Your PMS Gas Check Kit is designed to check the specific gravity (density) of gasoline.  Gasoline containing a higher density or specific gravity reading will contain proportionately higher energy content.  A density that is too high may also cause uneven fuel distribution and engine deposits.  NHRA allows a specific gravity of .700 to .750.  In a good pump, gas should check in between .733 to .738.  It’s a good idea to buy gas from a station that turns a large volume so as to lessen the chances of getting stale or contaminated gas.  Also, avoid buying gas in cold climate regions, as the gas in these areas may contain low-molecular-weight hydrocarbons.  Although gas with low-molecular-weight hydrocarbons aid in quick starts, it can also cause vapor locks in a hot engine compartment.

Finally, keep in mind that density varies with temperature and your hydrometer is ONLY accurate when used at its calibrated temperature which is 60 degrees F.  Note:  Check this on the bottom of the hydrometer stem – it is VERY IMPORTANT THAT YOU USE THE THERMOMETER.

Procedure:  

1. Fill graduated cylinder with gasoline to the 50 ml. line.
2. Insert thermometer and check temperature.  Note: Don’t let the gas temperature vary more than 2 degrees on either side of 60 degrees F (58 – 62 degrees).  Also, if you are using additives, BE SURE and let the temperature stabilize at 60 degrees F (plus or minus 2 degrees) before checking the specific gravity.
3. CAREFULLY place hydrometer into the cylinder and read the specific gravity directly from the scale on the stem of the hydrometer.  If the hydrometer sticks to the cylinder wall, it may be necessary to slowly spin the hydrometer while taking a reading.

Alcohol Test:  

1. Fill beaker as per gas instructions.
2. Take the temperature of the alcohol in the beaker.  Note:  The reading on the hydrometer should not vary from chart reading below by more than .002 or the alcohol in impure.

      Temperature of Alcohol                                       Hydrometer Reading

                        45                                                                                .803

                        50                                                                                .801

                        55                                                                                .798

                        60                                                                                .796

              Ideal Temp                                                      Ideal Checking Temp

                        65                                                                                .794

                        70                                                                                .792

                        75                                                                                .788

                        80                                                                                .785

                        85                                                                                .782

                        90                                                                                .778

                        95                                                                                .775                

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