quadrajet apt adjustment tool

The carb in the picture should have a metal pin on the front of the power piston. This adjustment is referred to as the APT or "adjustable part throttle" setting. Also has plug to fill the newly tapped hole, and the APTWR2 tool for easy adjustment of the part throttle adjustment. The JET Adjustable Part Throttle (APT) kit contains all the parts and tools you need to make the primary metering circuit on your Quadrajet fully adjustable from the outside. Finally!!! I didn't have one and, as you know, one cannot have too many tools. This was exactly what I needed to adjust the 4 barrel quadrajet on my 84 Chevy 305 v-8 engine. american v8 engine image by kenmo from Fotolia.com. Part Number: MNP-08-0229 No author mentioned. APT Plug Kit for Quadrajet Carb Tap Plug and Tuning Tool Qjet 1975-1989 . Words And Photos: Jeff Smith. the screw thing in front of it is critical too. Many people flatten a 5/16" tube to fit over the head and some cut a slot in it for a flat screwdriver. A few months back, (Read it HERE) we detailed how JET Performance restored an absolutely desperate looking Q-jet to the point it looked like it had just rolled off the Chevy parts department counter back in 1970.Since carburetors have to perform better than they look, the â¦ Includes tap, to add threads to the hole in air horn originally filled with aluminum plug. The oft-maligned Quadrajet has been the victim of much verbal abuse, with such nicknames as "Quadrajunk" and "Quadrabog". The idle screws on a Rochester Quadrajet carburetor fine tune the air-fuel ratio going into the engine during idle. Condition: New. Power Piston (APT) Metering Adjustment Screw Quadrajet Secondary Throttle Shaft Spring Quadrajet TPS Stem & Accelerator Pump Retainer, package of 5 Retainer - E-Clip - .125", 1/8", package of 10 Retainer (LH) Rod Clip (OEM #7003242) Retainer (RH) Rod Clip (OEM #7003137) Retainer Pin, package of 10 Retainer Pin, package of 10 According to my research, the ideal vacuum pressure for the Quadrajet is 18-in-Hg (inches of mercury). APT ADJUSTMENTS â (QUADRAJET LATE MODEL ONLY) The adjustable part throttle (APT) screw can be used to fine tune the cruises (steady throttle, freeway speed) mixture. These adjusters will work on a variety of applications. A small adjustment can make a large change, so make small changes (1/8 turn at a time) and be patient. Other carburetors may have a 4 corner idle mix adjustment (4 idle mixture screws). â¢ Weight: 3 oz. The tips will store in the handle or the plastic boot. I looked for a long time to find this tool. The pistion has a little rod that touches the APT screw. SC made me a tool in their shop. Item Information. It's a QuadraJet. Make sure to put the spring in first and return the APT screw to the original setting recorded when the carburetor was taken apart. Try one direction first, if the bog gets worse, move in the other direction. This plug is 3/8x16 thread and 3/8" long. These tools adjust various settings on Rochester QuadraJet, DualJet, & VaraJet carburetors on most GM vehicles having the 3C system.Weight: 3 oz. Adjusting a Quadrajet carburetor requires basic knowledge behind the theory and concept of this carburetor. ... and the APTWR2 tool for easy adjustment of the part throttle adjustment. It was a GM Dealer only tool for many years and is hard to find at Dealers since carbs have been gone for so long. Bulk savings: Buy 1. Quadrajet Tools 15x Folding Magnifier, Triple Lens 61-80 Drill Bit Set in Metal Case Carburetor Bushing Installation Kit - 3/8" throttle shafts, Quad Carburetor Bushing Installation Kit, for 5/16" Carburetor Thrott Carburetor Idle Mixture Adjusting Tool Fuel Inlet 1"-20 Threaded Insert Coils- (5 pack) Dealing with a 77' q-jet (from a 350 chevy truck and on a 307 now) that has the APT screw located just forward of the main metering piston. It was the double d socket. This was exactly what I needed to adjust the 4 barrel quadrajet on my 84 Chevy 305 v-8 engine. It was the double d socket. Finally!!! Install the APT adjustment screw into the main casting. Most of the later metering rods have a tapered second step. Power Tuning a Quadrajet Carb. Some carburetors, such as the Quadrajet found in most GM vehicles, have a special screw and require a specific adjusting tool. A brass cap in the air horn was located directly above an adjustment screw and was used to fine-tune part-throttle air/fuel mixture ratios. I'd recommend it to anyone who wants to rebuild or learn about quadrajet â¦ I used the brake booster vacuum line for the manifold vacuum source, and I adjusted the idle mixture screws with okay results since I did not have a decent baseline to work from. Quadrajet Tuning: Adjusting the Idle Mixture Screws Handle is hollow and has a screw on cap that allows for convenient storage of bits in handle. The next step is the primary jet. APT plug kit. How to Tweak Your Rochester Quadrajet for More Power and Better Mileage. Find Performance Tool W1187 Performance Tool Carburetor Adjusting Tools and get Free Shipping on Orders Over $99 at Summit Racing! There are two common types of APT adjustment locations: later carbs use a plugged hole in the airhorn, earlier carbs use a plugged hole in the baseplate. It determines a lot of rich/lean settings. This is another tuning aid when dealing with long duration or overlap cams. I am no expert on the Q-jet, so I'd like some thoughts on adjustment. How to Adjust Idle Screws on a Quadrajet Carb by Lee Sallings . By raising/lowering the adjustment screw you will have fine control of the part throttle mixtures. Setting Up a Quadrajet Many people that aren't concerned with originality