The ZL1 Speed Shop has custom built cylinder heads, and we have examined good retainers and bad. It is important that retainers are shaped in the correct fashion so that adequate rocker arm to retainer clearance is present. Furthermore, the retainer steps that locate the valve spring must be the correct dimension for your valve spring inside diameter. Locks must be made in a way that the fit both the retainer and the valve grooves correctly, and simtaniously. No matter your application, the ZL1 Speed Shop cam help you find trustworthy head hardware that will fit your heads correctly. We offer retainers, seals, and locks for any application whether .800+ lift solid roller application, or low lift flat tappet application. Contact us if you are not finding what you are looking for.