Clark was one of 17 players to break par on Friday at Bayonet Golf Course and he broke into red figures early with a seven-foot birdie putt at the third. At the fifth, Clark played a 6-iron 20 feet from the stick to set up another birdie but a bogey at the ninth dropped him to a front-nine, 1-under 35.
The 25-year-old from South Africa rebounded immediately after the miscue at nine. Clark roped a 3-iron to 12 feet at the par-5 10th which set up eagle but he squandered opportunities to go lower.
At the 11th, Clark missed a three-foot birdie try and at No. 15 he failed to convert a two-footer for birdie. His drive at No. 16 found the rough and he was unable to get up and down for par.
'I missed two putts that hurt a little,' said Clark, who won twice last year. 'I hit the ball well and haven't missed any fairways. I've missed five putts inside of five feet over two days.'
Clark is playing in only his second Buy.Com Tour event of the season. He is a member of the PGA Tour but has a medical exemption after tearing cartilage in his right wrist in February.
'It's still a little weak,' said Clark, who won twice last year on the Buy.com Tour and qualified for the PGA Tour by finishing third on the money list. 'I've practiced a lot the last month but haven't been hitting that many balls.'
Carter fired the lowest round of the day with a 5-under 67 and that was because he had the shot of the day. At the par-5 10th, Carter roped a driver down the fairway and then holed out a 6-iron from 185 yards out for a rare double-eagle.
Heinen and Campbell each posted rounds of even-par 72 on Friday. Heinen has four top-10 finishes on tour this season while Campbell picked up two wins earlier in the year.
One more victory and Campbell will get to ascend to the PGA Tour under the Buy.Com Tour's 'battlefield promotion' stipulation, which allows a player who wins three times in a single season to immediately move up to the big leagues.
Charley Hoffman, Tjaart van der Walt, Deane Pappas and John Rollins share fifth place at 2-under-par 142.
Jamie Rogers and Todd Fischer are knotted in ninth at minus-one.
First-round leader Vic Wilk struggled to a 5-over 77 on Friday and fell into a tie for 15th at plus-one.
The 36-hole cut fell at 4-over 148 with 63 players qualifying for the weekend.
Click Here for Full-Field Scores from the Buy.Com Monterey Peninsula Classic.