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Anyone use the PRC as-cast heads with BTR dual springs?
So I've got a pair of the Texas speed PRC As-Cast heads from Colorado speed and they sent me the BTR dual springs SK001 spring kit. The springs that are normally included with the PRC heads are TSP PAC Valve Springs. Now BTR says to use their spring guide and locator with the springs so that the spring doesn't bind. As you can tell the valve spring guide is much larger and the provided spring seats and locator from BTR don't fit. The provided PRC HW does fit the dual springs well and have the same outside dimensions, but the thickness of the base is different as the BTR one is a good amount thicker. Would it be safe to use the ones that came with the head?
The black locators are for stock guides, the other locators are for bronze guides. The OP was sent the wrong locators. BTR offers locators with their kits for either, you just have to have half a brain and know which ones you need.
As for thickness, it depends on your coilbind clearance and installed height. You want to install the springs at an installed height so that at full lift, you have about .060” clearance from coilbind (Installed Height - Valve Lift - Coilbind Height = Coilbind Clearance).
The locator thickness will change your installed height, with the thinner locator increasing your installed height and coilbind clearance but decreasing spring pressure, and the thicker locators will have the opposite effect.
04-01-2017, 07:25 PM
Anyone use the PRC as-cast heads with BTR dual springs? 
