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Woman's Tough Road Leads To Ownership Of Triangle Tires

Women auto shop owners aren’t rare anymore, but the story of Gina Paschall, owner of Triangle Tires in North Carolina, is definitely unique. According to The News & Observer in Raleigh, NC, Paschall, now 51, became a ward of the state at 5 years...

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Google Your Shop - What Do You See?

Go and enter the name of your shop at Google.com. Try putting quote marks around the name of your shop, like “Main Street Auto Care.” Now try entering the city where you are located with the name of your shop. What did you find? Your shop’s website?...

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Tennessee Shop Offers Discounts To Customers In Need

Price is often the biggest sticking point in an auto repair job. Some customers just have no feel for what certain services or parts cost, others have perhaps been treated poorly in the past (or are cheap), and some just flat out do not have the money....

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Hyundai: P0715 Code Leads to Replaced Transmission Speed Sensor

Complaint The customer states the check engine light is on. Cause Connected a scan tool and found codes P0715 — Input/Turbine Speed Sensor “A” Circuit. At idle, allowed the vehicle to reach operating temperature, checked the transmission fluid...

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Vehicle Unit Increase; Import-Rich VIO Are A Boon for Import Specialists

Need a dose of good news for your business? Then hear this: The influx of new vehicles in the market will lay the foundation for bountiful aftermarket service and repair opportunities. And, with import vehicle sales continuing an ­upward climb, there...

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Honda: Engine Shuts Off, But Power Mode Stays In ‘On’ or ‘Accessory’

Applies To: Honda Insight models with one-push start Customers might complain that when they shift into park and shut off the engine, that the power mode stays in On or Accessory. Honda says the culprit could be a misadjusted shift cable. If the...

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Brake Job: 2010 Ford Fiesta

What’s so significant about the 2010-current Ford Fiesta brakes? First, the Ford Fiesta is one of the first sub-compacts on the market with the “Full Monty” of ABS/ESC/EBC/TC to come as standard. 2014-current models even have torque vectoring. Second,...

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10 Alignment Tips to Help You See Past The Angles

1. Talk to the driver. Always ask questions at the time the vehicle is written up. Find out why customers think they need an alignment. 2. Take notes. Nothing is worse than a repair order that just says “perform alignment” or “needs alignment.”...

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What to Know About Modern Air Ride Systems

GM, Ford, BMW and just about every other manufacturer has a 10-year-old vehicle on the road with an air ride suspension at the rear or at all four corners. These systems could be as exotic as a Land Rover Defender or as common as a Ford Explorer....

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The Equipment And Tool Institute Reports Record High Membership Level

The Equipment and Tool Institute is starting off 2015 strongly with a record high membership statistic of 100 Members comprised of 88 Full Members and 12 Associate Members. ETI’s reputation in the automotive aftermarket tool and equipment segment...

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Modern Fuel Control Diagnostics: Sorting Through the Datastream

When confronted with a fuel control problem on a modern vehicle, contributing writer Gary Goms normally uses short- and long-term fuel trims to determine if the problem is caused by one of many failures such as a vacuum leak or a leaking fuel pressure...

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Hunter Releases New Technical and Training-Specific Channel on YouTube

Hunter Engineering Company has launched a new technical and training channel on YouTube, called the Hunter Learning Channel. The Hunter Learning Channel features extensive training video playlists for every product category manufactured by Hunter....

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Home Engine Diagnostic Dilemmas: Servicing Quadrajet Carburetors

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src=”/wp-content/uploads/Articles/05_01_2008/39766Carb4jpg_00000021239.jpg” border=”0″ ” align=”right” alt=”photo 4: float level can easily be measured on the quadrajet.”/>can be measured by inserting a special Kent-Moore float level gauge into the bowl vent located just aft the choke valve. See Photo 4.

