Pontiac Repair: 02 Chevy Express 2500 5.7L V8, ac delco oil filter, chevy express

Question
I was hoping you might be able to help me out with this Chevy van but totally understand if you're limited to Pontiacs only.

Above vehicle has about 80000 miles & I've recently noticed a tapping noise on cold start (ie after sitting overnight or a few days).  

It usually is subtle & only lasts a few seconds if even that.  This weekend was a little more noticeable.  I drove it nonstop for about 40 miles & shut it off with no problem.  It then sat for about a day & a half until today.  Today, it started right up but the tapping was louder and probably lasted around 30 seconds.  By the time I got turned around & out of the parking lot (about 2 minutes), the noise had stopped.

Even with the noise, the engine idles smooth, runs fine & no loss of power or other driveablility issues.  The check engine light has never come on either.  I glanced at the gauges when I heard the noise, no other warning lights on & the gauges appeared normal too.  I also checked oil before leaving for the weekend & it looked fine.

I'm wondering if this indicates a new timing chain is needed, or any other ideas?  If you're able to give me a rough estimate, I'd be grateful.  Thank you in advance for any insight you can give me.

Answer
Hi Austin:

well if it's a ticking nosie and not a knocking noise it's top end meaning valve train noise like a lifter. first off make sure you are using ONLY a AC delco oil filter. it has a check valve in it to stop the oil from draining out of the top of the engine. next thing try draining down a about a quart of oil and add a product called marvel myster oil it comes in a metal qt can. add that to the crank case and drive the van. follow the directions on thacan for exactly how long to keep it in the engine and see it that quiets down a noisey lifter. if not then the engine is going to have to come apart to find the bad part. good luck :)