302 Tapping Problem

[timothyt973]

Just looking for some help. I recently had my 302 rebuilt with some mild upgrades, lower cam, new (world) heads, and the list goes on but, basically nothing to crazy just good for the trail and street. Anyhow, I've taken my time braking it in and it has and does run great, however. After giving it a good run not to long ago I now have a tap. Popped the valve cover off and checked each to see if any where loose and they were all tight. Now I'm not an engine builder, but I'm not an idiot, just looking for some ideas to start with. Any help would be greatly appreciated.

Thanks

 

[broncnaz]

While valves may seem tight the engine needs to be rotated to each cylinder (TDC firing) to check each set of valves even then they can still make noise due to the lifter not pumping up.
You might want to go through and readjust all the valves sometimes after break in parts have worn and need readjustment. worst case you have a lifter that doesnt pump up properly and you wont get rid of the tapping unless the lifter is replaced.

 

[77TnBronco]

Check your header gaskets for leaking signs.

 

[timothyt973]

I checked tightness of each valve while it was running and all where tight. I hadn't considered if the header gasket was leaking, doesn't sound like an exhaust leak though, is that what your telling me to check for?

 

[DirtDonk]

Yep. What he said. You'd be amazed at how just the right exhaust leak can sound like a tapping or ticking.
I had a spark plug come loose once (well, I probably left it loose in the first place) and I swore that I had a bad component somewhere. Sounded like a bearing in the transmission. Drove it that way for months until I finally saw that the plug was flopping around.
Tightened it up and, voilá! Ticking gone.
Good luck. Lifters can, and do, go bad, of course, but with any luck it's just an exhaust leak.

Paul