Off Trick Flow's Web Page...
Specifications: TFS-51400002 Trick Flow Twisted Wedge Cylinder Heads For Small Block Ford
Material: A356-T61 aluminum
Combustion Chamber Volume: 61cc
Intake Port Volume: 170cc
Intake Port Dimensions: 2.00 in. high x 1.20 in. wide
(designed to use a Fel-Pro #1250 intake gasket)
Exhaust Port Volume: 66cc
Exhaust Port Dimensions: 1.50 in. high x 1.25 in. wide
(designed to use a Fel-Pro #1415 exhaust gasket)
All port locations are OEM
Valves: CNC-profiled, one piece, non-magnetic stainless steel with hardened tips
Intake Valve: 2.02 in. head diameter, 11/32 in. stem diameter, .260 in. tip height. 4.960 in. OAL
Exhaust Valve: 1.60 in. in head diameter, 11/32 in. stem diameter, .260 in. tip height. 4.980 in.OAL
Springs: 1.470 in. diameter single with damper
110 lbs. at 1.800 in. installed height
Open Pressures: 290 lbs. at .500 in. lift and 305 lbs. at .540 in. lift giving 360 lbs. per inch spring rate
Maximum Recommended Lift: .540 in.
Valve Seats:Tungsten alloy compatible with unleaded fuel
Valve Guides:.500 in. O.D. x 2 in. long, special manganese bronze alloy
Valve Seals:Viton
Retainers: Chromemoly steel, machined for 7 degree locks
Locks: 7 degree machined steel
Rocker Studs: 170,000 psi tensile strength
3/8 in. top thread, 7/16 in. base thread
Guideplates: Carburized steel
Requires 5/16 in. hardened pushrods,
approximately +.500 in. longer than stock
You can also find this on their web page under technical specs..
http://www.trickflow.com/product/prfeature_index.htm
It's what I'm running... I'm about .530 according to what I remember...