Hotrodder

I'm planning to change to 1.6 roller rockers on my modified Vortec heads.
Valve lift is 0,500". Springs will handle up to 0,550".
Springs, Retainers and seals are bought as a ,550 lift kit from Alex's Parts.
Retainers are extra thin to make for higher lift.
The cams RPM range is 1300-5500.
I have measured the valve to seal clearance to .571"
-Max lift with 1.6 rockers will be .533"
Is the 0,038" safety margin enough?

It's a hydraulic roller cam.
Some say that the hydraylic lifters are somehow more forgiving if the retainer should hit the seal?

NoEmissions84TA

iTrader: (1)

Minimum recommended clearance should be no less than .060".
When the seals are new and soft, they can take a couple of hits.
But over time the seals harden, and should it hit in that case, the base of the lifter collapses and becomes a lathe to the camshaft lobe (flat tappet - hydraulic or solid).
All that shrapnel then circulates through your entire engine - destroying everything. Ask me how I know?
If the lift of your camshaft is greater on the exhaust, then you might want to consider just running the 1.6 rockers on the intake side only. Usually the intakes is the only side that 1.6 rockers show any benefit.
I use Alex's parts also. I only have good things to say about his parts.

Hotrodder

Thank's for Your answer. That's what I suspected.
I guess I'll stick with the 1.5 rockers then.
I know cylinder head casts differ, but according to Alex's Parts, these parts would make Vortec heads able to accept up to 0,550 lift without any machining.
With 0,060 safety margin, they won't even accept 0,511".
I'm pretty sure I knocked the valveseals all the way down, as well.

cardo0

Yes most of your cam manufacturers (like crane) say no less than 0.060" clearance to coil bind with the valve springs but I don't recall any requirement for spring retainer to valve seal or valve guide. But ya know a lot of stock GM combinations don't seem to have that much clearance to coil bind. I believe the LT4 Hot Cam valve springs didn't have that 0.060" clearance on LT1 heads but I could be wrong as I lost all that information and can't look it up. I'm under the impression the long slow/gradual ramps of GM lobes may allow less clearance but I admit it's just my guess.
Now for valve spring retainer to valve guide/valve seal clearance you definitely need some but I can't provide a number for you - my apologies.
Hope this makes sense to you.