I just finished getting my motor back together. It was fully assembled at the machine shop. Head was disassembled and refreshed while it was there. Block was rebuilt. I put the motor back in the car and started it up to check for leaks and what not. After a few smaller leaks I fixed them and started the car again. Everything was good. I took it for a drive and after 5 miles the motor randomly got loud. Sounds like lifters or maybe the valves but I don't know. What do you guys think?

 

Did you bleed your lifters prior to installing them?

If not, take the cams back out and bleed the lifters in fresh clean oil.

If you still have the noise you can try upgrading the lifters to revised ones.

 

The machine shop was responsible for doing all of that.

 

I highly doubt they did it! That would be the first thing to check!