Earlier in the day, Justin Sommerman hit a grand slam as Washington Township beat Vineland, 14-2, at Deptford.
Two victories, 28 runs, two games cut short to five innings by the mercy rule.
Counting a 7-5 win over Audubon in the quarterfinals on Saturday, as well as a 12-7 win over Cherokee in an Olympic American game on Friday, the Minutemen scored 47 runs in four games in a little more than 48 hours.
"These guys would play every day if they could," Washington Township coach Bill Alvaro Jr. said of his squad, which has won 12 in a row, improved its record to 21-5 and risen to the No. 1 spot in The Inquirer top 10.
Camden Catholic (17-9) stunned Bishop Eustace by a 4-3 score in the semifinals on Sunday afternoon at Eastern.
Christian Bilan ripped a two-run double to back effective pitching by sophomore Dan Hartson as the Irish advanced to the tournament title game for the first time since they won the inaugural event in 1974.
But in the championship game, Camden Catholic walked seven Washington Township batters and all seven came around to score. Two other batters were hit by pitches.
"That's the ball game right there," Camden Catholic coach Bob Bergholtz said.
Washington Township scored three in the first, four in the second and seven in the third against Vineland, and one in the first, seven in the second and three in the third against Camden Catholic.
"We're all taking good approaches at the plate," Long said. "We're just trying to put everything hard in play."
The Minutemen were determined to win their first Diamond Classic title since 1993 and second overall. They used ace pitcher Mark Scarpa, a junior righthander, rather than hold him for Monday's first-round South Jersey Group 4 tournament game against Toms River South.
Scarpa pitched a three-hitter with four strikeouts and zero walks. He faced just 17 batters.
"Once our young [pitchers] got us through yesterday and earlier today, we absolutely were going for it," Alvaro Jr. said.
Washington Twp. 173 03 - 14 11 0
Camden Catholic 100 00 - 1 3 0
WP: Mark Scarpa. LP: Tom Gallagher
3B: WT-Ryan Long 2, Tom Hildebrand.
HR: CC-Joe Craig.
Bishop Eustace 001 020 0 - 3 6 0
Camden Cath. 300 100 x - 4 6 2
WP: Dan Hartson. LP: Justin Hagenman.
2B: CC-Dom Messina, Christian Bilan.
HR: CC-Mike Wheeler
Washington Twp. 347 00 - 14 6 0
Vineland 002 00 - 2 5 3
WP: Chris Haruch. LP: Mark Rowan.
HR: WT-Justin Sommerman.
Contact Phil Anastasia at email@example.com. Follow @PhilAnastasia on Twitter. Read his blog, "Jersey Side Sports," at www.inquirer.com/jerseysidesports