[Mercmarc]

Hello All,

MercMarc here with a question.

Facts as I know them:

1953 239, dual carb, Isky 88 cam, Adjustable lifters, Aluminum cam gear, EAB heads, stock bypass oil filter style.

1950 239, dual carb, Isky 88 cam, Adjustable lifter, Fiber cam gear, EAB heads, full pressure oil filter upgrade.

Both engines experienced failure with in 10 hours of run time due to the cam shaft walking forward into the cast iron timing gear cover, eating the aluminum cam gear sending metal particle throughout the engine. The second engine has a fiber gear and was caught earlier so little cam gear damage but the cast iron cam gear cover was ground away by the 4 cam bolts. Both engines were professionally built by an west coast shop. Turn key engines, both engines started and ran great, a noise was heard radiating from the distributor area sounding very similar to a dist rotor hitting the inside of the dist cap. After removing the dist cap there was no evidence of the parts hitting each other.

Note:
The first engine was replaced in totality without question or disassembly by the shop when I told them I was having trouble with the engine.

Question:

What would cause a camshaft to walk forward on these engines?

Thank you