Wente and Concannon: the names must be familiar,

but what image do you have of them? Conservative,

reliable, but perhaps a little dull? Well, you should

see how the conservatives are celebrating their birth day. The fun and games started in April in Livermore, Calif. and continue through the summer: wine festivals, balloon rides, a turn-of-the-century costume ball, dinners galore, breakfasts in the vineyards. This is no ordinary birthday. It is a joint celebration of the centennials of the two California neighbors.

In 1883, Carl H. Wente was a German immigrant who'd developed a fondness for winemaking. James Concannon was an Irishman who bought his first vine cuttings from Ch.ateau d'Yquem. They planted their vineyards in the gravelly soils of the Livermore Valley, east of San Francisco. The vines and the two families thrived.

Today Wente Brothers is still a family-operated business, run by Carl H.'s great-grandchildren, Eric, Philip and Carolyn. Jim Concannon, grandson of the first James, sold his winery in 1978, remaining its president. It was resold in March this year to Distillers Co. Ltd., a Scottish-American group (Gordon's, Johnnie Walker, Dewars, Haig). With Jim continuing as president and Sergio Traverso, a skilled and level- headed oenologist, as winemaker, the new owners won't change their new acquisition except to develop its sound financial base.

Wente is by far the larger of the two wineries, with extensive vineyards in Livermore and in Monterey County. Having built up a range of white wines in the '50s and '60s, the Wente family enjoyed the white boom of the '70s. And then they moved ahead to a new venture: a sparkling, champagne method wine.

They purchased the old Cresta Blanca winery, another Livermore pioneer. It is being converted into a champagne cellar with a capacity for 35,000 cases. The grapes for the sparkling wine, chardonnay, pinot noir and pinot blanc, come from the cooler Monterey vineyards. After the second fermentation, the wine is given two years on the yeasts and is then riddled by hand. Timed to coincide with the centennial, the first release is the Wente '80 Brut, $12.00: a clean, refreshing wine, with a strong bead.

Over the road at Concannon, Traverso is blending its two established white varieties, sauvignon blanc and semillon, to develop a wine that downplays the pronounced grassiness of nose and taste often associated with California sauvignons. The '81 Sauvignon Blanc Estate, $9.50, is almost half semillon. Traverso has kept the acidity high, and with a few years of bottle age, it will soften into a balanced, subtle, dry wine for the dinner table. The proportions in the blend will change in future vintages to comply with labeling regulations that require a varietally labeled wine to contain a minimum of 75 percent of that variety. Despite the change, '81 is still a forerunner of the understated Concannon style.

Wente and Concannon are neither conservative nor dull. With the confidence of a century of winemaking, they have a more balanced attitude than many of their younger and more excitable competitors. They've weathered the dry and wet patches of America in the past hundred years --and they intend to weather the next hundred. Let's drink to that.