engine is noisy!

I'm helping my friend out with a problem. He owns a 1992 Honda civic 4 door I'm not sure which level (dx or what)...he swapped in a new non-vtec D15B JDM engine running with his stock everything else. He had driven it awhile with no problems but some timing belt whiny kind of noises, but he's had this weird problem. When his engine is cold, it will make a weird metal hit kind of sound like it's knocking...but as soon as the engine is warm the sound basically dissapears, it's at all RPMs when cold. He's driven over 10,000 miles with this noise and it hasn't gotten much worse and the engine pulls fine. What the hell is this? Someone told me it could be the wrist pin is loose or something...

If it is worse when cold, and goes away when hot, it's got all the symptoms of valve chatter. Simply adjust the valves, and if done right, the noise should dissappear. If it doesn't then try looking further, but a wrist pin would make noise all the time.

well the valves were adjusted when he got the engine and we checked clearances and they were all within spec...it pretty much goes away when warm although it hits every so often you can hear a hard metal sound, kind of subdued but still there.

The valves are the only real thing I know of that will make that kind of noise when cold and be quiet when hot, unless something else is broken or worn up there.

well dude the only thing i can do there its open your valve cover and put some oil on it and replace everything in place realy quick and start the engine if its tehsame noise its not the valve