Cam Shaft Condition

[RodneyCB750K1979]

I just completed measuring the camshaft lobe heights on my 1979 CB750 DOHC. The measurements are within tolerance, but at the lower end of the acceptable ranges.  I'm looking for advice on whether I should replace them. If I do, should I also replace all the lifters and shims?

1979 Honda CB750K Intake and Exhaust cam shafts
9-Dec-12
                                                               
INTAKE CAM
Cam Journal Dia 1.100
OEM Lobe Height Range 1.4567 1.4630
Base Circle Dia. 1.145
Lobe Heights 1.456 1.457 1.458 1.458 1.458 1.456 1.456 1.456
Lobe Lift        0.311 0.312 0.313 0.313 0.313 0.311 0.311 0.311
                                                               
                                                               
EXHAUST CAM
Cam Journal Dia 1.100
OEM Lobe Height Range 1.4763 1.4827
Base Circle Dia. 1.185
Lobe Heights 1.478 1.476 1.476 1.475 1.476 1.476 1.477 1.477
Lobe Lift        0.293 0.291 0.291 0.290 0.291 0.291 0.292 0.292
                                                               

[robs750]

What did you use to measure them and what was the temp. ?

[RodneyCB750K1979]

I used a digital vernier caliper. I measured the overall cam heights from tip of lobe to bottom of base circle.  I subtracted the base circle diameter from the overall cam heights to come up with lobe lifts.  The cam was at 65 F temperature while being measured.

[robs750]

A tenth reading micrometer (.XXXX) would give you a more accurite reading at 68 degrees.Calipers are not really the best tool to use for measuring close stuff like this.
However your readings are not that far off from spec.I would just use the cam.
Even if you bought a used cam(s),they could be worn also.


No need to replace the shims unless you cant get the valve clearance set correctly.
The lifters can also be used unless they are damaged or out of spec.

[Lucky 1]

I would be using a caliper that measures in .001 thousandths in one revolution.


You do not need a new cam.
More importantly what is the surface condition.
For instance, Is the hard facing worn off?

[robs750]

Lucky 1 wrote

 More importantly what is the surface condition.
For instance, Is the hard facing worn off?

Good point!