21-03-2018, 11:39 PM
"It also appears that the photo of the example bushing may have more than one locating hole for the retainer bolt. Is the bushing the only part that keeps the camshaft from moving forward?"
The example bush shows the the locating hole for the bolt that goes through the top of the crankcase; the other hole lines up with the drilling that goes to the oil gallery.
"Is the bushing the only part that keeps the camshaft from moving forward?"
Basically yes. The bush is trapped between the rear face of the camshaft gear and a thrust face on the camshaft directly behind the camshaft's front bearing surface. When fitting up, any excessive camshaft endfloat is reduced by lapping the gear onto the taper, and increased by skimming (or very carefully filing) the front face of the camshaft bush.
The example bush shows the the locating hole for the bolt that goes through the top of the crankcase; the other hole lines up with the drilling that goes to the oil gallery.
"Is the bushing the only part that keeps the camshaft from moving forward?"
Basically yes. The bush is trapped between the rear face of the camshaft gear and a thrust face on the camshaft directly behind the camshaft's front bearing surface. When fitting up, any excessive camshaft endfloat is reduced by lapping the gear onto the taper, and increased by skimming (or very carefully filing) the front face of the camshaft bush.