Reply to "Original PI Big Throat Headers w/ C3L Yates Heads"

Not 'Big Throat' or C3L, but I used GTS headers and SVO A-3 heads on my Pantera, which I think has the same problems. The header flange bolt pattern must be redrilled to match the heads and the headers 'ported' to match the head ports. When bolted on, the collector will run into the springs, so cut a pie-shaped wedge out of the inboard side of the collector, bend the collector flange inboard and reweld the cut closed. The muffler pipe must be bent (or cut & welded) to match the new angle of the collector flange. Due to the cut, one bolt could not be pushed thru the flange, so I welded a stud at that point. The pipe now curls around the spring/shock. Further, one pipe of the left header will hit the gas tank shield; I bolted that header to a junk head, heated 12" of the offending pipe and shoved it inboard a bit with a hydraulic press. Still, I had to shift the tank outward the max amount and dent the gas tank & shield to get even 1/2" clearance. Some parts vendors now sell special headers for use with SVO heads and that would've been simpler. When I did this (1989) you were on your own.... Incidently, the intake also causes problems by pushing the carb backwards 1-1/2" toweard the decklid and up 1" so no stock engine screen will clear an air cleaner; you'll have to build one. I also had problems attaching the stock throttle cable mount to the SVO intake- had to weld a boss in place on an intake runner and bend the steel mount to a new angle.