Heyward tripled in the final three runs of a five-run fifth inning when his bases-loaded looper down the right field line bounced off the glove of diving second baseman Scooter Gennett and rolled into the right field corner.
Heyward made his first start since coming off the 7-day concussion disabled list Friday.
Tommy La Stella had three hits, Ben Zobrist had two hits and scored three times and Anthony Rizzo drove in three runs to support Quintana, who gave up only Scott Schebler's one-out single in the fifth inning.
Happ homered in each game of the doubleheader, and his homer in the second game was his seventh of the season and the 14,000th in Cubs history. He also doubled and tripled in the first game.
Quintana (5-3) gave up one hit, walked four and struck out seven for the split. The Reds won the first game 5-4 in 11 innings.
Reds right-hander Sal Romano (2-5) gave up six hits and seven runs in five innings, with six walks and six strikeouts. Four of those walks scored.
The Cubs took a 1-0 lead in the third inning when Zobrist walked and La Stella singled to put runners on the corners, and Kris Bryant grounded into a forceout at second, Zobrist scoring.
Happ homered to open the fourth inning for a 2-0 lead. He is the first Cub to homer in both games of a doubleheader since Chris Coghlan on July 8, 2014, also in Cincinnati.
Zobrist and Bryant walked in the fifth inning and Rizzo doubled to drive in the first two runs of the inning. After Happ was intentionally walked with two outs, Addison Russell walked and Heyward hit his bases-clearing triple for a 7-0 lead.
Heyward and Rizzo hit a sacrifice flies in the seventh and eighth innings, respectively, and Albert Almora Jr. doubled in a run in the ninth.
--Field Level Media
Chi. Cubs | Cincinnati | |
Jose Quintana | Player | Sal Romano |
Win | W/L | Loss |
7.0 | IP | 5.0 |
7 | Strikeouts | 6 |
1 | Hits | 6 |
0.00 | ERA | 12.60 |
Chi. Cubs | Cincinnati | |
Tommy La Stella | Player | Alex Blandino |
3 | Hits | 1 |
0 | RBI | 0 |
0 | HR | 0 |
3 | TB | 1 |
.600 | Avg | 1.000 |
Team | Hits | HR | TB | Avg | LOB | K | RBI | BB | SB | Errors |
Chi. Cubs | 11 | 1 | 18 | .306 | 22 | 9 | 10 | 8 | 0 | 0 |
Cincinnati | 3 | 0 | 3 | .107 | 9 | 10 | 0 | 4 | 0 | 0 |