Quadrajet

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Quadrajet carburetors were also built under contract by [[Carter]].  This seems to have happened at times when Rochester's facility could not keep up with demand.  Carter-built Quadrajets will have the name "Carter" cast into them, but are functionally identical to the Rochester-built equivalent.  The "newest" Q-Jets were built for, and sold by [[Edelbrock]].  There were several versions made, for both stock replacement and "performance" applications.  One version was specifically intended as a replacement for Carter Thermoquad carburetors.  The Edelbrock Q-Jets have been discontinued, although at this time Edelbrock still supplies some replacement parts.
 
Quadrajet carburetors were also built under contract by [[Carter]].  This seems to have happened at times when Rochester's facility could not keep up with demand.  Carter-built Quadrajets will have the name "Carter" cast into them, but are functionally identical to the Rochester-built equivalent.  The "newest" Q-Jets were built for, and sold by [[Edelbrock]].  There were several versions made, for both stock replacement and "performance" applications.  One version was specifically intended as a replacement for Carter Thermoquad carburetors.  The Edelbrock Q-Jets have been discontinued, although at this time Edelbrock still supplies some replacement parts.
  
You need to pay attention to a few important things when choosing a carb to rebuild/use on your engine:
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'''So, all Q-jets are the same, right?'''  
 
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• Fuel inlet (straight or 90º), so it doesn't interfere w/any of the accessories or water neck, etc.
+
 
+
• Throttle arm- whether or not it can accommodate the trans you're using. This is important if using a TH350 that needs a "below-the-shaft" hook up point to pull the detent cable.
+
 
+
• Choke type. Most prefer an electric. A hot air type choke can be converted to electric easily.
+
 
+
Beyond that, you basically just work w/what you have. The Q-jet is very versatile and will work fine on any number of engines.
+
 
+
1976-up carbs are often preferred due to less wear than the older carbs, often an electric choke will be used, the float and needle and seat assembly set up is better. Also because there were improvements made throughout the run of Q-jets, newer is better. The '76-up carbs will also have APT (adjustable part throttle, a way to fine tune).
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Interestingly, one of the best/easiest way to find a good carb to use is to look for one off of a truck or van. Up until '86, these truck carbs were still non feedback (not an "electronic" carb) in some applications and they were nearly all 800 cfm units- even those found on 4.3L V6 engines! These engines can also have the large coil-in-cap, non-feedback HEI distributors.
+
 
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Cars from '81-up are going to have feedback carbs. No good for anything other than computer use (CCC), or possibly as an all-out race carb where it is set up to run w/o primary metering rods.
+
 
+
So, all Q-jets are the same, right?   
+
  
 
Not hardly! These are a few differences off the top of my head. In no way are these '''all''' the differences:
 
Not hardly! These are a few differences off the top of my head. In no way are these '''all''' the differences:
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There are two different length primary rods, there are stepped and tapered rods.
 
There are two different length primary rods, there are stepped and tapered rods.
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 +
===Choosing a Carb===
 +
----
 +
 +
You need to pay attention to a few important things when choosing a carb to rebuild/use on your engine:
 +
 +
• Fuel inlet (straight or 90º), so it doesn't interfere w/any of the accessories or water neck, etc.
 +
 +
• Throttle arm- whether or not it can accommodate the trans you're using. This is important if using a TH350 that needs a "below-the-shaft" hook up point to pull the detent cable.
 +
 +
• Choke type. Most prefer an electric. A hot air type choke can be converted to electric easily.
 +
 +
Beyond that, you basically just work w/what you have. The Q-jet is very versatile and will work fine on any number of engines.
 +
 +
1976-up carbs are often preferred due to less wear than the older carbs, often an electric choke will be used, the float and needle and seat assembly set up is better. Also because there were improvements made throughout the run of Q-jets, newer is better. The '76-up carbs will also have APT (adjustable part throttle, a way to fine tune).
 +
 +
Interestingly, one of the best/easiest way to find a good carb to use is to look for one off of a truck or van. Up until '86, these truck carbs were still non feedback (not an "electronic" carb) in some applications and they were nearly all 800 cfm units- even those found on 4.3L V6 engines! These engines can also have the large coil-in-cap, non-feedback HEI distributors.
 +
 +
Cars from '81-up are going to have feedback carbs. No good for anything other than computer use (CCC), or possibly as an all-out race carb where it is set up to run w/o primary metering rods.
 +
 +
  
 
==References==
 
==References==

Revision as of 04:17, 7 October 2011

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