Carlisle struck twice to grab a deserved three points following another excellent away display of dogged defending whilst hitting back with purpose on the break.
United utilised a clever kick off routine to take the ball from left to right and back to front as almost every player touched the ball in the opening 30 seconds of the game. Grainger overlapped on the left and his low cross was deflected behind for a corner which the O's comfortably cleared.
Orient responded with a good move down the Carlisle right and hesitation from Raynes allowed Pritchard to get behind the back line. He tried to squeeze his shot in from a tight angle but he got his bearings wrong and he dragged it into the advertising hoardings.
A long ball into the Carlisle area brought a half clearance which Moore was quick to spot. His volley from 22-yards had to be dealt with as Gillespie went full length to beat it away.
The home side kept the pressure on and Clohessy did well to make space for a cross. The Blues keeper was off his line quickly to gather it in.
Having soaked up the early pressure Carlisle got forward and a slide rule pass from Kennedy took Asamoah out wide. He was dragged back as he beat his man tight by the corner flag and Grainger trotted over to take charge of the free kick. He almost caught Cisak unawares as he went for the roof of the net with a fierce drive. The big stopper readjusted to thump it away.
United were let off the hook on 19 minutes when Shaw sent a lovely cross at the penalty spot. Palmer got in front of his man but his left foot volley, from very close range, lacked any kind of power and Gillespie was able to make the save.
Clohessy looked like the man to be watched and he broke away to send another cross into the mix. Raynes cleared it and Payne was disappointed when he dragged his first time shot well wide as he took it on the full.
Raynes wasn't too far away when he nodded another Grainger free kick just wide at the other end and that was followed by a good spell of visiting pressure as Miller, McQueen and Sweeney put deliveries into dangerous areas.
Orient bit back with a lightning quick break as Clohessy was left in acres of space. His early cross was nodded back into the mix by Payne and Raynes had to time his sliding tackle to stop Simpson from tapping it in.
The action flowed back the other way and Asamoah fizzed one into the stands when he found a yard. That was followed by neat passing from Grainger, Sweeney and Kennedy which left McQueen unmarked. His curling pass was tipped behind as Asamoah raced in.
Joyce got an important touch to stop Simpson from applying any kind of meaningful finish to a cross from Shaw and the same man covered again when Clohessy pulled one back from the byline as he looked up to see players lined up in the box.
The United goal lived a charmed life on the stroke of half time when a clearance from Raynes fell invitingly for Cox. He set himself and his 35-yard dipper smashed off the top of the bar as Gillespie looked on in anguish.
And the hosts were close again when Simpson spun on the ball on the edge of the area. He caught it well but he couldn't keep it down and it flew over the target.
Cox smacked the ball against the bar for the second time on the night just two minutes into the second half when he whipped a 35-yard free kick over the wall. Gillespie scrambled to get there but he wasn't needed as it hit the woodwork and spooned into the night sky.
Moore was next to go close when he took a pass on the run from Simpson. He had to go for guidance rather than power and his grass cutter bobbled an inch past the upright. Orient quickly got back on the front foot and Moore picked out Palmer in the box. A lovely header beat the keeper but it connected with the inside of the post and bounced nicely for Gillespie to turn and gather.
A long winding run from Clohessy brought another cross for Palmer to battle for but the close attentions of Raynes were enough to put him off.
It was Carlisle who struck a real blow just past the hour when Dicker split the defence with the pass of the night. Derek Asamoah didn't need to be asked twice and he left Cisak with no chance as he drilled it into the bottom corner.
But the lead lasted less than two minutes as Orient won a corner from the restart. Captain Mathieu Baudry came from deep and Gillespie had no chance as a crunching header rattled the back of his net.
United boss Keith Curle was sent to the stands with 20 minutes left to play, following an altercation with Andy Hessenthaler, but his side regained the lead from their next attack when Grainger bided his time for a cross. Sweeney took a swipe and he reacted first to the block with an unstoppable scissor kick.
Raynes blocked from Simpson as Orient tried to reply for a second time, and Payne miscued and shot high as he shot early from another half clearance.
Carlisle showed fantastic game management, and had a horrible miss from Turgott to thank into the bargain, as they saw it out for a hard-earned and deserved three points.
Orient - Baudry (64)
United - Asamoah (62), Sweeney (73)
Orient - Shaw (25)
Leyton Orient - Cisak, Clohessy, Baudry, Essam, Shaw (Kashket 86), Payne, Pritchard, Moore (Turgott 75), Cox, Palmer, Simpson. Subs - C Grainger, Dunne, James, Moncur, Agyemang.
Carlisle United - Gillespie, Miller, Raynes, Gillesphey, McQueen, Dicker, Joyce, D Grainger, Kennedy (Archibald-Henville 90), Sweeney (Atkinson 89), Asamoah (Gilliead 87). Subs - Hanford, Hery, Balanta, Osei.
Referee - Mr Charles Breakspear
Attendance - 4,408 (284 away fans)