Blackwell, fighting in his final amateur bout before turning professional, tangled with Manning in the 125-pound open class event.
Blackwell finished strong in the final two rounds to outscore Manning, who had a running style, in front of a crowd of 300 people.
After an exchange at the ropes in the third round, Blackwell, 25, forced a standing eight count against Manning right at the end of the stanza. In the fourth round, the southpaw used left-right combinations to the head and body and ducked under some of Manning's punches.
"It was a really close fight," Blackwell said. "He (Manning) was a good kid. I just wasn't fully on tonight. It took a while for me to get started. The first round and a half he won. I won the third and fourth rounds. Luckily, my trainers knew what I needed to do. Either he got tired or I was stronger. I pushed a little bit more, I guess."
Blackwell thought Manning landed some punches that solid, but he countered with shots that dazed his foe. Blackwell had to go away from the conventional jab to deal with Manning's style.
"It was my determination to win the fight and stay in there," Blackwell said.
In a four-round battle in the 125-pound open class, Phoenixville PAL's Ryan Carson dropped a close verdict to left-hander Louis Esquilin of Frazier's Gym.
Esquilin had a dancing style that helped prevent Carson from landing enough hard combinations to the body and head. There was a flurry at the ropes in the fourth period.
Phoenixville PAL's Mike Molina won a three-round decision over Bryan Davis of William Hicks Anderson in the 155-pound Junior Olympic class. Molina scored with body shots then two rights to the head in the first period. Molina continued the pursuit to the body in the second period and followed it up with a hard left hook. In the third period, Molina fought off a charge at the ropes with a hard left.
Sabree Astillero, 14, of Phoenixville PAL won a three-round decision over Noel Gonzalez of Camden Boxing Gym in a 125-pound Junior Olympic encounter.
James Day of Phoenixville PAL dropped a 65-pound three-round Junior Olympic decision to Willis Johnson of William Hicks Anderson. Day went down twice in the first period but recovered to throw numerous punches to stay close in the bout.
In other matches, Ricardo Caraballo of Harrowgate Boxing Club won a three-round decision over Richard Carter of Camden Boxing Club in a 65-pound Junior Olympic test. Rodney Dean of Winslow Boxing Club defeated Chase Alexander of Mascarenhas Boxing Academy in a 106-pound Junior Olympic fight.
Louis Rodriguez of Frazier's Gym downed Louis Cream of Camden Boxing Gym in a 141-pound novice class fray. Max Mentoro of Kennett Boxing Club pummeled Kazamieres Tougines of Left Jab Boxing Club in a 175-pound novice class.
In a 201-pound fight, Kevin Dorin of Frazier's won a second-round technical knockout over Fransisco Sanchez of Camden BC. Alley Santos of Camden BC took s econd-round TKO over Noe Tastaneea of Winslow Boxing Club in a battle of super heavyweights.
In the windup bout of the night, pitting two females, Jacquiline Nichols of Mascarenhas Boxing Academy won a three-round decision over Khadija Hassan of Frazier's in a 170-pound novice class test.
NOTES ... Trophies were presented to the winners and losers. ... Phoenixville PAL executive director thanked Devlin-Rosmos-Kepp and Manny DeMutis for primary financial support in sponsorship of the card.