Looks like it's time to get real familiar with your motor. Certainly don't drive it. First thing to do is take off the accy belts and see if it goes away. That is the best case scenario.
Next on the list is checking out the front of the engine. This entails removing the timing covers and having a look at the timing tensioner, idler, belt, crank gear and so on.
To do that, you must remove the crank pulley. That's where a lot of uninformed sho-owners stop. It can be a challenge sometimes but prepare yourself with a strap wrench(or 2), a 19MM impact socket and a good 1/2" breaker bar with a pipe over the end of it. You may need help. You may also try the starter bump method, which I'm sure you can look up on google...or even here.
If your crank bolt ends up coming off quite easily, you may have crank cancer, which is well documented here and elsewhere.
If the front of the engine checks out OK, get it all back together and make dang sure your crank bolt is tight. Use brake cleaner and a little brush to make sure the crank snout, bolt washer, and everything else is grease and dirt free. Beg or borrow a torque wrench and get that puppy to spec(you may also want to use loctite on the crank bolt washer, not the threads(just ONE drop in a place that will hold it on...to get the crank bolt off next time, use a little heat to melt the loctite..thats why you put it on the washer...so it will melt easily without over heating the bolt). {I'm sure someone will have a problem with that...oh well.}
Next up would be rod bearings. Are you noticing a flickering oil light at idle or any RPM? Does the RED OIL PRESSURE light come on before you start your car(it's supposed to)?
Before diving under the car to rip off the oilpan, get a tin coffee can and a steel rod(a 1/4 inch extension works) or a stethiscope and place it on various spots on the upper engine(leave the accessory belts off and only run it for 30 seconds or less per 15 minutes). To get the engine to idle at a higher RPM, you can place a dime in front of the throttle stop screw(or a feeler guage). Try to avoid adjusting that screw. You SHOULD be able to get a clear idea where the noise is coming from. If you can't pinpoint the noise, make your judgement call...it's either intake and valve covers or y-pipe and oilpan...the choice is yours, but the stethiscope will really help you choose.
BTW, you should do your rod bearings, either way. I definately heard a little rod rattle at start up...that may or may not be your noise, but if you want it to be a noise for sure, wait...
www.shophoenixproject.com is your friend for the procedures involved.
