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6,298 Posts
Eibach springs are fine on the stock valves. Not enough controlled test data to make a judgement as to whether the heavier springs are good, bad, or indifferent to the stock valves breaking. Most of the stock valves break at the keeper groove. Most likely due to float. So, the eibachs should help prevent this. Again, the data is somewhat circumstantial...
Known fact is the Supertech valves and springs are junk for the 2ZZ. No flame suit needed for that statement, as the evidence is there.
Ferrea springs are not needed on motors with sub ~8500 operating ranges... Ferrea valves are the only replacement valves to install...
Ti Retainers are not needed, but they sound cool.
Bottomline, should be fine to upgrade the springs on the stock valves. The Eibachs will support the Stage 3 cams. No idea if the stock valves will mind the extra lift/duration, but don't see why they would.
-Phil
Known fact is the Supertech valves and springs are junk for the 2ZZ. No flame suit needed for that statement, as the evidence is there.
Ferrea springs are not needed on motors with sub ~8500 operating ranges... Ferrea valves are the only replacement valves to install...
Ti Retainers are not needed, but they sound cool.
Bottomline, should be fine to upgrade the springs on the stock valves. The Eibachs will support the Stage 3 cams. No idea if the stock valves will mind the extra lift/duration, but don't see why they would.
-Phil