Four of the eight firms vying for Montgomery County's coveted cable television franchise are equally qualified, the county's cable consultant said yesterday in his first ranking of the applicants.

Although all four firms were ranked within four percentage points, highest marks were given to Tribune-United Cable of Montgomery.

The firm is a venture of The Tribune Co., publisher of The Chicago Tribune newspaper and United Cable Television Corp., the 11th largest cable company in the country. It is represented locally by Stan Gildenhorn, the county's Democratic Central Committee chairman.

The firm was followed by Montgomery Cable Communications/Times-Mirror Cable Television of Maryland (whose local board chairman is R. Robert Linowes, a prominent lawyer in the county); Tele-Mont Communications; and Viacom Cablevision of Maryland.

The effect of the group endorsement broadens the decision process beyond the usual one or two serious candidates most jurisdictions must evaluate.

Carl Pilnick, owner of the Los Angeles-based Telecommunications Management Corp., was hired by the county in October 1980 and has been paid $47,000 for his services.

The rankings are only the first phase of a complicated selection process that will end with the county executive selecting a franchise agreement this summer, subject to County Council approval. But the report is considered vital in the race to build and operate the county's $100 million cable system.

"This is kind of like football camp," said Jay Beck, franchise director for Tele-Mont. "This is the first cut."

Pilnick, who currently is at work on various phases of cable franchising efforts in Minneapolis, Baltimore and New Orleans, said all four of the top-ranked proposals are excellent and the difference between them is not significant. His group endorsement is consistent with his past reluctance to separate closely ranked firms.

Although county officials yesterday clearly were pleased that they have so many firms from which to choose, the mass ranking muddles the question of who will win the franchise.

"We had hoped that there would be a clear leader," said John Hansman, the county's cable television project manager. "It doesn't make the decision easy, but at least we can make it knowing we're not at risk of picking one not capable of doing the job."

The four remaining firms were ranked, in order: First County Cable (a venture involving Abe Pollin, owner of the Washington Capitals and Bullets), Warner Amex Cable Communications (a joint venture of Warner Communications and American Express), Cablevision of Montgomery County and Montgomery Community.

Reaction from the firms ranged from jubilation to dismay and disinterest. Arthur Barber, president of the Montgomery Community Cablevision, which finished last, was unperturbed. "You'd think that this report was ordained by God," Barber remarked.

A local employe of the front-runner, Tribune-United, danced around the office yesterday, exclaiming, "We're first! We're first!" The report was based on a point system dealing with items such as experience, system design and finances.

Firms with generous promises did not always score highly, as they could be penalized for being unrealistic, Pilnick's report said.

The county's timetable calls for the first customers to have service by next summer, but the firms listed between two years (Montgomery Community) and 54 months (Tribune-United) as the time needed to completely ready the system.

The service will be available to about 95 percent of the county's households (Gaithersburg residents already have a separate system), and about half of the county's households are expected to subscribe.

Tribune United and Tele-Mont won points because their systems would cover the entire county. "This difference requires more plant mileage, and also . . . more rural areas that are difficult to cable," Pilnick said.

The winning firm will pay a franchise fee of 5 percent of its gross revenues in the county, which is expected eventually to amount to more than $1 million a year. That money will pay for the county's regulatory costs and will finance community programming.

Tribune-United, the firm given an edge by Pilnick among the front-runners, said it will cost the company more than $96 million to install its system in Montgomery County. Its proposal includes 108 channels.

The first 42 channels, which would cost residents $1.50 per month, would include all Washington and Baltimore television stations, a children's channel named Nickelodeon and access to a Walt Disney channel and Cinemax, a feature film service.

The next 84 channels would cost residents a minimum of $5.95 monthly and includes New York, Chicago and Atlanta superstations and two all-news stations. Subscribing to this second tier of channels would allow residents access to nine movie stations. A third subscriber option includes all 108 channels and adds computer capability to home television sets at an extra $8.95 per month.

The next phase of the selection begins Tuesday when the County Council confirms a Cable Review Panel that eventually will oversee the selection process and will recommend its top-rated firms to County Executive Charles W. Gilchrist.

Each firm now has 15 days to respond to Pilnick's report. Pilnick will meet with the Cable Television Advisory Council, another citizens' review panel, on May 11. Public hearings will be held May 24-27 and each firm will be given an hour to present its case.

Hansman, the county's cable coordinator, is to rank the firms by July. Gilchrist's final selection, and the council's vote, will follow.