Explain to me again, please

[SBillinson]

Originally Posted by SSDiv6

Darren,

The biggest contributor of failures is dissimilar materials, finishes, treatments, changes on the engine oil additives/composition and break-in process.

The camshaft lobes and lifter surfaces are high load contact areas, and although they may be considered highly polished contact areas, immersed or sprayed with oil, there is still some surface asperity or roughness and the reason why many engine blocks have enclosed camshaft tunnels and many enclose the camshaft tunnel area.

Flat tappet camshafts and flat tappet hydraulic and solid lifters, also need to have a specific taper on the lobe and lifter crown. I have seen too many aftermarket camshafts and lifters that have been ground without enough taper, preventing the lifter to rotate, especially with high pressure valve springs. Many of the ceramic flat tappet lifters that I have seen,do not have any taper on the crown, therefore, you have a very high contact area that eventually will wear, causing a catastrophic failure. When you have the proper taper, the engine will require a camshaft thrust plate or stop to control its movement. Nevertheless, when you have a thrust plate or stop, you also need to have the appropriate clearance because being too tight, will also prevent the rotation of the lifter.

Material compatibility between the camshaft and lifters is also a big source of failures and also the lack of Zinc and other oil additives are also a culprit. My preference of break in oils is Maxima or Joe Gibbs.

For roller cams, I recommend the use of a Calcium Sulfonate based grease or lubricant such as Lubriplate 130-AA Multi-Purpose Calcium Type Grease. Calcium Sulfonate based grease is designed for high contact areas and I apply it to the roller camshaft lobes only.

Excellent explanation.

It bears mentioning that there can also be issues with pushrod angularity. Steep angles between the lifter and pushrod will cause bias pressure on the lifter.

I have offset lifters on my modified engine to try to compensate for the difference in width between the lifters and the rocker arms. They are top-shelf lifters but even with 50 passes on them, you can see the wear pattern from the pressure bias.

The fix is to machine the block so the lifter bores align with the rockers, side to side. That way the pushrods will be straight without using offset lifters. With the splayed head, the bore angles also need to be changed front to back to remove the angularity caused by the valve/rocker placement.

The lifter bores for my application need to look like a standard BBC.