The two sides had been level for most of the match, a try from Bridgend replacement Jac Hopkins bringing the sides level with 10 minutes to go. A 50 metre penalty from fellow substitute Lewis Williams then looked to have won it for the Ravens with just seconds remaining on the clock.
But with victory insight, Bridgend lost it at the death. Pontypridd turned down a chance to kick at goal and were rewarded with victory when Dacey ploughed through some tired tackles for the winning score.
The first half had ended with the two sides level at 13-13. Tom Grabham crossed for the first try of the day as the Ravens moved into a 10-0 lead before Tom Hetherington got Pontypridd back into it. Jack Dixon and Dai Flanagan had kicked the rest of the points in a tight opening 40 minutes.
The second half was equally close, a penalty try seeing Pontypridd reclaim the lead. The Ravens refused to go away though and looked to have deservedly won the game before Dacey had the final say.
A young Pontypridd side had been shocked in the first few minutes as Bridgend moved into a clear lead. Dixon had kicked an early penalty before wing Grabham made the most of an error by Pontypridd full back Aled Summerhill. The Wales Under 18 international saw his attempted clearance kick charged down leaving Grabham to pick up and easily jog the 15 yards for the try. Dixon converted to complete a dream start for the Ravens.
Bridgend's superb first 10 minutes only served to infuriate Pontypridd though and the home side soon responded. Flanagan got things moving with a penalty before Hetherington finished off a superb team move after Gareth Wyatt had chipped ahead. Flanagan added the extra two and after 25 minutes, the sides were back at level pegging.
After a slow start, Pontypridd were now on top and as usual, they were creating plenty of chances. But initially, further tries failed to arrive with the home side's backs guilty of butchering at least one golden opportunity.
And the longer the game stayed level, the more encouragement Bridgend seemed to take. The Ravens' backs looked dangerous when given the chance to attack, Grabham especially lively. Dixon then put his side back into the lead though Flanagan replied with the last kick of the half to send the sides in level.
The start of the second half saw Pontypridd move into the lead for the first time courtesy of a penalty try. There was some confusion surrounding the score, Summerhill going close in the left corner and when play was stopped, referee Ian Davies ran under the posts. Whatever the reason for the score, Davies seemed to hold Dixon responsible, the Bridgend fly half yellow carded after the try was awarded.
Flanagan converted but although they were a man light, Bridgend refused to cave in. Arthur Ellis was at the heart of their forward effort, the Ospreys man carrying effectively on a number of occasions. Dixon failed to return when his spell in the bin was up, Lewis Williams his replacement, and with the game entering its final quarter, the Ravens were the ones on top.
It was full-blooded stuff with Bridgend more than holding their own. Both sides had chances but in the 68th minute, Bridgend were given a chance when Flanagan was yellow carded for slowing the ball down illegally.
With his fly half in the bin, McIntosh sacrificed centre Gary Williams for Simon Humberstone as he attempted to keep some control on the game. But with 14 men, it was always going to be difficult, especially with Bridgend seeing so much ball.
Wave after wave of attack pounded the Pontypridd line, the pressure rewarded when Lewis Williams set up Hopkins for Bridgend's second try. The conversion made it 20-20 but it was the visitors who were dominating.
And a couple of minutes from time, Bridgend won a penalty on the halfway line. Lewis Williams stepped up to nervelessly slot over the kick and that looked to be that.
But from the restart, Bridgend knocked on and after some sustained pressure, Dacey broke the Ravens' hearts. Flanagan's conversion merely added salt to an already gaping wound.
Tries: Hetherington, Penalty, Dacey; Conversions: Flanagan (3); Penalties: Flanagan (2).
Tries: Grabham, Hopkins; Coversions: Dixon, Williams; Penalties: Dixon (2), Williams.