* More mid-range and hi end power. Idle un-affected. Head setup required 1980 & 1981 engines: The height of original stock H/D valve guides restricts spring travel (and cam lift) to .430 or less!
* If you are installing cams in a shovel engine, the Andrews valve spring collars and related parts will make things go a lot smoother. The Andrews springs and collars are designed for easy installation and maximum reliability.
– Upper Spring Collars AP-271100 (high lift) or AP-276150 (Mediu