[X-TECH MAN]

I went thru my books and the heaviest spring listed is on the 1969 six pack 440 and 70-71 426 Hemi Dodge and Plymouth. Its listed at 150 lbs on the seat and 320 lbs on open pressure. Only the 66-67 426 Hemi has a higher seat pressure by about 16 lbs. Use something like that and it would keep the square lobe cams and shubeck style lifters out of pure stock and limit RPM's along with worn out and busted parts . Even the Boss 429 Ford has less pressure on the seat but how many Hemi's (Ford or Chrysler) have you see racing pure stock anyway......LOL. Any combo in the books should be able to live with that kind of pressures. .