Home Up

The new float, needle, needle retaining spring, and float pivot are all in place. You can see the position of the pivot. Don?t reverse it.

For more clarification, here is another shot of the installed float, needle and set from the top. Don?t confuse the metal sheet above the secondary throttle plates for the air flap. But the sheet metal is important. It helps direct air flow through the secondary. If yours came out during cleaning, just slide it back in place.

If you haven?t found it by now, you need it. The screwdriver is touching the carb number. The number is stamped into the body on the driver?s side. This is usually either a 7 or 8 digit number. You will need to locate and record it so you can look up the specifications for you particular carb. These specs will be needed for more adjustments. The first one is the float level. Find the spec sheet with your rebuild kit, locate the car, locate the carb number and follow the chart across for the different specs. It may be easier to underline the line you need for a quick reference point. It saves time finding specs later.

Now you need to adjust the float. This can be very tricky, and it?s very important. The float needs to be in its upper position, like it is floating in fuel. To do this, you must press down GENTLY on the needle and seat end of the float. This will cause the opposite end of the float to rise. BUT you MUST be sure to hold the float pivot firmly in place at the same time. The pivot tends to lift when the float seat end is depressed. If it lifts, the float adjustment will be wrong. THIS IS CRITICAL. If the float is not correct, nothing will be correct. You can see I am holding the float pivot down with one finger and depressing the float with the other finger. Not the buoyant end of the float is rising up in the float bowl. Look just to the right of the pivot. You can see a small notch in the float support lever. Both sides have this notch. This is where the float is adjusted. Slightly bend these tabs/notches to adjust the float up or down.

You can see the mark on the ruler I drew with a pen. This is the float spec found in the spec sheet. Just make contact, without any pressure, on the toe of the float. You can see a line at the end of this float. That where you want the ruler, or float gauge. Be sure not to get the gauge on the curve at the end of the float, but be as far out on the flat top as possible. That where the line is, if you float has one. Most of the fiber floats have them. Older style brass floats usually do not. With the float in the raised position, your mark should be dead even with the top of the carb bowl body. Adjust as needed. Be PICKY! This is critical!

Once the float is set, just let it drop back down in place. With the top in place the pivot won?t raise, and the float will work fine. Drop the two plastic pieces back in place. The round one is used for two different things on newer carbs. In trucks it is used for a solenoid to control a limited accelerator pump shot when the engine is warm. This is done for emissions purposes and can sometimes hurt acceleration. It works better disconnected, but that has to be for off road operation per the Feds and emission laws.
It is also used to house the connectors for the mixture control solenoid starting in 1981 for computer controlled cars. If you have neither one, just drop the round plastic piece back in place. If the plastic piece is not there, don?t worry about it. However if you carb originally had the odd shape piece above the float and needle/seat, it MUST be put back in or the carb will have flooding problems. Some older yet carbs use a small metal clip in place of this piece. If it used the metal clip, the clip holds the float pivot in place, and must be there to prevent flooding.
Early Qudra-Jets have a smaller front chamber, and there is no space for the round piece. These usually have the metal clip. The float installation and setting procedure is the same for all of them.

Now put this spring back in. The spring holds the primary metering rods in the up or rich position. Engine vacuum pulls them down. At closed throttle, vacuum is high and the rods are in the down position, leaning the mixture. Open the throttle and vacuum drops, and more fuel is allowed. Stretching this spring will cause the mixture to richen quicker in throttle opening. But this is a poor way to adjust the carb. It?s too vague and hard to calibrate. Change the primary jets and rods instead. Not only is it controllable to change the parts, its reversible.

Now set the primary metering rods and pistons back in place. Don?t force anything or you will damage the rods. This can be a bit tricky. You must be sure the rods are going into the jets, and not binding. You can see the small alignment pin on the piston. It drops into carb body, and can hit the adjustment in front of the piston. Remember, the adjustment is the lean stop for the primary metering rods. Again, most of the time you don?t want to change this adjustment. This should only be done on a flow bench or a running engine with a gas analyzer. The plastic retaining ring around the piston will need to be gently pushed don in place into the carb body. This will keep the assembly in place.

A screwdriver works well to press the retainer backing place. Press on one side, then work your way around until it?s fully seated.

Now you can put the top carb gasket in place. This is also known as the air horn gasket. The top metal section of the carb is the air horn. You can see the gasket is cut to allow it to be positioned around the metering rods.

Place the gasket on the alignment pins. You will often find there are different gaskets in a rebuild kit. Make sure you compare the original gasket to the new one. (you did save it didn?t you? ) You won?t need to other ones in the kit.

