A vacuum advance is not really an original part of your car but an optional device to improve the timing in your internal combustion engine. This device provides a spark timing that is proportional to the speed and load of your car. In short, if you have a vacuum advance in your distributor, your car will have a better speed in relation to whatever amount of load it carries. If you are driving an ordinary vehicle (meaning not race cars and heavy-duty trucks), you will experience improved drivability, fuel economy, and idle quality once you install a vacuum advance.
Understanding the specs
There are a few words you need to add in your vocabulary if you are looking to install a vacuum advance on your car: part number, ID, Hg level, and max advance. Make sure that you match the label or part number written on the product with the engine number of your car. This applies to all kinds of stock parts you are going to install in the future. There is also a coded ID number for you to recognize the manufacturer and the brand. For you to get the right vacuum advance, you must know the three-digit Hg (mercury) level of the device. In a set like 5-12-8, the first number indicates the inch of mercury when the vacuum advance starts, while the second number is the inch of mercury when the device ends. The third number, the max advance, is the total advance or proficiency provided by the product. Knowing this spec, you should only buy a vacuum advance with a higher Hg level if you have a heavier engine. The heavier the engine, the more the vacuum works harder.
Understanding price, quality, and store
Buying a vacuum advance for your car can be tricky because not all online auto parts stores list them. Some may just tell you that they will order the unit, but you will only end up waiting. Make sure that you check out online stores that really have a huge stock of the product. Compare prices from various stores in order to get the best deal. Remember that an expensive unit does not always guarantee quality. If you find yourself buying a pricey one, make sure that there is a return policy to safeguard your purchase.