techg8

I own and operate Everyday Performance LLC (www.everyday-performance.com), specializing in rebuilding and restoring Quadrajets.

This has ben a very good discussion of the things that go wrong with Qjets that result in flooding out. You have been getting good advise. Its a bit puzzling that it hasnt been sorted out with all you've tried.

Send it to me if you'd like and I will have a look at it, no charge. I would like to find out what is doing with your carb. If I cant find a reason for the flooding I will pay the shipping.

Sound good?

Ken G.

defiant1

Very good insight. I did try another accelerator pump plunger to see if any noticeable difference occurred, but the same symptoms were present.


PM sent

techg8

What kind of air cleaner configuration are you running?

I know a guy who had trouble with a drop base ram air type cleaner that would cause fuel to blow out of the top vent of the carb.

maybe the air cleaner's configuration or your carb's vent are causing a similar effect at speed.

Try driving around a little without the air cleaner installed and see if it occurs.

sammy

Attaching myself.....

TripDeuces

"I know a guy who had trouble with a drop base ram air type cleaner that would cause fuel to blow out of the top vent of the carb."

This is a valid point and I've seen it when air cleaners aren't used but not with them on but I suppose anything can happen. Air under high speed moving over the vent will siphon the fuel right out. It was so bad when it happened to me that the windshield got covered by a geyser of fuel. (the hood was off at the time) Just putting the air cleaner back on stopped it. I also used to put a piece of 3/8 fuel line over the vent to extend it a little bit. Cut the end at a 45* angle and face that part forward but only do this if you have room under the air filter lid. You don't want to flatten the end out under the lid causing a smaller opening. The bowl needs to see atmospheric pressure.

defiant1

I have the outside air induction with a 2" air cleaner spacer resting on top of the carb. As I indicated in a previous post, inside the spacer is completely dry. All the gas leaks from the accelerator pump area and wicks through the gasket as well dumping fuel on the drivers side of carb.

d1

carbman

carbman

That QJet will not handle 6 to 6.5 lbs fuel pressure the later qjets that use the float with longer lever FL8 is the Hygrade number might but that early carb will not.Your Qjet likes 5 to 5 1/.4 nothing more Qjets will function with 3 to 4 lbs if volume is there. That's just too much fuel pressure.


Carbman

carbman

I posted earlier about your problem but here goes again: The earlier Qjets with shorter float lever will not tolerate 6 lbs or higher fuel pressure, the laterqjets that use float with longer are such as Hygrade FL8 might but it will be marginal Qjets like 5 to 5 1/4 lbs no more, they will function down to 3 or4 lbs if the volume is there. The later float cannot be used in your carb. You just simply have too much fuel pressure.
Carbman

TripDeuces

"Qjets like 5 to 5 1/4 lbs no more"

I have to disagree with this for one reason and one reason only. The 1966 'Motors Auto Repair Manual' lists under 'Tune Up Specs' that the fuel pressure should be 7.75-9 psi in 1966 and 7-8.5 psi in 64 and 65 for all V8's. The straight six and V6 are the only ones listed at lower pressures but are not QJets.

With that said I personally do not like a lot of pressure at the carb inlet. If you can maintain 5 psi with sufficient volume you'll be just fine. All you have to do is keep the bowl full and the carb will work fine. Carbs do not run on fuel pressure but rather atmospheric pressure. Keep the fuel bowl filled and the jets covered and they will work without a problem.

Since you have a regulator you can perform your own simple test and reduce the pressure down to say 3 psi and see what happens. If you're still spilling fuel out the top of the carb then you know you have an internal issue with it.

carbman

Funny the 66 Chevrolet Chevelle Chevy II factory shop manual shows 5 1/4 to 6 1/2 lbs max for all 283 327 396 and 427 with Rochester and holley carbs the factory must know what they are doing, they designed them.A lot of these replacement pumps are anywhere from 7 to 9 to even 12lbs

defiant1

Ok.... I do not have a regulator. So do I replace the mechanical fuel pump with one, known to have a certain fuel pressure range that does not exceed 5 psi? Or do I install a regulator?