This is the accelerator pump. Some kits supply you with a completely new one. Most don?t. You may just get the new seal which installs on the end (top in photo) of the pump. The coil spring that wraps around the top comes off. Just stretch it a bit with a small screwdriver or pick to remove it. Then use the same tool to remove the old seal. The old seal is gone in this shot. Age killed it. Put the new seal in place with the center round section on first, and the taper pointing to the end, or top of photo. Reinstall the spring on the pump, inside the seal lip.
Some kits supply the pump shaft and seal but don?t supply the larger spring and spring retainer clip. Just transfer it from the old shaft to the new one.
Lube the seal before installing the pump. You can use almost anything. White lube, WD40, motor oil, etc. Just a little bit will do it. Avoid heavy grease. Gas can be used if the carb will be installed and operated right away. But gas dries out, and the seal can stick when operated. So use one of the other lubes.

Install the accelerator pump return spring. If you leave this out, the accelerator pump won?t work. This spring can be stretched a little bit to increase tension. Most of the time it?s not necessary, but if the pump did not return to its full travel you will need to increase tension.

Now insert the accelerator pump in place on top of the spring. Be sure not to damage the gasket. The pump rod will need to be put through the gasket once in place in the carb body.

You will notice the gasket won?t sit down all the way due to the accelerator pump spring pushing it back up. Just be careful of the gasket so it?s not damaged during reassembly.

Line up the air horn with the carb body. Take care to be sure the tubes are lined up with the gasket and carb body. Guide the accelerator pump rod through the air horn. Be sure to drop the air horn down even with the body, not on an angle as shown in the picture. The picture was done for easy viewing. If you don?t drop it down straight, the tubes will be damaged and the operation will suffer.
You may find it helpful to hold the accelerator pump and gasket down in place with a thing blade or putty knife. Slide the putty knife out when the air horn is down in place.

If you have a 1981 or newer carb you must use the putty knife or similar item to hold the TPS plunger in place during assembly

Install the tapered screws first. These may be a torx (star) head. The screwdriver blade is touching one of them in the photo. Between the tapered screws and the alignment pins the air horn and gasket are held in proper position. Snug the screws, but don?t tighten them yet.
Install all the remaining air horn screws, and snug them all.
Now go back and tighten them, starting with the tapered screws. Then work your way out in a circular pattern, tightening all the remaining screws.
If you tighten one side than the other, you could warp the air horn and carb body.

Now drop the secondary metering rods back in place. You can see them being inserted through the top of the air horn. Again, the carb must be level and you must be careful to drop the rods into the secondary jets down inside the carb. This can be easy, but it can be tricky. Don?t force anything or you will cause damage. The secondary rod holder will sit in place without force when everything is installed in position. Then install the retaining screw in the holder.

This is the fuel filter housing. Be sure to install a new plastic gasket on the bottom of the housing. If the old one is in very good condition you can reuse it, and save the new one for later filter changes. It does not need to be changed every time the filter is removed.

The filter has a check valve inserted into the end. This is to keep fuel from exiting the carb flow bowl in case of an accident or rollover. The valve end goes to the inlet side of the filter housing. The spring goes into the carb body first, then the filter, then the housing. If the spring is not there, fuel will bypass the filter. You don?t want dirty fuel in the carb. The filter could also move back and plug the inlet and create fuel starvation with a missing spring. Do not apply any sealer to the threads of the housing. They don?t seal, the gasket does.

This housing still has the fuel supply pipe attached. Someone cut the line and use neoprene hose to connect the line. While functional, it looks bad. And the neoprene could become kinked, creating a fuel restriction. It will be replaced on this car after the carb is finished and adjusted.

Now you can reinstall the choke housing and linkages. You may need to go back to the choke disassembly pictures to recall how to connect and install the choke parts.
Then set the choke coil tension. You can see the index in about the 1 to 2 o?clock position on the housing. This choke coil/cover has a notch that in located by the tab and retaining screw in about the 2:30 position. This presets the choke in its correct position. But you may find the choke will perform better if you use the index and turn the choke coil two notches counterclockwise. This richens it up a bit and improves cold and midrange warm up operation. You have to trim the retaining tab away to make this adjustment, or just use a retainer without the tab. Older carbs do not use the notch and tab. Instead they have a mark on the choke cover to align to the index on the housing. Which index point is shown in the spec sheet. You may also set these a bit rich if needed.

This is a float angle gauge. It is set on the choke plate and set to zero level. Then it is adjusted to the number given for choke pull off on the spec sheet. The display on the gauge and the spec in the book are in degrees. Some spec sheets will also give a measurement for use when you don?t have a choke angle gauge. Both are used to adjust the opening when the car is first started.
The choke must be fully shut to start the car cold, then open a bit right away when started to prevent flooding. As soon as the engine builds vacuum, the vacuum operated choke pull off goes to work and opens the plate.