Measuring the distance from the top of the bowl vent to the float and then subtracting the dimension from the bowl vent to the cover gasket can also determine the float level. If a repair manual with adjustment specifications is available, refer to the float level specifications listed for the model number stamped vertically on the driver’s side of the carburetor main body or on a tab attached above the primary throttle shaft. Although most Quadrajet float levels are set at 3/8”, the specification can vary from 5/16” to 1/2”.  Last, the metering rod piston can stick in its photo 5: metering rod travel can be easily checked by inserting an applicable tool into the front float bowl vent. bore, causing a lean air/fuel condition. The metering rod travel can be checked by inserting a screwdriver or punch into the bowl vent hole in front of the choke valve to see if the metering piston spring returns the metering rods to a raised position with the engine off. Spraying some penetrating oil into the bowl vent and tapping on the metering rod hanger with a screwdriver or punch can often loosen the metering rods. See Photo 5.

Quadrajet Adjustments
  The Quadrajet has a number of critical adjustments that make it perform better. The initial adjustment for idle mixture screws on most Q-jets, for example, should be lightly seated and then photo 6: metering rod travel can be easily checked by inserting an applicable tool into the front float bowl vent. backed out three turns. Initial idle speed can be obtained by seating the primary throttle plates and then turning the idle speed screw in about two turns.

photo 7: the secondary metering rod height adjustment should be checked to ensure delivering a correct secondary air/fuel ratio.Primary jetting is most easily corrected by increasing the jet size in two-step increments. To remove the primary metering rods, lightly tap the metering rod hanger with a screwdriver handle. Spring pressure will pop the plastic retainer from the main body casting.

  Before installing any Q-jet, make sure that the secondary throttle plates are seated and that the secondary throttle linkage is adjusted to specification. A tab on the primary throttle shaft actuates the secondary linkage. This tab determines the open position of the secondary plates. When the tab contacts the secondary linkage, the linkage pushes against the upper part of the secondary throttle shaft lever. At that point, the linkage should be located mid-point in the slot located below. See Photo 6.

photo 8: use a 3/32” hex wrench to loosen the lock screw on the air valve spring preload adjustment. On the topside, the secondary metering rod hanger should be adjusted to ideally achieve equal metering rod height and to allow both metering rods to touch the bottoms of their respective wells. This adjustment is done incrementally to avoid binding the rods in their hanger and to avoid damaging the hanger itself. See Photo 7.

 Secondary air valve adjustment is critical to Quadrajet performance because correct secondary air/fuel metering requires a constant depression or vacuum in the secondary venturis. If a repair manual with adjustment specifications is available, begin with the applicable spec. If a specification is not available, preload the air valve spring adjustment one-half turn, Photo 9: Make sure the secondary throttle lockout disengages when the choke valve opens.  then road test the vehicle. If the engine stumbles as it accelerates, increase the spring preload in one-half turn increments until the stumble disappears. See Photo 8.

Last, always make sure that the choke valve lockout is allowing the secondary throttle plates to open. Some Quadrajet models incorporate the lockout at the upper choke housing linkage while others locate the lockout  at the secondary throttle shaft. In either case, the choke valve linkage keeps the air valves closed until the engine warms up. See Photo 9.

Quadrajet Wrap-Up
When serviced correctly, the Quadrajet will prove to be a very responsive and economical carburetor to use for many street driving and racing applications. Although Quadrajet is very dependable, it pays to clean the external choke linkage and air bleeds with an aerosol cleaner. When changing the fuel filter, remember to replace the plastic gasket located on the end of the fuel inlet housing before reinstalling. Cross threading the inlet housing can be greatly reduced by cleaning and oiling the housing threads before installation. If the threads are seriously damaged, aftermarket kits can be used to replace the factory housing. In virtually all cases, a well-maintained late-model Quadrajet will maintain exhaust emissions within legal limits for collector and street rod vehicles while providing a full-bore performance experience.

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Gary Goms

Gary Goms is a former educator and shop owner who remains active in the aftermarket service industry. Gary is an ASE-certified Master Automobile Technician (CMAT) and has earned the L1 advanced engine performance certification. He also belongs to the Automotive Service Association (ASA) and the Society of Automotive Engineers (SAE).
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