Reasons for distributor replacement?

Maintenance/Repairs
21

Many OHC engine distributors had very short shafts and were mounted horizontally and for several reasons were prone to shaft bearing wear.

The old point type distributors would accumulate a lot of wear on the shaft, cam and advance system but the wear was slow in coming like so many other factors and ignored. Down here in the boondocks very few shops had oscilloscopes which would quickly show distributor wear and for many tune-ups were weekend DIY projects and no one had a clue about the details of distributor operation so new points and condenser were all that was ever replaced unless the engine failed to start or had a dead miss due to distributor wear.

22

One thing that causes dist. shaft wear, and especially on the older long shaft distributors, is not changing the oil often enough or allowing an engine to severely overheat.

There’s a small hole underneath the dist.base and the bushing is lubed by splash oil essentially. If the engine has lax oil changes or overheating the hole will plug up due to coked motor oil. After that the bushing starts going south.,

In some cases the advance mechanism may seize or throw a spring or the vacuum advance (if so equipped) will fail.