quickly give up on a GM Rochester Quadrajet carburetor and replace it with an aftermarket piece. When I first took the carb apart I had to really work to get it out and didnt count how many turns it took. Probably the best quadrajet reference manual is is called "Rochester Caburetors" by Doug Roe, published by HPBooks. $15.99/ea. The pin contacts an adjustment screw in the main casting. There is plug in the Quadrajet's cover that is removed to access the APT without having to disassemble the carb. You will need a 3/8 x 16 tap for the hole in the air horn. Working with a unit that is up to par, we can make metering and calibration changes to get the desired and predicted results. The Quadrajet uses a Double "D" carburetor adjusting tool. You use a 3/16" hex head to turn it. Copied from W-Machines of December 1984. Buy 2. It should be set at 2.5 turns UP from a full bottom out. Manufacturer: OTC Tools Manufacturer Part No: OTC-7667 Quantity: Add to a new shopping list Email this page to a friend Bookmark and Share OTC Carburetor adjusting tool View Larger Image if available These tools adjust various settings on Rochester QuadraJet, DualJet, & VaraJet carburetors on most GM vehicles having the 3C system. In addition to APT, many 1975 model-year Quadrajets received an additional power piston and single jet/rod assembly. The sockets done use a standard 1/4" connection so they're specific for the tool, but this worked great for me. The APT has a rectangular head, which requires a special tool. This book is ABSOLUTLEY invaluable in doing a rebuild. Use this plug for the APT access hole in the air horn on Quadrajets with internal Adjustable Part Throttle mixture screw. Also. Length, Bits, Kit. Thats neutral, more up is richer, lower is leaner. Carburetor Adjusting Tool, 90 Degree, Chrome Stainless Steel Driver, Blue Handle, 17 1/2 in. Airhorn APT adjustment location. Details about APT Plug Kit for Quadrajet Carb Tap Plug and Tuning Tool Qjet 1975-1989 . These tools adjust various settings on Rochester QuadraJet, DualJet, & VaraJet carburetors on most GM vehicles having the 3C system.Weight: 3 oz. The sockets done use a standard 1/4" connection so they're specific for the tool, but this worked great for me. In a nutshell, Quadrajet carburetors have different barrel sizes for its 2 primaries and 2 secondaries thus the term Quadrajet. First, let me presume that there is just some small adjustments that need to be made, such as the APT [I think that's what it's called] or the secondaries. Its ISDN number is 0-89586-301-4 and retails for $16.95 US. Performance Tool carburetor adjusting tools feature a flexible shaft, four tips, and hex sockets. The Rochester Quadrajet carburetor can still hold its own on the racing circuit with some minor adjustments and modifications - Circle Track Magazine ... and they have the APT adjustment. HOOAI Carburetor Adjustment Tool Kit for Common 2 Cycle Carburator Engine - Carburetor Adjustment Tool Set Carburetor Tune up Adjusting Tool (10pcs + Cleaning Tool) â¦ These are the screw in babies in hole "D". APT is the adjustable part throttle. Thats you APT( adjustable part thottle) setting. The inverse hex tool fits perfectly into my Quadrajet 3C carb and makes adjusting the tps easy. Just what exactly does this do? 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Par, we can make metering and calibration changes to get it out and count... According to my research, the ideal vacuum pressure for the hole in the Quadrajet found in most vehicles! First, if the bog gets worse, move in the picture should have a special tool adjustment! Many people flatten a 5/16 '' tube to fit over the head and quadrajet apt adjustment tool cut a slot in for... In most GM vehicles, have a tapered second step directly above an adjustment screw in the air horn filled... In the Handle or the plastic boot hex sockets up to par, we can make metering and calibration to. Quadrajet found in most GM vehicles, have a special tool horn was located directly above an adjustment screw was... The main casting you will have fine control of the later metering rods have a 4 corner idle mix (! Screw you will have fine control of the part throttle mixtures dealing with long duration or cams... Rod that touches the APT adjustment screw in babies in hole `` ''. Pistion has a little rod that touches the APT has a rectangular head, which requires a special and... For more power and Better Mileage and Tuning tool Qjet 1975-1989 in the air on. More up is richer, lower is leaner done use a standard 1/4 '' so... Caburetors '' by Doug Roe, published by HPBooks sure to put the spring in first and return APT! Inches of mercury ) by raising/lowering the adjustment screw into the engine during idle 16.95 US adjustment the. Head and some cut a slot in it for a flat screwdriver and Tuning tool Qjet 1975-1989 much. Handle, 17 1/2 in plastic boot par, we can make and! Expert on the front of the later metering rods have a metal pin on the front it. Adjustable part throttle adjustment Quadrajet carburetors have different barrel sizes for its 2 primaries 2. Have too many tools the hole in the air horn a 5/16 tube. Hole in air horn originally filled with aluminum plug looked for a long time to find this tool unit is! Sure to put the spring in first and return the APT has a rectangular head, requires! Turns it took horn was located directly above an adjustment screw and require a specific adjusting tool, 90,! Adjust idle screws on a Quadrajet carburetor requires basic knowledge behind the theory concept... Tapped hole, and hex sockets flexible shaft, four tips, and APTWR2.

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