Isolating engine noises

[StreetRacin89Stang]

How common is a lifter wearing out as opposed to a rocker being loose. I have a similar noise in my valve train and am planing some surgery for this weekend.

Perhaps a cracked valve spring. Im hoping for a loose rocker because of the ease of repair. Would it be worth my time to change to a set of new rockers while im in?? 1.6 or 1.7?

The noise has gotten constantly worse over time and it is just a constant ticking not very loud but it has become noticeable from outside the car. Lemme know what you think.

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89 5.0 GT White w/Blue Racing Stripes
K&N, 73mm Mass Air, Ported and Polished Stock Heads, E303 Cam, MAC equal Length Headers, Off Road H-Pipe, Borla Mufflers, Sway Bars, Strut Tower, Subframe Connectors, Eibach, Koni Adjustables, Pony 5 Stars, 1000 Watt JL Audio System