It wasn't rocket science for me with the 120ST. SE259 cams/SE lifters and standard SE perfect fit pushrods are within the standard build of the 120ST. No mods to these areas from the norm. Getting SE adjustables was just a choice I made. Now with that in mind, several other cams out there have different diameter centerlobes and require a bit of research to finalize a choice.... luckily I didn't have to go that route.
The adjustable pushrod adjustments vary between manufacturers depending on the thread pitch of the adjusters themselves. S&S have a set procedure for their adjustables at 3.5 full turns out from contacting ( no play ) lifters and rocker at TDC which equates to 21 turns on the flats ( 6-sided adjuster nut ).... SE's are different and call for 2.5 full turns (15 flats ).... just for an example.
The most used material is chromoly for the pushrods and you wanna stick with a high quality. S&S and Feuling are great choices as well. Be warned!!!! Some pushrods REQUIRE the use of aftermarket pushrod covers to gain access to the adjusters as the stock sets are too long. This is in the FINE PRINT of instructions and found on the websites... so if you are going aftermarket, buy the COMPLETE set of pushrods with covers to save you some grief during the install.. not the time you want to find this out. I did my research and found out beforehand.
NOTE ADDED:
The adjustable pushrods are still a 'FIXED' pushrod... you now have the ability to get them JUST RIGHT, rather than slapping in a 'not so perfect' fixed length out of the box. The ability to set and adjust gives you correct length for each lifter and rocker. There is a 0.0200 gap of collapse within the SE lifter springs. The goal is to set the pushrods to 0.0100 into the gap. This allows the hydraulics to still work the additional 0.0100 during operation. ( going from memory right now... so my numbers could be skewed.. it could be 0.2 )
