Timing gear noise after build?

[Daner]

Hello everyone I've been lurking around reading build threads and finding answers to a couple questions and now I have what seems to be a new one.

Truck is a 67 fleetside with a 250 and 4 speed tranny

This spring I brought the engine with me to college and had a machine shop bore the cylinders deck the head turn the crank and do all the valve work and new cam bearings.

I put it all together in my free time and by early June she was running.

My problem now is when I'm driving it. I get what sounds like gear noise in normal driving around 45mph + when the engine works harder. It also happens earlier if I work the gas too hard. My kit came with what it said was matched crank and cam gears. The cam gear is aluminum. When the truck is stopped and I move the throttle on the engine I can't replicate the sound. Seems like it needs to be under load.

Instructions with my comp cam said 30min break in. I got the same gear sound about 20 mins in. continued the break in for 5 min just under the rpm where the noise started and called it good.

I used lucas oil break in additive and also added a jug to the oil when i changed it after break in. I checked the filter and didn't see anything alarming. Engine has about 170 miles on it since break in.

My cam grind isn't radical I think its 255. I'd have to check for sure. I also added a HEI distributer from Langdons.

Also the sound only seems to happen when the engine is warmed up.

All questions and replies are welcome. Thanks