Mystery ticking on 4th cylinder

[Peters02]

I've a 72 charger with a standard 318 in it.  Rebuilt about 3k miles ago.  I've a ticking coming from the pass side - kinda been there since the rebuild.  When I pull the 4th cyl plug wire it stops.  the sound starts when I put the wire back.  I swapped plugs - same issue, same cylinder.  I swapped wired - same issue, same cylinder.
I pulled the valve cover and everything is getting oiled and feels tight - no discernable difference between the 4th and any other cylinder.
My only and last guess would be a lifter, but would that not be present whether the plug wire was on or not...and wouldn't it run poorly.  At best I may have a slight stumble...maybe and on occasion when idling but nothing that affects driveability.

Any solutions out there?

Thank you very much.
Peter

[Challenger340]

If you are shorting the ticking sound out with the plug wire, it is not valve train related(Lifter, Rocker, Pushrod).

If Oil pressure is fine and constant at operating temps ? then probably not a bearing....
then,
my best guess is Piston Slap(single "tic" that goes away completely with the plug wire off),
and/or
a Piston PIN(if it sounds almost like a double sharp rapping sound) that merely "changes" with the plug wire removed, but still there.

Piston "slap" is a result of excessive Piston to Wall clearance, the sound being the piston rattling around in the cylinder.

A Piston "Pin" problem, again an excessive clearance problem, where the Pin was not "fit" correctly in the piston(usually too tight), or lubed enough upon assembly, so the Pin galls the bore in the Piston on fire-up and "wears" itself loose = noise.

[ChargerST]

Have you checked your exhaust gasket? Could be a leak.

[Peters02]

Thank you for the replies. 
a) I did check the exhaust gasket and had the manifold planed smooth.  I will check again, though.
b) As it is a single tick that goes away w the wire off (not a double rapping) it may in fact be piston slap.  Now the question - is it horrible to have?  Yes, it's annoying, but not sure it's worth tearing the entire engine out to address...unless prevailing wisdom thinks otherwise.

Peter

[Challenger340]

Thank you for the replies. 
a) I did check the exhaust gasket and had the manifold planed smooth.  I will check again, though.
b) As it is a single tick that goes away w the wire off (not a double rapping) it may in fact be piston slap.  Now the question - is it horrible to have?  Yes, it's annoying, but not sure it's worth tearing the entire engine out to address...unless prevailing wisdom thinks otherwise.

Peter

I can't see worrying about it if it is Piston Slap ?
Nothing you can do about it, and many will run forever with no issues that have Piston Slap.
That is NOT to say....
that if it suddenly gets WORSE or louder ? that something else is amiss and it needs immediate attention.

IMO,
The only strange thing about yours to me ?..... is WHY just the one cylinder ?
usually......
if a Machinist goofs on Cylinder to Wall Clearance, he does so on all 8 Cylinders... NOT just "One" Cylinder !

You sure it's not a "knock" which is heavier sounding.... versus a "Tic" which is "lighter/tinnier" sounding ?

[Peters02]

Thanks for the feedback.  No - this is definitely a tick.  It speeds up with the engine but never gets louder. 

[ws23rt]

I had a "tick" on one cylinder in my old hemi RR. -- This was first noticed after a few hundred miles on a fresh engine.

I changed the lifters for that cylinder (hydraulic) and found no change.---Fast forward 75,000 miles from then until I sold the car.  The tick was still the same. No worse and no better.

[Peters02]

Thanks.  I will button it all up and live w it.

I really appreciate the help.

Peter

[Challenger340]

Thanks.  I will button it all up and live w it.

I really appreciate the help.

Peter

A little thicker Oil will shut it up a bit as well.

[Peters02]

I will give that a go, too.
Will know more in a week or so and report back.

Thank you.

[Mopar Nut]

Cracked exhaust manifold?