How much lift can you run without running into cam lobe clearance issues on the late model twin cams?

 

Don't know for sure but the SE260 and SE266 cams have lifts of .609" and .658" respectively and there is no note in the SE Performance catalog that cam chest clearancing is necessary. The SE266 cam shaft is used in the 113" Stage IV Race Kit and SE120R engines. I can tell you that in the early models cams with more than .590" lift required checking to make sure the clearance between cam lobes and the main bearing boss housing as well as the bottom of the lifter blocks was at least .030" and cams with more than .600" lift definitely required clearancing.

EDIT: I ran 590" lift cams in my '02 FLHT with no clearancing; however when I repaced them with .600" lift cams, there was not .030" clear between lobe and the upper corners of the main bearing boss housing and I had to clear.

 

I have heard for sure that 650-660s need machining for sure on late models.

However, I wonder if something like a 625 would be ok?

 

anything over .570 should be checked.ive had cases where .625" had clearance & others where 585`s needed to be machined.rule of thumb,check,dont assume

 

Using .619" lift (Crane 296) cams in my 2000 TC with no clearancing.

 

I've got 9F's spinning around with no grinding BUT doesn't the base circle determine how tall the lobes are? So some cams with the same valve lift might have taller or shorter lobes than others, right? Or am I way off base?

 

It's too easy to check and remove the guess work, so if you want to install .625" lift cams, plan on checking and if the case needs clearing, clear it. Don't forget valve springs either.

 

Right on both counts.