d1

TripDeuces

Get a cheap regulator like what used to come with Holley pumps or if you want I have one I'm not using and for the cost of shipping I'll send it to you so you can test what you have.

carbman

I would install an adjustable regulator if underhood cosmetics allow it and set it at 5lbs.
Some more info not related to fuel pressure, back in the day fuel initial boiloff point was 210 deg now its down to 150 which can sometimes cause excessive cranking after a heat soak. Using a 180 stat instead of 195 will help somewhat never a 160 as engine wear increases by abt 20% with a 160 stat.Talking about flooding back in 1957 when Holley came out with the 4150 it had mysterious flooding.Holley supplied a float with longer lever to help it hold needle on seat they called it High Leverage Float.Your prob is just too much F pressure. I have specialized in carb and ignition as a sideline since 1970 including Corvette K66 ignition and Olds UHV. Matter of fact I have2 usable UHV amplifiers 1 Red coil and 1 red used dist cap.


Regards,
Carbman

tcarroll

Interesting thread as I am having almost the identical problem with my 1971 Rochester rebuild. Please let me know if you find a cure even if it was replacing the carb.

Thanks Todd

carbman

If you do not have a fuel pressure problem, not over 5lbs it's likely you may have a sunk float.The modernday crappy fuels are notorious for absorbing into the float. Make sure the you don't have a bad needle and seat as lot of them nowadays wont pass a vacuum test. Put a vacuum pump on the seat with the needle in it and see if it will hold vacuum. Two more things make sure the needle pull clip is not through one of the holes in the float arm.It hooks over the float arm away from the needle and seat on the little lip that sticks out towards the float pontoon. Also be sure the gasket and seat under the float needle seat is okay.Plus make sure the little float pivot wire is being held down when the carb top is installed I usually just open it slightly so the carb top will hold it down.


Hope this helps,


Carbman.

tcarroll

I have looked at all the things you have mentioned crabman. New fuel pump, High flow good quality needle and seat bought from quadrajets.com and put in a new float. New top gasket again, still floods out intermittently.

classicmuscle442

Sounds like a fuel leak near fuel inlet/fuel filter into carb? Engine runs good, carb. issue would show under WOT.

MDchanic

Yes, but have you tested it?

Remove the airhorn, leave the rest of the carb in place, empty most of float bowl, disconnect ignition, crank engine while holding float pivot down with one finger and watching float bowl.
Fuel level should rise, then stay level about a quarter of an inch below the top.
If it keeps rising, then you need to figure out why.
Use the other hand to gently lift the float up and see if that stops the flow - if so, this could be a heavy or misadjusted float. If not, then you've got a sealing problem somewhere.

Don't smoke while doing this.

- Eric

carbman

Yes but just what is the fuel pressure? I assume nothing wrong with carb main body, bad threads where seat screws in, why do you need a highflow needle and seat, the larger the needle seat the higher the fuel level will be, or no hairline cracks in carb main body (rare) as I have said before that Qjet won't like over 5lbs fuel pressure.

brown7373

It sounds like an internal leak. How about the quality of the parts in the kit and the needle & seat. I am NOT saying Quadrajets.com sells inferior parts, but I am not familiar with them. I have been buying my kits from www.cliffshighperformance.com for the past 10 years or so, because I KNOW his kits are impervious to the various fuel additives. Rubber that is not impervious to the additives will usually leak from deterioration or distortion of the rubber. Cliff is not the only one who sells quality parts & rebuild kits, but there is a lot of junk sold out there, and some companies that rebuild carbs install junk kits.

tcarroll

Well the needle is new so the rubber is not deteriorating...yet and it only does it sometimes which leaves out a bad needle and seat and float which have been changed, checked and re-checked. When I got home form the car show it idled perfect??????
It seems to be when I come off the highway back down to speeds in town when it loads up. The gas appears to be percolating inside the carburetor??? What causes that if the engine is running at a normal temperature???

