From the Parts Counter

The Short Answer Spreadbore and Squarebore are terms used to describe the 2 major designs of 4-barrel carburetors.  In a spreadbore design, the primary bores are smaller than the secondary bores.  In a squarebore design, both the primary and secondary bores are the same size.   Fig 1: Squarebore vs spreadbore The Longer Answer The bores (also known as barrels) are parallel chambers going from the top of the carburetor body to the bottom (base) of the carburetor body.  They are the chambers where fuel and air are mixed together to create the combustion charge that makes the engine run.  ...

The Varajet II was a 2 barrel carburetor optimized for 4 and 6 cylinder engines, and was installed in cars and trucks from 1979 through 1986.  The Varajet II featured a progressive linkage, where increasing throttle position opened the 2nd barrel, increasing airflow to the engine.  This article explains the differences between the two variants of Varajet II carburetors: The 2SE and the E2SE, how to tell them apart, and how to figure out which one you need.

The engine that won't die. Cars equipped with carburetors can suffer "dieseling" or "run-on".  This is more common when using unleaded fuel, but can happen with leaded fuel as well.   Dieseling is when after the ignition is shut off (causing the spark plugs stop firing), the engine continues to try to run.  Perhaps you're familiar with the symptom- you turn off the engine and it starts coughing, bucking and clanking, sometimes for up to 30 seconds.   Aside from being embarrassing, repeated occurrences of dieseling can actually damage your engine. What causes dieseling? When the ignition is turned off, the spark...

You have choices when purchasing auto parts, but what you don't know may hurt you.  The best parts for your vehicle are the ones it came with, if they're available.  If they are not, educate yourself on what's available and make an informed choice.