I just bought a rebuilt 355 and put a CompCams XE268 flat tappet cam in it and broke it in. My car makes a ticking noise that goes up with RPMs as I accelerate until about 2500-3000RPMs.

It doesn't sound like rocker tick, but is it possible it could be lifter tick? Does lifter tick usually go away in the upper RPMs? I had followed the instructions in my CompCams cam install manual for setting lash. I went half turn past zero lash after soaking the lifters in oil and smearing cam lube on the pushrod ends and surface that contacts the cam.

Would a loose torque converter bolt do the same thing and go away by 3000RPM? Its a bit late tonight to do any work but I've been thinking about it a bit.

Also, if it is lifter tick, is there any possibility it will ruin the flat tappet cam that I have?

 

Update on the situation. Was driving today and the knock all of a sudden stopped and my exhaust got a bit louder and one of my leaks got a lot worse. Maybe this was all exhaust-related afterall. I did seem to lose performance though as soon as this "knock" stopped, so maybe the exhaust is leaking bad enough all of a sudden to make a drop in performance? Mainly low end. It still pulls decent up top, but it has a lot less low end now.

 

Any exhaust leak can dilute the exhaust gasses that the O² sensor is supposed to sample.

With a significant change in sound and power production, I'd be tempted to pull the rocker covers and check the valve action just to make sure you're not wiping out a cam lobe.

 

Yeah, that's the plan. I'll check it out tonight when I get home from work. I hope that cam's okay.