delco distributor shaft play
- Thread starter natefank
- Start date
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Any distributor will have significant end play if measured on the "top" where the advance unit is located.
That play is actually retained when the cap is mounted in place and is not an issue.
The "end play" that is an issue is measured between the top of the drive gear and the end of the housing. I set that end play to 0.014">0.017" when I build these distributors. That is where erratic ignition timing comes from as long as the actual mechanical advance system is not worn beyond limits.
That play is actually retained when the cap is mounted in place and is not an issue.
The "end play" that is an issue is measured between the top of the drive gear and the end of the housing. I set that end play to 0.014">0.017" when I build these distributors. That is where erratic ignition timing comes from as long as the actual mechanical advance system is not worn beyond limits.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
A "shim kit" (various thickness shims) is available from msd. That is a starting point. All variations of all brands of distributors used on these engines are considered to have a shaft diameter of 0.500". Actual shaft diameters vary from 0.493" to 0.497". The msd shims are for a nominal 0.500" distributor shaft.
I also use shims I find from other sources (primarily transmission apps) and industrial supply houses. In thickness, they vary from 0.005" through 0.080" in all sorts of thickness spec. Then I use the proper units in a stack if needed to end up with the correct end play once the drive gear is re-installed.
Typically, any IH/Holley distributor shaft will have the drive gear pressed into position using about 3 tons of pressure. The delco distributors normally require only a few light taps (using a puller and brass hammer) to r&r. Prestolite gears can be very hard to remove and re-install, and the spring pin "hole" will only line up in one direction as it's slightly offset.
To determine the shim(s) needed, simply measure the end play with a thickness gauge before removal, then use that measurement to determine what shim (or set) will be needed for reassembly. In some cases, I end up removing a slight amount of metal from the end of the housing itself on a belt grinder.
The end play I want to achieve is not what is referred to in the ihc shop manuals, but is a figure I arrived at through much trial and effort to ensure the best ignition timing forever!
A basic distributor rebuild from ihon runs $45 labor, plus any parts needed. This also includes total rebuild of the mechanical advance unit and a major re-lubrication during assembly.
I also use shims I find from other sources (primarily transmission apps) and industrial supply houses. In thickness, they vary from 0.005" through 0.080" in all sorts of thickness spec. Then I use the proper units in a stack if needed to end up with the correct end play once the drive gear is re-installed.
Typically, any IH/Holley distributor shaft will have the drive gear pressed into position using about 3 tons of pressure. The delco distributors normally require only a few light taps (using a puller and brass hammer) to r&r. Prestolite gears can be very hard to remove and re-install, and the spring pin "hole" will only line up in one direction as it's slightly offset.
To determine the shim(s) needed, simply measure the end play with a thickness gauge before removal, then use that measurement to determine what shim (or set) will be needed for reassembly. In some cases, I end up removing a slight amount of metal from the end of the housing itself on a belt grinder.
The end play I want to achieve is not what is referred to in the ihc shop manuals, but is a figure I arrived at through much trial and effort to ensure the best ignition timing forever!
A basic distributor rebuild from ihon runs $45 labor, plus any parts needed. This also includes total rebuild of the mechanical advance unit and a major re-lubrication during assembly.