How to rebuild a Rochester Quadrajet 4MV carburetor
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The article is also meant to complement the rebuild guide books available, shedding extra light on any topic or procedure that may require further explanation. In the future, as time allows for updates, the article will cite sections and passages from related books to help the reader follow along with ease. | The article is also meant to complement the rebuild guide books available, shedding extra light on any topic or procedure that may require further explanation. In the future, as time allows for updates, the article will cite sections and passages from related books to help the reader follow along with ease. | ||
| − | Although the article specifically deals with the Rochester Quadrajet (aka "Q-jet, qjet, etc.) 4MV model, the information found here is useful for working on other Rochester Q-jet models as well. | + | Although the article specifically deals with the Rochester Quadrajet (aka "Q-jet, qjet, etc.) 4MV model, the information found here is useful for working on other Rochester Q-jet models (including the Dualjet (which is the front half of a Quadrajet) as well. |
At times, the reader may encounter differing viewpoints, especially when dealing with certain repair options. It is up to the reader to decide which method works best. If confusion persists or further advice is needed, it is highly recommended that the reader visit the [http://www.hotrodders.com Hotrodders] forum and ask for assistance from fellow members. | At times, the reader may encounter differing viewpoints, especially when dealing with certain repair options. It is up to the reader to decide which method works best. If confusion persists or further advice is needed, it is highly recommended that the reader visit the [http://www.hotrodders.com Hotrodders] forum and ask for assistance from fellow members. | ||
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==Other considerations== | ==Other considerations== | ||
| − | *When getting a carb from another vehicle, whenever possible, get the factory cable bracket. Even if you're using an aftermarket intake, it might come in handy for making up your own bracket. And regardless if using an aftermarket intake or not, the bracket can be used to measure the correct cable/carb relationship for setting up whatever bracket that's used. | + | *When getting a carb from another vehicle, whenever possible, get the factory cable bracket. Even if you're using an aftermarket intake, it might come in handy for making up your own bracket. And regardless if using an aftermarket intake or not, the bracket can be used to measure the correct cable/carb relationship for setting up whatever bracket that's used. The throttle linkage are specific to the manufacturer (GM products including 1971 Ford Mustangs with the 429 Cobra Jet and mid-1980s Mopars have used the Quadrajet). |
| − | *Make note of the engine displacement/engine VIN code. These carbs were used on 4.3L V6 through 7.4L V8 engines, so knowing what it came from gives a leg up on what may potentially need changed. | + | *Make note of the engine displacement/engine VIN code. These carbs were used on 4.3L V6 through 7.4L V8 engines (besides its use with GM products the Quadrajet was found in some obscure applications e.g. 1971 Ford Mustangs with the 429 Cobra Jet and 1983-88 Chrysler vehicles), so knowing what it came from gives a leg up on what may potentially need changed. |
*If the Q-jet is to be used with an automatic transmission that uses a detent (kick down) or TV (throttle valve) cable, be sure the throttle arm is correct (below, right). Many manual transmission-equipped vehicles are missing the lower part of the throttle arm (below, left); this is where the detent/TV cable ordinarily attaches. | *If the Q-jet is to be used with an automatic transmission that uses a detent (kick down) or TV (throttle valve) cable, be sure the throttle arm is correct (below, right). Many manual transmission-equipped vehicles are missing the lower part of the throttle arm (below, left); this is where the detent/TV cable ordinarily attaches. | ||
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=====Soaking the parts===== | =====Soaking the parts===== | ||
{{Caution}}According to [http://www.hotrodders.com Hotrodders] forum member '''''trees''''': | {{Caution}}According to [http://www.hotrodders.com Hotrodders] forum member '''''trees''''': | ||
| − | <blockquote>''"Soaking all metallic parts is the way to go but using small brushes lightly is a good | + | <blockquote>''"Soaking all metallic parts is the way to go but using small brushes lightly is a good idea. Do not soak non-metallic items." ^''</blockquote> |
=====Cleaning with brushes and wires===== | =====Cleaning with brushes and wires===== | ||
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=====Base/throttle plate===== | =====Base/throttle plate===== | ||
| − | {{Note1}}Sometimes the Q-jet base plate may be missing a screw or two (there are only two on most carbs; three at the most). While the base plate is "helped" being held on by the two long front intake manifold mounting bolts and the two long screws at the rear of the carb, it's still a good idea to replace the missing screws. Just be sure to not over tighten these long bolts. If they're over tightened, it can warp the carb permanently. | + | {{Note1}}Sometimes the Q-jet base plate may be missing a screw or two (there are only two on most carbs; three at the most). While the base plate is "helped" being held on by the two long front intake manifold mounting bolts and the two long screws at the rear of the carb, it's still a good idea to replace the missing screws. Just be sure to not over tighten these long bolts. If they're over tightened, it can warp the carb permanently. |
=====Float/fuel bowl===== | =====Float/fuel bowl===== | ||
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| − | Edelbrock has four different PP springs: gold (4"/Hg), orange (5"/Hg), black (6"/Hg), and yellow (8"/Hg) in their p/n | + | Edelbrock has four different PP springs: gold (4"/Hg), orange (5"/Hg), black (6"/Hg), and yellow (8"/Hg) in their p/n 1994 spring kit. These springs are also available in their "Race Calibration Kit" that contains a selection of main jets and rods, secondary rods, hangars, PP springs, high flow needle and seat and an accelerator pump. There are also other suppliers of PP springs and other various tune up and repair parts; see the links below this section. |
*GM power piston spring p/n 7037305 is set for a tip in point of ~6 in/Hg, and would work well with a high vacuum, smooth idling and/or wide LSA type cam. | *GM power piston spring p/n 7037305 is set for a tip in point of ~6 in/Hg, and would work well with a high vacuum, smooth idling and/or wide LSA type cam. | ||
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[[File:CHOKE HOT AIR SEVERAL TYPES.jpg|thumb|300px|left|Several types of hot air choke housings]] | [[File:CHOKE HOT AIR SEVERAL TYPES.jpg|thumb|300px|left|Several types of hot air choke housings]] | ||
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[[Category:Engine]] | [[Category:Engine]] | ||
[[Category:Carburetors]] | [[Category:Carburetors]] | ||
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