Car Craft
Click here to find out more!

Camshaft Break-In Guide - How To Break In That Flat-Tappet Cam

By , Photography by

Cam Break-In Basics
In terms of cam break-in we've learned some twists on an old story. In the old days, the drill began with coating the camshaft with that black moly grease. Today you'll notice that most camshaft manufacturers are using a more viscous liquid. The new liquid performs the same job with fewer negative qualities. The next step in the break-in procedure was to preconfigure the engine with proper static timing and fuel in the carburetor, pressure-lube the engine within a couple of hours of startup for best lubrication, and ensure the engine started immediately upon cranking. This is critical because excessive engine cranking wipes the lube off the lobes before the engine starts. Perhaps the most important step in the break-in process is to bring the engine immediately up to a minimum of 2,500 rpm or more. This is vital because most V8 pushrod engine camshafts are not pressure-lubed. Instead, the cam relies on splash oiling brought up from crankshaft movement. A higher engine speed for the first 20 minutes ensures plenty of oil reaches the camshaft. Another tip is to vary the engine speed throughout the initial 20-minute session to ensure that random splash oiling reaches all 16 cam lobes. Of course, it almost goes without saying that the engine temperature and oil pressure are within specs during this crucial break-in time.

All of the above has been covered in detail in stories that date back over three decades and has probably achieved near rite-of-passage status among car crafters. While most enthusiasts are aware of the significant changes in oil, what has received much less attention is the importance of using moderate spring pressures to ensure proper life span. For example, we used a set of typical Z28-style valvesprings in our most recent small-block. They measured 130 pounds on the seat, and that may have contributed to killing the camshaft. During our postmortem investigation, many engine builders said this seat pressure, combined with the open pressures of around 350 pounds, might have been borderline excessive for break-in. These same engine builders now avoid seat pressures above 100 pounds and prefer springs of around 80 pounds on the seat. This reduces the load on the lifter and enhances the potential that the cam will survive. Another engine builder suggested that if the flat-tappet lobes are centered in the lifter bores it can contribute to reducing lifter spin, which will also kill lifters.

Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
0 comments
Car Craft