Freshly rebuilt quadrajet flooding from top of carb

[gregcarter]

Thanks, I'll order them on Monday.
I suspect that since you didn't say that I should change anything else that I will not be changing any of the other components.
I also didn't mention that I'm looking for economy, so hopefully this setup will be adequate.
In many of the pictures in the book, I noticed a dam between the accelerator pump and the fuel bowl.
My unit does not seem to have one, it is just a big void. Is this common?
Thanks, G. Carter

[Cliff Ruggles]

If you are having issues right after a "rebuild" I would install one of our kits as well.  Then you will address all the components related to flooding, and get parts in there that will hold up in this new fuel......Cliff

[gregcarter]

ok, I received the main air bleeds.
They appear to have a .126  od.
What size should the holes they fit into be?
The upper ones look fine, it's the lower ones that may be too small.
Thanks,
G. Carter

[Cliff Ruggles]

They fit the airhorn and main casting on all models that used 4 main airbleeds.....Cliff

[gregcarter]

Ok, I finally got this one back together, filled the floatbowl on the bench, installed it the truck, started right up, but I had to hold the choke almost closed to keep it going.
I let it warm up like this, thinking it would get better, opened the idle mixture screws out, thinking it would get better, raised the idle speed up, backed out the mixture screws some more, but it still ran lean, lean lean.
I closed the choke plate almost all the way, and the idle came way up, and smooth.
I shut it off to ponder the problem.

The original problem was stalling at stop signs, and a super lean idle. (not flooding after a rebuild, as this thread heading implies)

In the carb reconstruction, the idle tubes were replaced to .035.

The float was replaced and raised to .025, it had been at 7/16ths.

The power piston was stuck up with about 1/8th inch travel from a bunch of gummy stuff down around the adjustment screw.
This model PP (Edelbrock 1902) has a horizontal adjusting screw between the mixture screws.
When I set it up I turned the screw in until it just barely lifted the PP as a starting point, as I had no information on where to set it.
I suppose I could try raising it a little, to see if more fuel will get to the idle system, but I thought I read somewhere that jets and rods had nothing to do with the idle system.

The idle shaft was bushed.

The upper mabs were decreased to.042 from .052.

The lower mabs were increased to .042 from .110.

The carb body was dewarped, and the airhorn was sanded flatter than it was.

The body was filled with carb cleaner for 20 minutes, rinsed with water, blown out with air, then spray carb cleaner, and then air again.   

So that's where I'm at.

I thought I would take a vacuum reading tomorrow, but I don't know what it should be for this setup.
I thought I would test for manifold leaks again to see if I missed any.
I also thought that perhaps the idle downtubes may not have been cleaned adequately as the carb cleaner never got in there, even though I sprayed and blew them out several times.

I appreciate the help and recommendations you've given me so far, and I'm looking forward to your response.
G. Carter

[Cliff Ruggles]

That small cam in a 350 engine should produce good vacuum at idle and not need a lot of idle fuel from the carburetor.  The specs listed look fine, if it doesn't work well it has a fundamental issue someplace. 

I see this sort of thing quite a bit, as about 1/3rd of what we do here these days is working on carburetors that have just been rebuilt but don't work correctly......Cliff

[gregcarter]

You're right, it has plenty of vacuum.

I removed the carb, made a plate with an air chuck to seal the top of the manifold.
I put about 20 psi in there and couldn't hear any leaks around the manifold with my stethoscope.
I made a smoker and dumped smoke into the manifold until a little drift came out a open valve cover.
I don't think its leaking anywhere.

The last time I had it running, I sealed off every hose fitting (vacuum source) from the carb, ran it at idle, it was very rough.
I closed the choke to get it to smooth out. Then I opened and closed the mixture screws while watching the a/f meter to see if the mixture screws were functioning. Well, they were, just fine as long as the airflow was reduced.

I'm going to open the carb up again, and see if there is any restriction anywhere in the idle system, and if not, I'm going to open up the idle tubes to .037, and the mixture holes to .085.

It baffles me how this carb worked for years on three different engines, but doesn't today. Something has changed. I want to believe it is something outside the carb, but I can't.

If you think I shouldn't do the above change, or have a better specification, please post me.

