Political action committees gave a record $104 million to congressional candidates in the 1984 elections, with House Democrats among the leading beneficiaries, according to a report released yesterday.

Incumbents fared better than ever, receiving 73 percent of the PAC money. That compares with 66 percent that was funneled to incumbents during the 1982 campaigns and 61 percent in 1980.

Total PAC contributions rose by 25 percent in the 1983-84 cycle, according to the study by Public Citizen's Congress Watch, a Ralph Nader organization.

In the 1981-82 cycle, PACs gave $83.6 million.

Democrats continued to increase their share of the special-interest money, collecting 58 percent during the 1984 campaign, compared to 54 percent two years ago and 52 percent four years ago.

The increased role of special-interest money in financing congressional campaigns was most evident in the number of House and Senate candidates who received substantial PAC contributions.

Two Senate candidates -- Rep. Phil Gramm (R-Tex.) and Sen. Charles H. Percy (R-Ill.) -- received more than $1 million apiece from PACs. Gramm won his Senate race, while Percy was defeated by Rep. Paul Simon (D-Ill.).

Eleven other Senate candidates received more than $800,000 in PAC funds. In the 1979-80 election cycle, no Senate candidate received more than $800,000.

In the House, 95 candidates received more than $200,000 in special-interest money, led by Rep. James R. Jones (D-Okla.), with $694,212. In the 1980 elections, only four House candidates received more than $200,000, while two years ago 30 candidates received that much.

Of the top 25 PAC recipients in the House, 21 were Democrats, the study found. After Jones, the leading PAC beneficiares in the House were Reps. Jerry M. Patterson (D-Calif.) with $435,875, Gerry E. Sikorski (D-Minn.) with $419,147, Bruce A. Morrison (D-Conn.) with $407,779, and Les AuCoin (D-Ore.) with $400,766.

Patterson was defeated for reelection by former House member Robert K. Dornan (R-Calif.). Morrison and Sikorski, freshman Democrats thought to be in difficult races, both won reelection.

House Minority Leader Robert H. Michel (R-Ill.) was the leading Republican PAC recipient, with $388,329. Second was Rep. Jack Fields (R-Tex.), with $361,342.

The Congress Watch study also found that 12 House incumbents with little or no opposition received more than $200,000 from PACs. Of the 12, eight are on the House Ways and Means Committee, where tax legislation originates.

Tops among this group was Rep. Dan Rostenkowski (D-Ill.), the Ways and Means chairman, with $295,505, followed by Rep. Richard A. Gephardt (D-Mo.), $245,660.

The National Association of Realtors and the American Medical Association both gave more than $2 million to congressional candidates.