tcarroll

By the way loads up real bad with air cleaner on... not off. Sorry to whoevers thread this is I did not mean to highjack it and please let me know if you have solved your issue and how? thanks Todd

carbman

Have you actually checked the fuel pressure? You say you have a new fuel pump. Iv'e seen these after market fuel pumps put out 78910 even 12lbs which is pure junk.Check the pressure with a known good fuel pressure gauge. Also check the needle/seat combination with a vacuum pump to see if it holds just saying its new doesn't mean its not leaking. If the fuel pressure is at or near 6lbs the jiggling of the car on the road will cause intermittent flooding as the pressure is right at the floats ragged edge of control


Carbman

tcarroll

I will check the fuel pressure as soon as I can, today I have work and need to make hay when the sun shines. The fact it is intermittent makes it hard for me to believe it is the new needle or fuel pump but hey I will go through the motions to eliminate them out of the equation.

BlackGold

Intermittent means that you should believe anything is possible, not that you should dismiss suggestions out of hand. The tougher a problem seems, the more you have to be willing to test theories, not assume they aren't possible. Good luck with your diagnosis.

tcarroll

Well the fuel pressure maxed out at 6lbs which according to specs it should be 5 to 7 lbs. I put a tapered fitting into the fuel inlet and check to see if the needle would hold vacuum. It did not. I guess a new needle and seat is in order and take it from there.

tcarroll

found some gunk at the bottom of the seat, cleaned it out and the needle and seat held vacuum. I found this film of gunk in the carb once before in the seat. Do you think a gas cleaner will do the trick or do I need to take off the gas tank and clean it out? I did this prior to installing the tank. I'm going to try a gas cleaner first see what happens.

tcarroll

I have added gas cleaner to the tank, re-checked float level and cleaned out seat and needle it is now holding with a vacuum test.
The pump pressure was 6lbs at its maximum pressure.
I put in a phonelic 1/2 inch spacer between the intake and the carb
I have replaced a leaky vacuum advance and checked the one way check valve on the brake booster and checked the vacuum line going to it.
Car is running better but still has a slight hesitation when you first touch the gas pedal and idles good at times and not so good other times, no rhyme or reason to this. Yes I have a new accelerator pump in the carb. I'm thinking maybe the 67 jets are a bit lean now.
I have not tried it on the highway to see if it will flood out like it was when I get off the freeway. I guess that's my next step.

MDchanic

You have already found crud between the needle and seat. That means other crud also probably got in there, and who knows how much made it through, and may be floating in and out of the jets.
More to the point, the fuel pickup sock and fuel filter are there to prevent exactly these sorts of particles from getting into your carburetor, so you need to find out why these got through, because there are more behind them, waiting for their chance.

- Eric

tcarroll

Sender and sock are new and I have a fuel filter before the pump and now after the pump as well. I think it was some varnish from the gas line. If I see any more i will be pulling the tank.

Kenrock81

Tedd Thompson

All though your problem is related to this thread it is 6 years old and a response from the OP may not happen.
As I read it the problem was resolved by cleaning the needle and seat and checking for junk in the lines and tank.... Tedd

Fun71

What issue are you having? Since you quoted defiant1, are you experiencing flooding due to the float arm pin not being secured in your carburetor?

Kenrock81

I'm experiencing leaking from the accelerator pump. I've taken it apart I've cleaned it I've adjusted the float to 11/32 per specsheet. Fuel filters brand new. accelerator pump was replaced a little over a year ago when we rebuilt the carburetor. Had no problems for about a year. Then it suddenly began to choke on itself and I found that it's leaking through the accelerator pump. I was just wondering if the little clip that holds the needle onto the float fulcrum was supposed to be so loosely attached. as far as I can tell the needle seats right and there's no gunk at the seat.

Kenrock81

And thank you for responding to the post. I greatly appreciate your time

Fun71

Yes, the clip is supposed to be loosely attached, and from what I recall reading recently there is a particular way the clip is supposed to be attached to the float arm. I have not experienced any issues with having the clip attached various ways, or even when I neglected to install it.

Are you saying there is so much fuel leaking around the accelerator pump shaft that the carb is flooding? If so, and the float is adjusted correctly, are you sure the float is not leaking and sinking into the bowl, thereby allowing too much fuel into the float bowl?

Kenrock81

Yes itt does choke on too much gas, I've thought of that. would you recommend switching to a brass float??