Re: Roller rockers install
With stock heads and cam they should go on without any shims. Make sure you are on the cams base circle (the way I do it is to rotate the engine until the exhaust valve opens and closes, just as the exhaust closes, the inlet opens. Once the inlet closes fully you are on the cams base circle), then follow the YT instructions to set the preload correctly. You may need shims but it is unusual with the stock parts.