when you advance the cam the intake valve gets closer & ex gets further,you can retard the cam to get more clearance ,but may lose some lower rpm hp

1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5