Exhaust headers - which coating?

[xb-60]

Gentlemen, educate me on a couple of points.

- I know a flat tappet cam with solid lifters needs to be broken in, but does a hydraulic cam also need sililar breaking in?

....and....

- Why does a silver ceramic / powder coating turn dull when breaking in a cam, when a satin black coating apparently does not?

I will, however, be having a satin black powder coat on the headers and pipes.

Cheers,
Glen

[tkb289]

Glen,

I will let the more knowable folks here answer your questions about running in a cam, but my understanding is all cams need to be run in for 20 minutes for the lifter (or whatever rides on the cam) faces to bed into the cam lobes.

One suggestion I have is to have the motor run before it goes into the car.

1 - Dyno - If you have access to a shop with a dyno stand, they can do the first start up and check for leaks, run in the cam, make basic adjustments to the carb or fuel injection system and do a few pulls to see how much power the motor is making.

2 - Engine Stand - The same process as above, but on an engine stand. Less expensive and you can do pretty much the same thing, but no horsepower numbers.

3 - In The Car - Run the motor in the car, which it pretty obvious and can be easily done. The only down side is dealing with leaks or more serious mechanical issues, such as a bad lifter, leaky rear main seal or some other problem.

With a property built motor, the chances of a serious issue should be minimal, so as in most decisions when building a car, it usually comes down to three things … time, money and work. The key is how to balance those three.

- Tim

[HighPlainsDrifter]

Hi,
Roller cams do not need a break in period. All other cams need to have special lube put on lobes to be run in at 2000 rpm for 20 minutes to seat the lifters to the cam lobes. The engine oil has to be rich in zinc otherwise the lifters and cam will be destroyed. You can use zinc additives in the ordinary oil and must use them all the time in your engine as modern oils took out these additives for emissions.
Perry