Model A & B & G28T

Ford Garage

Camshaft Thrust Plungers

Shown below are some aspects of the A-6275 camshaft thrust plunger and A-6276 spring to be aware of.

These parts are located in the front timing cover and are used to control the camshaft fore/aft and keep a rearward load on the front nose of the camshaft.

It is important that the correct spring with the proper size, stiffness and preload be used in conjunction with a plunger of the correct dimensions, heat treat, and finish.

The spring and plunger shown above were seized in the bore of a front timing cover casting. They were removed by welding a rod onto the plunger to apply force to break it free, while also applying some heat. It was seized in place due to corrosion and dried oil sludge.

Once apart, it was found that the original spring had previously been replaced with some non-original softer small wire size spring. That replacement spring did not have the strength to control the camshaft, and the cam kept the plunger compressed in the timing cover where it then seized.

After trying and checking several reproduction plungers and springs I found that they were all different dimensions and quality compared to the originals. (Gee, what a surprise!).

Pictured above is a comparison of the original plunger and spring from a G28T engine on the left, and good Model A reproductions on the right. Note the different plunger face design of the G28T. Model A and B plungers used the cross groove design like the reproduction on the right.

This particular (quality) reproduction plunger was purchased from Ron Cloat, and was carefully finished and heat treated steel, as per the original design. Most other reproductions I have seen are zinc-plated mild steel, and have very rough machining and surface finish. No thanks!

The reproduction spring on the right was also purchased from Ron Cloat, and appeared to have identical dimensions to the good original.


More Camshaft web pages on Ford Garage:

  1. Model A & B Camshaft Gear Front Timing Cover Differences
  2. Model A & B Original Ford Camshaft Details
  3. Model A & B Original and Reproduction Valve Tappet (Push Rod) Details
  4. Model A & B Camshaft Timing Gear Varieties
  5. Model A & B Camshaft to Crankshaft Positioning

January 2004