I have a degree of activity on the FE Forum---people interested in the FE engine such as was used in both passenger cars of the '50s and '60s, and Ford's racing efforts from that time, including both NASCAR and International Road Racing.

The recent changes in oil formulation, and the removal of zinc has led to a high incidence of flat tappet cam failures. Lobes quickly go to nothing and the contact faces of the lifters are worn hollow, often within a few minutes of start-up with new parts. It's commonly said that the ubiquitous use of roller followers has made the old-style tappets obsolete.

Yet the AJ engine design simply substitutes the 'bucket' interface between the cam lobe and the valve tip. The wear-load is taken by the shim in the top of the bucket. And I'm not aware of any significant degree of failure of these parts. A search here has not turned-up any information.

Can anyone shed light on this subject?

 

what has been researched is on pushrod/ rocker arm engines is very high valve spring pressures contribute to lifter wear probs.

roller lifters reduced that quite a bit, maybe not eliminated it completely.

OHC engines,especially bucket on cam, require much softer springs, so stress is much lower, things last longer.

and i believe we can thank the French for that development,Peugeot or Renault, around 1910!

oil has changed ,but old fashioned STP still has Zinc in it! read label.

 

Thanks for your comment. The roller followers in FE engines have virtually eliminated cam failure such as I was referencing.

KS