Do Valves need adjusting in '92 3L Camry LE?

Valve clearances do not make a noise under acceleration. Anything directly related to the engine load such as the crankshaft main bearings, conrod bearings and pistons can be the cause, but because you say it is a light-rattling sound, it is more likely to be pinging or ignition-knock.

I;m reasonabley sure that engine uses a knock sensor which is supposed to detect pinging and signal the management computer to retard the ignition timing till it stops.

Pinging sounds like a bag of bottle caps being shaken. Sometimes the cause is too much carbon build-up in the combustion-chamber or low octane fuel. The only other thing maybe, is a cracked piston skirt.

Jason

How about this idea. Buy a valve cover gasket and remove the front valve cover (easy to reach) and check those valves with the engine cold, using an inexpensive thickness gauge (flat steel blades marked with thickness is thousandths of an inch). If the valves in front are OK, chances are, the others are ok. If the valves in front are off, go ahead and pay to adjust them all. To adjust, you need to change the shims. They use a micrometer to measure the thickness of the old shim, and then replace as needed using a special tool to hold down the lifter and gain access to the shim. As a practical matter, if the oil has been kept clean, often the valves don't go out of adjustment. Checking the valves is a simple procedure (once the valve cover is off it only takes a few minutes), replacing the shims a bit more time consuming, and removing the rear valve cover on the six, you're facing limited access as it's close to the firewall. For checking the front valves, Haynes manual is inexpensive and has the procedure.

Acceleration rattle could be advanced timing. Get it checked it will blow your motor Quickly.