Just a guess, but what about a loose wrist pin? I would expect that to
be more of a lower end noise, but have never experienced a loose wrist
pin myself.
First, try pulling the plug wire to see if it makes a difference in the
noise. Then try removing the push rods from #1 one at a time to see if
the noise is still there. I've had a similar noise ion the past that
turned out to be a loose or broken bolt holding the fan/water pump
pulley on. Try removing the fan belt for a quick check. What's the odds
that the cam timing gear is loose?
Good hunting.
Peace,
Pat
Thusly spake jover4x4@aol.com:
> List,
>
> I am asking for help in diagnosing a valve clatter for a fellow Wycroc
>member.? His car is a 67.5 1600.? The noise is a fairly loud valve tick at
>idle.? It appears to be most apparent in cylinder #1.? (We used a screwdriver
>as a stethoscope and heard the noise in?the head, chamber #1).? Upon revving
>the engine the noise frequency increases with rpm.? It is definitely an upper
>end valvetrain noise rather than a lower end bearing thunk.
>
> I have adjusted valves several times to different lashes and hear no
>difference.? I have set lash to zero and still no change.? I have replaced the
>rocker assembly with a good used assy I had in the garage and it made no
>difference.? All cylinders are at 160psi compression.? Carbs are dialed in
>correctly and the car idles well at 700rpm.? The noise started after a blown
>head gasket was repaired and a valve job performed.? Owner states all new
>valves were installed, seats cut by hand with a cutter (three angle cut on
>seats), new guides installed and reamed correctly.? Seats were not removed
>when the valve job was performed.? The head was cut .025" and the machine shop
>said it had been cut once before.? So I'd estimate up to .050" has been
>removed from the head.?
>
> About the only thing I can think of is that one or more seats are loose in
>the head, or a guide is loose, or the rocker shaft needs rebushed.? I didn't
>measure the head thickness, but highly doubt a valve is hitting a piston.?
>
> Has anyone encountered a similar problem?? Or can anyone offer some tech
>advise on further diagnosis?? Owner hopes not to have to pull the head again
>but I am afraid that it may be necessary.
>
> Thanks in advance,
>
> John Over
> Denver, CO
> 67 2000
> 68 2000
> 71 240z
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--
Pat Horne, Owner, Horne Systems (512) 797-7501
5026 FM 2001 Lockhart, TX 78644-4443
Pat@HorneSystemsTx.com www.hornesystemstx.com
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