Rob 97 Z28

iTrader: (3)

I have been trying to pin point the origin of a slight tapping sound. First really noticed it in the begining of the month one day when I ran up to the AZ I work at part time. First thought well probablly need to adjust the RRs slightly. I knew if I left it in O/D and layed into it a bit she still detonated a bit, but manually shifting the 700r it was fine. Got around to adjusting all the valves again, first the CHP way then finally with it running. Still that tap/light knock sound. Today after work I thought, quite possibly the header gaskets are completely shot and the bolts have backed themselves out. Took care of all that, some were looser than others.

Fired it up and still, the Sound remains the same...The engine was roughly 130*, just warming up. Shame of it is is that it doesnt even have 4k on it since i built the whole thing & has excellent oil pressure! 75-80psi on a cold start up and at 190-195* its a consistently strong 40-41 psi and the pressure responds immediately with the throttle...took a video sample to get everyones opinion... I know its difficult to tell where and what my camera phone is at, I was just trying to get the phones mic as close to the knock as possible. Seems like its cyl 1 or 3

Youtube link: http://www.youtube.com/watch?v=jyrO_zzEzeM

As far as the oil goes it always look like normal oil, i change it every 2.5 months regardless of miles (usually WELL under 150 miles each time). I run the PH1218 K&N oil filter equivilant along with a 2"x3.5" filter mag. I run Valvoline Max life 10w-30 with a bottle of lucas Zinc additive EVERY oil change. and it doesnt consume any oil at all its always right at the top of the fill line.

Guest

Why didn't you check for a wiped lobe while adjusting the rockers? Pop the VCs, lay a straightedge across the tops of the locknuts. Are any of them adjusted way farther down the stud than the others? If so, then those are the lobes and lifters to check, after you verify you're not just pulling a rocker stud.

Rob 97 Z28

iTrader: (3)

Having adjusted the valves a few times now I never noticed any one particular rocker lower than its counter rocker for any given cylinder @ TDC...

Guest

I had another thought. The ticking might be a rocker bumping a valve cover?

old z mzn

iTrader: (1)

had that happen. hit the baffle box ever so slightly

z28romance

kind of sounds like lower end to me. hard to tell while hearing it through a camera mike/ computer speakers.

Rob 97 Z28

iTrader: (3)

Thats what my gut feeling is... ive had rockers that were a little loose in the past and its more "tick" like sound, this has some "thud" to it...

z28romance

i had a connecting rod to crank bearing go out on a chev. 4.3 in an astro van and it sounded just like that.

Rob 97 Z28

iTrader: (3)

Thanks for all the input guys! Think I'll be dropping a Blue Print crate engine after this up coming deployment. To many suspension & exterior things to be accomplished already.