Valve spring requirements for cams

[Captain]

I looked around and could not find a definitive answer for what is required when running aftermarket cams, so I though I would ask here.

My question is:
What specifically is required of valve springs and retainers when running 272 cams? I know an upgrade is required, and it seems that everyone points towards Ferrera or Crower. I had a head ported out with +2mm valves and upgraded springs a while back but never figured out what springs were used.

I do know that the seat pressure is 70psi and the open is 140psi. According to Crower, their springs have a seat of 60psi and an open of 153psi.

I do not recall if the retainers were upgraded or not, and I am unsure of the exact reason for the upgraded retainers. I am guessing that the OEM retainers are not capable of holding the extra pressure exerted by the new springs, and therefore the upgrade is required. Am I correct?

Any and all help/information is much appreciated.

 

[hvyman]

2mm huh on a 7m head. IDk about that one. Maybe 1mm over sized.

All depends on the lift of the cams. Might be able to get away with some comp cams big block chevy inner springs or might have to go with some bc springs or ferrea dual springs. Also depends on how high your revving.

retainers just use titanium. Basically all the upgraded ones are titanium.

Also depending on how high your revving you might want to look into some shimless buckets. Can get them off echo's and some mr2's from toyota. Will help in not spitting out shims at high rpm and causeing havoc on your head and cams.

 

[toyotanos]

More info needed!


1- Engine
2- Cam brand
3- expected peak RPM

The retainers are lighter than stock ones to help keep the weight down in the valvetrain.

 

[Captain]

Engine is a 7M with .020 over Weisco pistons, Eagle rods, arp head studs, Greddy mhg, port and polish, and the valves are .5mm over 2JZ valves from SI valves. The cams are Toda's and I dont expect to rev past 8k rpm.