I have had my 91 Z28 for about a 6 weeks now, it's a stock 305 TPI/5spd car.

About 3 weeks ago, I put a 3" catback on it, shortly after I started hearing some ticking noises. Presumably I assumed it was an exhaust leak. Took a stethoscope to the welds and found a couple tiny leaks, welded them up and the noise was still there.

After looking into it a little more, I have narrowed it down to the cylinder 6 or 8.

The car fires right up, sounds great in the morning when it's cold. The noise doesn't develop until it warms up, and is typically not very noticeable at idle unless I have been driving quite a bit. It's under acceleration that the noise get's pretty loud and apparent.

Shortly after I bought the car, I found an empty quart of 20w50 in the hatch (side compartment), which immediately made me feel a bit uneasy. It would appear the PO was attempting to quiet the noise.

I am going to pull the valve cover off this weekend, and am hoping for the best case of a loose rocker arm.

My biggest dilemma being, I can get locally a set of vortec heads, slp tpi intake/siamesed runners/plenum etc, the whole package for $300.

If the car ends up needing more than a simple adjustment, this sounds like a good alternative, rather than spending money on the stock heads etc.

One of the vortec's has two exhaust seals that don't seal completely. I would probably have to run them through a machine shop which is added $, and I would hate to do all that and still have the stock cam..Domino affect at it's best.

My ideal situation would be to find a shortblock 350, tear it down, and put it together myself as time permits while just running the 305 in the car, I could then take and get the vortec's all ready to go and everything else ready on my own leisure. But, I live on the 2nd floor of an apartment, so assembling an engine in my living room is probably not a smart idea as I don't have crane to bring it downstairs with.

What would you guys do? I do drive the car daily, so I can't afford to put it under the knife for long, plus I have a one year old son, so I can't afford to just go all in for everything at once. I need a damn garage.

Maybe I'm getting ahead of myself and the rockers will just need to be tightened up, but I kind of doubt it. The car has 170k on it, and as far as I know the engine does as well (New trans and 6k worth of other crap though in the last year).

 

B4 you build a complete car, make sure you rule everything out..
One thing caught me on day was the air diverter valves clicking and clacking.
Exhaust manifolds can crack and make noise also.
Cover all your bases b4 you start throwing coin at it. (thats a heck of a deal on all those parts you listed, you should buy them no matter what)

 

Here's a video, it may or may not be helpful. Any guesses before I pull the valve cover off and check it out? I did check the diverter valve, and that doesn't seem to be the issue, definitely seems to be coming from the valvetrain. The #6 cylinder was the loudest when I put the stethoscope on it.

Not sure why it's showing up three times??

 

Welp, I pulled both valve covers off over the weekend to at least check out the top end of the cylinder heads and was amazed to see how clean it is with 177k on the clock! That being said, I didn't see any red flags, I re-adjusted the valves, a couple rocker arms were a smidge looser than others but nothing alarming at all. Pushrods look good etc.

If I had a garage I would tear into it further, but I'm limited with what I can do being in an apartment.

Any ideas? Lifter(s)? I ran seafoam through it to see if it would free up any lifters if that was the case, but no such luck.

 

Out of all the collective minds on TGO, nobody has any input/suggestions?

 

Well I see your upper penum gaskets are on the wrong side. (my pet peeve lol)
It almost sounds like a rod knock coming and going.
Check smog pump guts for being jacked up, AIR tube lines broken free from mounting/ banging on something and maybe even the cat(s) could be breaking up?

 

Previous owner did the gaskets, I have a new set just haven't had time to re-do them. Rod knock wouldn't be a good thing. Cat is new. I will inspect the smog pump closer.

 

Repost..????

Also take a look at the bracket bolts to the heads and the block, make sure they are tight.
Also a quick peak at the balancer to make sure its not wobbly and hitting the timing cover.
Broken wrist pin?
Belhousing bolts loose?

 

I know the balancer is good, I did the timing not long after I bought the car. (I have only had it about 6 weeks). Everything on the front end is good and tight, pulleys/tensioners etc no wobble, no noises.

Keep the ideas flowing, I'll go down the checklist. My gut still believes it's internal.