Thank you for your help,
G. Carter

[Cliff Ruggles]

If it's lean at idle open up the idle tubes and the DCR's, that will put more fuel to the idle mixture screws.

An external APT screw would be a good idea as well, with a spring on it to hold it's setting.

You mentioned installing bushings, did you use our kit to do this?

Did you ever get one of our rebuild kits for the carb?.....Cliff

[MRSOFTE]

Hi there. I'm pretty new at the carb stuff, so I just recently got my carb rebuilt put it on fired the car up started no problem but as soon as the car starts to run fuel starts spraying from the top of the carb and the car stalls, from what I've been reading I'm guessing the float is being the problem? Just wondering if anyone knows why it's doing that and what can I do to fix it?  Thanks

Do you have a brass float? And if so did you drop it? If you answer yes too both questions I bet it cracked.
Just ask me how I know...ha! 

[Cliff Ruggles]

NEVER use a brass float in a q-jet.  The failure rate for all current production brass floats we've used (or attempted to use) here has been 100 percent. 

The latest production closed cell nitrophyl floats are excellent, zero failures to date with any of them, and they have better fuel control than the brass ones.......Cliff

[gregcarter]

Ok, I finally figured this one out, after basically remanufacturing the carb.

It was......... filthy, rusty, watery, dirty  gasoline.

I tried to start it one day and it wouldn't, noticed that no fuel was coming out the fuel line.

I emptied the tank, rinsed with phosphoric acid, rinsed with alcohol, and then acetone.

Then put a liquid liner in it and a new sending unit where the water laden air was entering nightly.

All this was expensive and stupid because a new tank was $90. The chemicals and liner cost more.

I flushed the lines and installed a new inline filter and a second one in the carb.

Fired right up and never stalled again.

So thank you Mr. Rugles for the carb lesson, I think I probably can fix one correctly now.

G. Carter

[Cliff Ruggles]

Good news!.....Cliff

[gregcarter]

Ok,Its not over yet.......
Thought I had it running good but it still kind of stank at idle as it always did for 15 years. The a/f meter said rich at idle and cruise.
A little history......
 This carb, an Edelbrock 1902, has 3 vacuum fittings on the baseplate.
The egr vacuum, the vapor canister, and the PCV lines.
This truck had a 6 cylinder motor in it stock.
When I converted it to a V8, I had a Rochester quad on it, and don't remember how I hooked up the PVC and vapor lines.
When I put the Edelbrock carb on it, I hooked both the PVC and vapor lines together with a T that was on the engine when I bought it. (per my mechanic partner)
The vapor line fitting was hooked up to the canister on a second fitting that opens a diaphragm that allows the vacuum from the manifold to suck out the trapped vapors in the canister.
It seems to me that the PVC line should go to PCV valve alone..
The vapor line should go to the cannister, and the diaphragm activator should just be teed into the same vapor line.


Can anyone direct me on this?

The richness need to be addressed.

I increased the idle tubes to .035 from .032 during the rebuilds.
Since its rich now, and probably always was, I should go back to .032s???
And since the idle mixture affects cruise, should I wait to change jets or rods?

I have:


main jets                                 .069

rods                                        36B


in there now.

The main jets have been in and out many times and don't look so good.

I didn't mention that the idle screws do little, it still runs when all the way in.

I just ran the motor with the idle screws in all the way, and had high O2 (.950-990) readings.

When I backed them out the motor slowed down.

What do you suggest?

Thanks ahead,

G. Carter

[Cliff Ruggles]

Correct, the PCV line should only be going to the PCV valve.....Cliff

[gregcarter]

Ok, I went ahead and replaced the .035 idle tubes with the .032's you sent and the idle appears controllable.

I took the truck to get smog checked and the co levels were 4 times higher (super rich)  than 2 years ago.

I had installed .042 lower mabs (there were no original lower mabs) and replaced the .052 upper mabs with .042s per your recommendation during the rebuild.

This is the only place I can think of that the richness was made.

In your recipes in the book, the smallest mabs are  .070, so I'm not sure why .042 were specified.

Should I yank the lower mabs back out, or drill upper and lower mab pairs out to get some air into the main system.

If you do recommend drilling them out, what size would be good?

Thanks ahead,

Greg Carter