Congress finally gave President Carter standby power to impose gas rationing yesterday, as the House approved a rationing bill 301 to 112.

The Senate passed the bill last weel, 77 to 13.

The legislation enables the president to draw up a rationing plan that could be put into effect only if gasoline supplies were cut substantially, and then only subject to further congressional approval.

Though this final approval came easily, rationing has been bitterly fought over all year.

The first round came in May when, as required by then-existing law, the president submitted a detailed rationing plan and it was shot down by the House. That was a gas-line month. The plan was beaten by members who feared their constituents or the leading economic interests in their districts would be left without enough gasoline.

In late summer House leaders tried again, with a bill to let the president draw up a plan and hold it in reserve without congressional involvement. Congress would only have a say when he moved to put it in effect. The House balked once, then bought that approach.

However, when the bill went to House-Senate conference, senators demanded some say for Congress in drawing up the plan as well.

The conference report approved yesterday does provide such a say, but ultimately it would require a two-thirds vote of both houses to reject a rationing plan.

Floor leader John D. Dingell (D-Mich.) said the bill's easy passage yesterday could be attributed partly to the compromise on congressional approval, and also to concern over possible oil production cutbacks "any minute" by Iran, Kuwait or Saudi Arabia.

"The need is becoming increasingly clear to prepare ourselves for major interruptions in the oil supply," Dingell said. Republicans who had overwhelmingly voted against rationing earlier provided 71 votes in favor of the bill yesterday.

The rationing section of the bill would require the president to submit a plan that would distribute a shortage equally among the states, while taking into account the differing needs of various end users. There is no deadline for presidential submission of a plan, but the administration would have to report periodically on its progress in drawing one up.

When the rationing plan is submitted to Congress it will be considered approved unless both houses pass resolutions of disapproval within 30 days. The president could then veto the disapproval within 30 days. The president could then veto the disapproval resolution, and it would take a two-thirds vote by both houses to override his veto.

Once the plan is approved it would sit on the shelf until needed. If there were 20 percent shortage of motor fuel that would last for 30 days, the president could implement rationing, subject to a one-house veto. If the shortfall were less than that, the president would need approval of both houses to impose rationing.

The bill also would give the president and states authority to draw up conservation plans to make savings for any fuel in short supply.

The president would be required to establish state-by-state fuel-saving targets for the fuel in short supply. The state would then submit plans to meet the target to the secretary of energy.

If the state plan has been operating for 90 days and isn't meeting the targets and an 8 percent shortage of the fuel is likely to exist for 60 days, a federal conservation plan could be imposed on the state. If a state has no plan approved by the energy secretary the federal plan could be imposed even if the shortage isn't 8 percent.

All area congressmen voted for the bill.