What would make my lifters tap while ideling at a red light ? sometimes the tap is loud and sometimes you hardly hear it.

Lifters are bad..I doubt if it is a rod.. that is why there are lifters to keep it quiet and prevent rod failure.

if you have a stethascope or even a wood dowel i would check the lifters. if you have higher miles this sounds like a hydraulic lifter pumping up. if you change to a heavier oil it will go away or reduce. thats the cheap fix.

You have a mechanical problem the lifter collapse,

If you have a hydraulic lifter that is sticking, sometimes marvel oil or lucas engine additive will help. If the noise is caused by wear at the rocker pivot or the lifter/camshaft, it will not. No chemical can replace a worn part.

It all depends how loud the knock is. A tapping valve can be caused by low oil level, or dirty oil. Topping up or changing oil will solve the problem. A really loud valve tapping is abnormal. Cars sometimes make what you call a spark knock when accelerating hard. Extremely loud knock coming from deep within the engine is a bad sign, which means the engine has failed. Further examination would reveal metallic residue on the dipstick.

could be rod with that amount of miles

adjust valve lifters or it can have tappet wear

If there that noise you better look a little deeper inside engine like oil pump going bad. try some lucas, or stp that might help.

depends, how long between oil changes, how many miles, try and engine flush, sometimes debrise adn sludge will cause a lifter to stick and not move freely causing the tapping noise you hear, if this doesn't fix or quiet the problem it may be to far gone, but if you really love the car get a tear down manual and go to work....put aside a weekend and about 500 dollars it'll be a job

Sometimes the fuel injectors make noise simular to lifters