I want to measure the lobes without removing the rocker arm shafts...can they be accessed enough just by sliding the rocker arms aside?

 

Accessing camshaft lobes without removing rocker arm shafts is typically challenging. Sliding rocker arms aside may provide some visibility, but the limited space and components in the way make accurate measurements difficult. To ensure precise measurements, removing the rocker arm shafts is often necessary for a thorough inspection of the camshaft lobes.

 

Are you measuring for comparison or checking for ware? If you have a high mile engine you also got to take in consideration the rocker pads. Those were out too. (flat spots) so taking the assembly off is almost a must. Can't just measure the side wall of both and expect the ramps to be the same..

If your just having fun, then a dial indicator with a base should be enough to measure the lobe after it passes the pad. Also, keep in mind that you would have to hold the rocker arm against a spring while also taking measurements.. yea good luck with that..

 

Erwin is close with the suggestion to hold the rocker against the sring/valve head, but you don't have to hold the rocker, just adjust the clearance to zero, or maybe zero and a 1/4 turn to preload the rocker. Measure with the indicator tip on the valve retainer. Cam specs give gross lift at the valve at a zero clearance, on occasion with the clearance taken into account.
Measuring on the rocker will get you some odd numbers that won't jive with any specs since the contact on the rocker will, uh, rock and change the geometry with the indicator shaft.