Former Lt. Gov. Henry Howell disclosed today that he plans to borrow $20,000 for a minimal last ditch television effort on behalf of his campaign for the Democratic nomination for the Virginia governorship.

While campaigning through South-west Virginia on a two-day swing that took him close to the western-most tip of the state. Howell said he had arranged to borrow the money Tuesday from a Norfolk bank using as security some Chesterfield County municipal bonds he owns.

"I've already got $10,000 of my own money into this campaign," Howel said. This will just be more of the same."

Howell, who once likened the underbuying of political television time to "dropping butter bean in a bathtub" said today "we're really just dropping one butter bean in the whole Atlantic Ocean" with the planned TV effort.

He said his advisers had told him that his race against former Attorney General Andrew P. Miller in next Tuesday's Democratic primary was so close that "we ought to get on TV . . . If only to rouse up the troos.

He said he had contracted with Washington based television producer Gerald Rafshoon, to have the $20,000 check in Rafshoon's office by noon Tuesday. Howell had earlier paid Rafshoon $30,000 to produce seven television commercials that the campaign has until now been too impoverished to air.

The Rafshoon commercials, Howell said, had originaly been planned as part of a $200,000 radio and TV campaign beginning May 15.

Howell said today, "that was just a dream sheel."

The current campaign, he said, will air spots beginning Thursday in Northern Virginia, Roanake and three stations in Howell's home area of Hampton Roads.THowell said the $30,000 he personally will put into the campaign is a new departure in his three campaigns for the governorship, which previously been entirely financed by contributions. "In 1973, I paid the filing fee (of about $1,000 and that was about it," he said. "This year it's a different deal."

The Howell campaign has been plagued with money problems almost from the beginning.

In another campaign development, Jack Carter, son of President Jimmy Carter, began unannounced campaign swing through the state today in support of Howell, the Associated Press reported. He said his decision to come to the state was because of his "personal support" of Howell.

Campaigning in Abingdon, Carter was asked whether the move had the President's support. "Frankly I didn't ask him," Carter replied, according to the AP.