TR4/4A TR4 Camshaft Questions

[KVH]

A few questions:

1) I want to make sure I reinstall my cam correctly. When I'm at TDC can I verify cam lobe positions, like No. 1 cam lobe? What do I look for?

2) About that cam. I have some nicks, very small ones, and only near the edges of the polished lobes. Never in the center. On two of the lobes, the tiny nicks are in fact on the top of the lobe--the high point. Does the entire 1/2 inch width of the cam lobe touch the lifters? Are very small imperfections like that a justification to contemplate a reconditioned cam?

3) I don't really want to fret about the cam bearings, but what do I look for, short of pulling the engine?

Thanks for the help.

 

[TR3driver]

For a stock cam (or the factory performance grinds), both valves on #4 cylinder will have equal lifts when #1 is at TDC firing. But if you have an aftermarket cam, you'll need the information from the cam manufacturer as to how to time the cam.

At the peak of the lobe, the lifter does contact all the way across (although the contact is heavier to one side). You should be able to see the contact pattern, as it will be shinier than the portions that don't touch. If the nicks are deep enough to feel with a scribe (sharp probe), I'd say the camshaft is toast. The stresses are extremely high at the peak of the lobe and any imperfection is going to act like a saw tooth against the bottom of the lifter.

Measuring the cam bearings is tricky, but can be done. But I don't usually bother. If the engine had low oil pressure before, I just replace them. But if the pressure was OK, and the cam journals look OK, the cam bearings were OK. Been a long time since I've done them, don't even know where my home-made tool is anymore.

 

[KVH]

Thanks. I've a list to tackle. Tonight--motor mounts.