If you have a tick at cold start that slowly goes away as the engine warms its probable that your exhaust manifold is warped and it broke a bolt(s), or you just have a broken bolt.
I had my right manifold replaced under warranty at 30K miles.
If you tick arises at other times, here is one discussion of three causes (out of several) for
Hemi tick (other folks swear it has to do with lifter lash/gap issues) but a lot of folks have seen better lubrication with engine oils higher in Molybdenum reduce their tick:
According to this source (an engine treatment/lubricant vendor) There are 3 culprits that cause the "Hemi Tick" heard at idle and just off idle.
1) First, fuel used have higher amounts of sulfur and lead (tetra ethyl or tetra methyl) to lubricate and cushion intake and exhaust valves in the old days. When EPA decided to go to unleaded fuels, flash chromed and hardened valves and seats were produced trying to deal with the lack of lubricant. This did allow engines to live longer than if they had soft valves and seats. However, when EPA went to increasing percentages of ethyl alcohol, that all changed. Alcohol absorbs moisture and strips lubricity (thins oils lubricating properties). That was bad enough, but when EPA also reduced sulfur content from 130 parts per million (ppm) to 30 ppm, it really produced a perfect storm. Both the intake and exhaust valves are now hitting against the valve seats with no cushioning from the fuel at all. This causes wear, and of course....noise or TICK.
2) The second part of the Hemi Tick is that fuel injectors depend on at least 70 ppm. When EPA went to the ethyl alcohol and less than 30 ppm sulfur, injectors lost cushioning from fuel allowing them to click or tick while also building up gum and varnish.
3) The third part of the Hemi Tick arises because the Hemi, like most engines today has a very short piston skirt and thin rings with virtually no land area. With the comparatively higher compression and spherical crown it causes the piston try and rock in the bore. This is why Chrysler adds a moly piston skirt coating--to cushion the short skirt. The problem is that as miles rack up, the moly is worn off and a louder engine or tapping noise begins to occur. This actually contributes to more aluminum in your oil analysis.
My $0.02: Smog control and pollution abatement are worthwhile efforts--I remember when the whole world seemed to smell like unburned gasoline from the tailpipes of cars in the 60's and 70's and applaud the vast improvement in air quality achieved since that time.
But the EPA tends to take a suck it up cupcake approach with the auto industry and the engineering and technology often lag the sometimes more symbolic than substantive authoritarian mandates by the Feds. Additives and changes in your brand of motor oil, as well as periodic oil analysis, can assist in extending the life of your engine.
Since opinions vary you might want to monitor the responses this post receives to get THE REST OF THE STORY..... I'll certainly be watching