You can see the angle gauge set for specs. Now the bubble needs to level out. This is the choke pulled open. The pull off can be either pushed in manually, as shown here, or a vacuum source can be applied to pull it open. The vacuum pump is the preferred way. It causes the pull off to seat in the correct position. Manually depressed it can be a bit off. It will be close. Why do this one manually? The pull off is bad and needs to be replaced. Of course replacement will require readjustment.

To adjust the pull off, just turn the screw on the pull off as shown. Turning the screw in will raise the lever on the pull off, and cause the choke to open less. To open the choke more, turn the screw back (counter clockwise). Keep an eye on the angle gauge, or the opening measurement.

At the left side of the photo you can see another vacuum pull off. This is the secondary choke pull off. It is also vacuum operated and does pull the choke open, but at a greater angle then the primary pull off. Check the spec sheet, readjust the reading on the angle gauge, and set the pull off by slightly bending the linkage with the tool shown above, but not on the linkage shown. Use the linkage that attaches to the pull off.

The rod the tool is on is the secondary air flap adjustment. With the primary pull off fully seated, vacuum applied position, this rod need to hold the flap fully shut, but not cause the pull off to bind and not fully seat. The function is to not allow the secondary air flap to open until the engine vacuum drops with open throttle. This is part of the term ?Vacuum Secondary? If the secondary flap opens too soon, the car will bog and hesitate.

Now the most important of all for all of you performance guys. This is the secret to optimum performance for the secondary throttle opening. This is when you foot first hits the floor. The secondary air flap tension spring

Just under and behind the adjustment being made in the picture, you will find a set screw. Looking through the lever the link is attached to, you will see another adjustment screw. There is a spring which can be seen under the edge of the air horn that the side screw adjusts. Loosen the set screw and turn the side screw to loosen the tension on the spring, turn the adjustment screw until the spring touches, and then additional turns as specified in the spec sheet. This is the real biggie, and most ignored adjustment on the Qudra-Jet. And it?s tunable to match the engine and car. Too little tension and the car bogs. Too much tension and the secondaries open too slowly. You can slowly decrease spring tension until the car bogs going into the secondaries, the just barely tighten it to stop the bog. This will allow the secondary air flap to open as soon as possible without bogging. Translation, maximum response. 1/16 of a turn makes a difference

This and one other adjustment have earned the Qudra-Jet the nickname Qudra-Bog. The problem is not the carb, but the lack of correct adjustment. Translation, the tech working on it goofed, or did not take the time to set it. It is usually not done by anyone not familiar with the Q-jet. Even experienced techs miss it on a regular basis.

Now put the carb back on the car. Tighten it down, adjust the throttle linkage and the transmission linkage, if it has one. Prime it with a bit of fuel, and fire it up.

Be sure to check for fuel and vacuum leaks anywhere on the engine or carb while it?s warming up. Allow the car to fully warm up. Make sure to slightly open the throttle and allow it to come off of fast idle.

Granted this shot is from the carb torn down, but it clearly shows the idle speed screw just above the screw driver tip.

Set the idle speed to specs. You will probably do this again. When you installed the mixture screws you set them to an even position. Continue to turn them equal amounts. Start by turning them in a bit. If the engine slows down, turn them back out until the engine speeds up then levels out. Now turn them back in as far as you can go without slowing down the engine at all. If the engine started speeding up when you turned them in, keep turning until engine speed levels off, and again stop at the point just before it starts to slow down.
You can also watch an attached vacuum gauge and peak the vacuum. Have the screws in as far as possible without vacuum dropping.
Now you will probably need to readjust the idle. If idle speed was off more than 100 rpm, recheck the mixture screws adjustment.

Again this is with the carb off the car for clarification. The small screw in the center of the picture, pointing to the right, is the fast idle screw. This is the last adjustment, and done with the engine fully warm.
Open the throttle just a bit, and close the choke slowly until the fast idle cam lifts. How far depends on the spec sheet, then shut the throttle. The car will now be on fast idle. Often it is set on the second step, or third step, and sometimes on the high step of the fast idle cam. This means that the fast idle screw is touching the specified step on the fast idle cam. Then set the screw to fast idle specs.

You may find for some custom engine builds, you may need to change to larger jets and smaller rods. This is usually only necessary in the primary section , and the secondary section can operate as is. Other changes including choke, fast idle, and float height may be needed based on your engine build up.

YOU DID IT! Now go drive that thing!

Ken Styer

Home Up