Ethyl Corp. reported record sales and profits during 1978 despite a second-quarter settlement of a long tax dispute with the Internal Revenue Service, which cost the Richmond company $3.5 million.

The diversified petroleum and industrial chemicals firm said yesterday that earnings for the year rose 6 percent to $82.7 million ($4.02 a share) from $78 million ($3.75) as sales jumped 11 percent to $1.4 billion.

In the fourth quarter, Ethyl profits were $20.5 million (99 cents) vs. $17.6 million (86 cents) and sales soared 19 percent to $379 million, also a record.

The IRS dispute involved allocations of prices paid in a 1962 acquisition and reduced earnings by 18 cents a share.

McCormick & Co., a Maryland food and spice firm, reported that annual sales topped $400 million for the first time in the year ended Nov. 30, with profits up 13 percent to $16.7 million ($1.48 a share) compared with $14.8 million ($1.35) the previous year.

In the fourth quarter, McCormick earned a record $9 million (80 cents), up 45 percent from $6.2 million (55 cents) in the 1977 period as sales rose 12 percent to $127 million.

Comten Inc, a manufacturer of communications computer systems with major operations in Rockville, said operating earnings for 1978 would be about $4.2-$4.4 million (between 78 cents and 82 cents a share) compared with $2.4 million (47 cents) a year ago. Sales rose to $53 million from $36.2 million.

The projected results were released in conjunction with an announcement that NCR Corp. has agreed to buy Comten for about $125 million in a takeover offer of $22 a share for up to 45 percent of Comten stock and an exchange of shares.

In Dayton, NCR said yesterday its offer for up to 2.4 million of Comten shares will expire at 5 p.m. on Feb. 2. Comten's board has recommended that owners desiring to receive cash should accept the NCR offer.

First Financial of Virginia Corp., a savings and loan holding company in McLean for Washington-Lee S&L, reported record profits in the six months ended Dec. 31. Earnings were $1.16 million ($2.44 a share) compared with $1 million ($2.11) a year ago, a gain of 16 percent. Directors also approved a semiannual dividend of 25 cents a share, payable Jan. 31 to owners of record Jan. 15.

Washington-Lee S&L assets rose 14 percent in the recent six months to a record $319 million while mortgage loan volume increased 27 percent to $55 million for the six months.

Commonwealth Banks Inc., a new Richmond holding company, reported 1978 profits of $13.05 million ($2.61 a share) compared with $10.3 million ($2.10) for its member banks in 1977, not counting securities transactions. The firm was formed Dec. 31 in a merger of Central National Corp. and Fidelity American Bankshares.

Total resources of the new holding company were $1.7 billion on Dec. 31, up 15 percent in the year, while statewide deposits increased 11 percent to $1.4 billion.