bakelite one, it could be old and be getting porous. See if you can spot the leak. If you have an electronic pump, run pressure to it and see if you can find dribbles.

Good luck with this one.

[zeldman]

Gas and/or flames blowing out the top tells me timing is off. Also if you have to keep your foot into it to run 5 seconds tells me timing. Or possibly firing order is crossed up. Wear safety glasses while working on it or its poof.. no eye brows. Dont ask me how I know.

[geezer#99]

Likely you have the needle hung on the float wrong.
Here's a link to explain it plus some good info.
Take a pic of your carb from 3 sides and we can better help cure your choke problem.
http://www.crankshaftcoalition.com/w...#Trouble_spots

[BIG69GMC]

Hey there, i 2nd Geezer, i had a similar issue where i got a sliver of metal that jammed the float port at wide open and was causing it to dribble and shoot fuel out. It would start and only want to run at high RPM's

Hey Geezer, thanks for that website, some good info on there. I saw i could definately improve my throttle spring to a better location.

[Longhorn 70]

Let me back up here....Did it ever run right since you put the new engine in? Did it run OK and then when you rebuilt it, it started having the issues you described?

[vdb11]

Thanks for the responses guys!

Longhorn, the engine has run a short time since I put it in. It ran and started perfectly fine with the Edelbrock on it. The Qjet carb was only tried on this motor out of the truck sitting on blocks before it was rebuilt. The engine would not fire, and so I put the Edelbrock on to get it running and figured I would rebuild the Qjet in the meantime (it was all plugged up from sitting anyway).

That's the reason I wasn't thinking it was timing. With the edelbrock it would fire right up. I set the timing (crudely) before the engine was put in. It would idle just fine, maybe just a touch of hunting but hardly noticeable. Are the qjets more sensitive to timing?

I drove the truck four miles with the Edelbrock and new engine and stopped to check things out. Both exhaust manifolds were red, and the pass. side was cherry red where the runners came together. So somehow something got messed up in the Edelbrock to cause it to start loading during the swap. I also had the plug wires touching the manifolds so they had burnt through and were arcing (that has been fixed now). While I could just fix the Edelbrock, I don't really like the Edelbrock and would prefer the qjet, hence why I am just trying to fix the qjet.

I will check out the site geezer thanks! I was watching some videos as I was doing it but I surely could have messed it up. I will try to get some pictures of the choke tomorrow.

EDIT: Ah Ha! I looked at the crankshaft website and sure enough, I do have the needle clip hung on the float wrong! I have it hooked through one of the two holes. Geezer is right on! Unfortunately I will not be home until tomorrow to try this out. I will be amazed if something so simple fixes this problem..

[Longhorn 70]

great news... When you do this, inspect the float. If you are going to have it apart, you may want to install a new float at the same time.

[geezer#99]

9 out of 10 of the videos on youtube hang the needle on wrong!

[vdb11]

I was thinking the same thing Longhorn. While the old one felt very light and was floating well when I pulled the top back off, I still may put the new one in anyway while I am in there. The biggest thing I was worried about was not having the right float. The one I bought is a nitrophyl that weighs 6.5 grams.

EDIT: Ha geezer I never knew that! Very interesting!

[zeldman]

Based on your descripption, cherry red exhaust..... slow timing. Or air pockets in the water in the cooling system. Or very, very, very lean condition. Quadrajets are great when running right, and just plain bad when a little off.

[vdb11]

really? I was told by someone that my cherry red exhaust was from the carb loading and that it didn't have anything to do with timing. I don't know enough about these old carbed engines to know. When the engine was still out I set the timing crudely by pulling plug 1 and setting it at TDC and marking the distributor base and cap. I had it set at roughly 10 advanced. I figured that would be good enough to start and run, which it was with the edelbrock. I figured I could dial it in once it was running in the truck.

When I first saw the red exhaust I thought it was timing myself until some passerby told me it was the carb (said he had worked on them before but who knows).

[vdb11]

Well she runs!

After redoing the screws in the in the throttle shafts and putting it back together, remembering to hang the needle right I got it to fire and stay running!

She is hunting a little bit at idle right now, and I didn't get a chance to drive it yet.

I will eventually need to find a different throttle plate for this carb as the fix i have on it now is not very permanent. I ended up breaking a tap in the secondary shaft and reaming out the holes for the secondary shaft to go into slightly.

I will have to get some pictures for you guys of the choke so I can tackle that next.

[geezer#99]

Did you lock-tite the screws into the throttle shafts or peen them into place?
You don't want one coming out and into your piston's.
THe hunting could be lack of timing and/or mixture adjustment.

[vdb11]

I put blue loctite on the screws and I peened them. I had to drill and tap all of them to 6-32, except two of them because my tap broke. Two are drilled out and 6-32 screws with nuts. I know this is not ideal, I would like to find another carb bottom or at least new shafts. The two with nuts also have loctite and I peened them. They are on one of the secondaries so luckily not restricting airflow too badly.