Two Northern Virginia political leaders yesterday defended the big emergency gasoline allocation the region received from the state during July.

"We have never gotton more than our fair share," said Fairfax County board chairman John F. Herrity in answer to Tidewater critics led by Portsmouth Mayor Richard J. Davis.

Herrity and Del. Vincent J. Callahan (R-Fairfax) said the criticism of the increased allocation, which came after repeated pressure on Gov. John +N. Dalton by Northern Virginia leaders, was simply "regional politics."

During July, Northern Virginia got 40 percent of what is called the state setaside (5 percent of total allocations of gasoline to the state), which can be used by the governor to deal with hardships wherever they occur. In June, Northern Virginia got only 32.6 percent of the setaside, when it represented only 3 percent of the total allocations.

Herrity, a Republican, said "I question whether we got our fair share in July even with the 40 percent setaside allocation.

He said Northern Virginia has 24 percent of all vehicle registrations in the state and accounts for 19 percent of the traffic on interstate and primary roads and 28 percent of the traffic on secondary roads.

Callahan, noting that Portsmouth's Mayor Davis is chairman of the state Democratic Party, said the mayor's remarks "typify downstate Democratic disdain for our region of Virginia." CAPTION: Chart, Weekend Gasoline Guide