Carlisle left it late to preserve their unbeaten run but the draw was the fair result, on balance of play, at the end of another nail-biting day.
United were on the hunt within 60 seconds of kick off and a ball into the edge of the box from Jones was nodded down by Raynes. Shaun Miller was onto it in a flash but his snapshot was deflected over the bar by Parkes.
Carlisle stayed forward and a long throw from Tom Miller caused confusion as Raynes headed it down. Mark Ellis was alive to the touch and he was disappointed to see his volley on the twist smash into the side netting.
Orient were gifted an opening at the other end when a roll-out from Gillespie put Gillesphey under pressure. McCallum nicked it but the keeper made amends with a good save at his near post.
Defender Mark Ellis found himself in a shooting position as Orient messed about with the ball in midfield but Cisak was well placed to gather it up as it came at him at chest height.
More set piece problems followed for the O's when Grainger sent one long and another scuffed clearance presented Devitt with a clear sight of the target. He wrapped his boot round it but the connection was poor and it whisked well wide.
Attempts from Bowery and Massey came in from distance as the teams battled for supremacy, but it was Carlisle who looked the more likely as they attacked in numbers. More sustained pressure brought a toe poke from Raynes which hit a defender and bent wide.
The resulting corner was flicked on by Ellis and it eventually squeezed free for Raynes, who had positioned himself on the edge of the area. More brave defending prevented what looked a certain goal.
Another Tom Miller long throw was headed high and backward by Bowery and Shaun Miller did everything right as he trapped it and readjusted for the volley. There were two many bodies in the way for him to find a way through.
Chance after chance followed and United thought they'd broken the deadlock when Adams opened himself up just inside the box. He dinked, dropped a shoulder and curled a beauty round his marker, but Cisak was saved by the base of his post.
Shaun Miller drilled an awkward bounce right at the O's stopper when it came off Weir and sat up nicely, and he was a hair's breadth away from getting a touch on a lovely cross from Devitt as the tempo remained high.
A well-worked move from the visitors put McCallum clean through just before the break but Gillespie raced off his line to close the angles and make the block.
But it proved to be an unheeded warning as a similar situation led to the opening goal of the game, when a shove on Devitt went unnoticed by the officials deep inside the home half. McCallum spun off his man and he matched the quality of the through ball with a crisp finish which left Gillespie with no chance.
It took just 26 seconds of the second half for United to pull level and it was substitute Charlie Wyke who made an immediate impact when he touched a ball over the top out wide for Shaun Miller to chase. He slowed things down then delivered a killer ball which left the big forward with the simple task of touching his fourth of the season into the waiting net.
A wonder save was needed from Cisak from a crunched drive from Adams to prevent a second goal for United in the very next attack, and that lifted the visitors and brought them out of their shells. Their approach play had purpose but Palmer and Weir were wayward when they sniffed at openings.
Another neat through ball from Shaun Miller put Wyke and Cisak in a race for a touch and it was the striker who got there first to go past his man. Two challenges slid in and the referee showed no interest when the forward tumbled to the floor.
The home side incresased the pace of their passing and that allowed Lambe to send one to the back stick. Raynes got plenty of power on his header but it spun off the slick surface and fell wide of the target.
A lapse of concentration allowed Orient to regain the lead when Joyce was left to face Cornick as he ran into the final third in full flight. The wide man made easy pickings as he forged his way into the area and Gillespie could do nothing as the ball was crashed into his bottom corner.
Carlisle were ruffled and Cornick tried his luck again when he cut inside and let a shot fly. It skipped off Raynes and dropped just over the bar.
Defender Tom Miller screwed a difficult volley over the bar when he had time on his hands, and Ibehre popped a header from a Grainger cross wide as United tried to gain some momentum, and there was more in the way of territory and possession for the hosts as the visitors sat deep.
Wyke put a Tom Miller cross into the side netting as the clock ticked down, and the Cumbrians were awarded a penalty when Lambe latched onto a pass from Jones. His cross was stopped in flight by Kelly, with a hand, and captain Danny Grainger kept his cool to thump it in from 12 yards.
Carlisle United - Wyke (46), Grainger (87 pen)
Leyton Orient - McCallum (44), Cornick (64)
Carlisle United - Raynes (73), Ibehre (87)
Leyton Orient - Kelly (51), C Kennedy (56), Weir (90)
Carlisle United - Gillespie, T Miller, Raynes, Ellis (Wyke 46), Gillesphey, Grainger, Joyce, Jones, Adams, Devitt (Lambe 46), S Miller (Ibehre 69). Subs - Crocombe, Atkinson, J Kennedy, Brough.
Leyton Orient - Cisak, C Kennedy, Kelly, Parkes, Weir, McCallum (Semedo 78), Massey, Hunt, Cornick, Bowery (Palmer 51), Erichot. Subs - Sargeant, Nnomo, Pollock, Judd, Ochieng.
Referee - Mr Ben Toner
Attendance - 4,465 (236 away fans)