astrosurfer

Hi again fellas.
Back again with a noise coming from the valvetrain.
It sounds much like a slapping noise.
I think I've narrowed it down to #7 intake....here's how I come to that conclusion...
I've mentioned a boss of mines before who races mustangs blah blah....so I pick his brains a little with my theories or ideas and he gave me a couple diagnosis tricks.
First was a complete re-lash of the valves..done...noise stays.
Next....undo my rockers around where the noise seems to be emulating from and when the noise stops so to speak then I've found the problem.
So I undo a couple of the ones I don't suspect and I get the usual dampening in performance and the changing sound of the motor as it struggles to suck air and fuel to that cylinder.
when I undo #7 intake, after a few turns and the gradual increase in lash noise, the actual slapping sound gets much louder. So I tighten it down again and the noise lessens but does not go away. Even at overlash.
Next thought was a collapsed lifter...so I take it out...inspect it and find no scoring or excessive wear compared to any other, just looks normal.
I stick my finger down the lifter hole and rotate the motor by hand while feeling the cam lobe...this feels nice and smooth with no abnormalities.
I exchange the lifter for the #1 intake to see if the noise moves. This would in fact tell if the lifter was bad I would think. The noise does not move...it's still coming from the back of the motor, and it seems to be in time with the rockers as far as frequency goes.
I'm not thinking this is a lower end noise because I have just installed a remanufactured crank and new bearings...that's another problem I had...got 150 miles out of my first rebuild but I had not done the crank, it was toast.
So down there I have new crank, new stock pistons and rings and new bearings throughout. New timing gears and chain.
I've read another post about the possibility of a worn valve guide.
Could this be my problem?
If so, then how easy are those to change and where would I get them from?
The other thought is worn cam bearings...???

Thanks of course for any and all advice.

Damon

Yeah, it could be a worn valve guide or a broken valve spring on that valve.

I was also thinking an exhaust leak near #7 which could give you almost the same noise. Only difference is that an exhaust leak gets louder the more load you put the motor under. Valvetrain noise is the same volume regardless of engine load.

Doom86

just do your self a favor and check the flywheel if you haven't.

My self and a few others who are much more experienced then me swore it was the valve train tapping, same cylinder even, and it ended up being the flywheel being cracked.

astrosurfer

Well I have actually just recently re-installed the flywheel and stuff when I did the crank.
It was immediately noticeable new noise upon start up.
I saw nothing out of place on the flywheel, but I will look again. However I can only see outside of the converter. I will look though.
Another thing which may get more insight.
First the noise is pretty much a consistent level, so I would eliminate the exhaust leak for now...I've only recently torqued that with new gaskets.
In recollection the noise sort of went away when I was adjusting timing. However to time it right the noise is there. I'm now thinking I need to check I have the timing right on the gears. I am 99.99999% sure that I did it correctly because I matched the 2 dots upon re-install of the crank gear. That I'm going to re-check as I recall a slight bit of slack in the chain, which incidentally did trouble me a bit being new and only 150 miles into the rebuild.
Head bolts and stuff were all torqued on the stand during initial rebuild too.
The noise definitely got much louder and in time with the #7 intake being loosened off a few wrist twists past poor lash if you get me. Therefore I'm convinced it's something to do with that area.
I looked at the spring and it looks good. I have other springs here so I will do the quick spring swap in the name of elimination.
Another thing I notice is that when I throttle and let off...the slap does a few rapids then settles to a steady slap. It really sounds weird and it's ticking me off because that's the only thing stopping me from taking her back out on the road for fear of breaking the motor away from the safety of home. I've been a few short runs around here to see if noise goes away but it continues. Less noticeable higher in the rev band but still there.
Anyways, thanks for the ideas so far. I'll look into them.

Edit: I'm off work the week beginning the 19th. I'm prolly going to pull it and get it on the stand again...see what's what. Not looking forward to pulling that motor for the 3rd time, 4th actually but 2 were on 1 hit...that was another headache by not matching up the tranny right...UFFF