The Ford Barn - View Single Post - The Terry Burtz 5 main bearing engine blocks are back on track.

Pete · 09-17-2021, 03:23 PM

Many modern cast iron cam cores are made off shore and have been for many years. They are plenty adequate for the use they are made for. Herein lies the problem.
These cores are induction hardened. While this process can be very accurate and harden the critical areas only, the heat is usually turned up in order to increase production and as soon as this happens, the core between the lobes is affected and becomes hard in random spots only. The core between the lobes should not be hard.
An easy but time consuming check can be made by Rockwell testing in in 100 spots along a core in between the lobes. Another check can be made by trying to machine in between the lobes with a carbide parting tool for a hot rod grind. This will show the hard spots instantly. This is usually not a problem with overhead valve cams because they are seldom relieved but a core like this can cause early failure in a flathead engine.
If you use a cast iron core that is designed for a specific purpose, there should be no problems assuming you use a lifter material that is compatible. (that can be a whole other ball game)

09-17-2021, 03:23 PM	#411
Pete Senior Member Join Date: May 2010 Location: Wa. Posts: 5,409	Re: The Terry Burtz 5 main bearing engine blocks are back on track. Many modern cast iron cam cores are made off shore and have been for many years. They are plenty adequate for the use they are made for. Herein lies the problem. These cores are induction hardened. While this process can be very accurate and harden the critical areas only, the heat is usually turned up in order to increase production and as soon as this happens, the core between the lobes is affected and becomes hard in random spots only. The core between the lobes should not be hard. An easy but time consuming check can be made by Rockwell testing in in 100 spots along a core in between the lobes. Another check can be made by trying to machine in between the lobes with a carbide parting tool for a hot rod grind. This will show the hard spots instantly. This is usually not a problem with overhead valve cams because they are seldom relieved but a core like this can cause early failure in a flathead engine. If you use a cast iron core that is designed for a specific purpose, there should be no problems assuming you use a lifter material that is compatible. (that can be a whole other ball game)