[alfa] Spider Tapping Noise - Update #1

["Roger Hambro" <rhambro@xxxxxxxxxxx>]

Here's an update on my Spider tapping noise:

Pulled cam cover - Valve clearance confirmed as listed below.
Follower tops smooth and mirror-like
Cam lobes - not worn or pointed

Removed cams and followers - The underside of 2 of the cam followers
had a groove worn into the ID around the inside circumference.  It
appears that the top of the valve springs which are visible sticking
out a bit beyond retainers wore a groove into the follower ID. The 
groove is pretty deep, perhaps half of the wall thickness.  This
may be the source of my noise especially considering the rotation of
the follower, may cause the noise to vary as described earlier.

Worn valve guides?  Time to pull the head...stay tuned.

Roger Hambro
'78 Spider
Algonquin, IL 



-----Original Message-----
From: Roger Hambro [mailto:rhambro@domain.elided] 
Sent: Thursday, November 11, 2004 8:40 PM
To: Alfa Digest Correspondence
Subject: Spider Noise

Can you guys help me identify an engine noise in my Weberized '78 Spider?

Sounds like a valve tapping sound that increases with engine speed, but
occasionally misses a beat.
Tap-tap-tap-(quiet)-tap-tap-(quiet)-(quiet)-tap-tap-tap-tap.....   When
cold, the tapping has more (quiet) beats than taps and as it warms, the
tapping is very regular with fewer (quiet) beats.  Most noticeable while
idling and fairly loud.

I've listened with an auto stethoscope and cannot seem to locate the source.
In general it seems louder at the top of the engine than at the bottom but
this is not definitive.

It is not external physical contact of parts.  Rocking the engine a bit
while running has no effect.  I cannot feel the tapping by placing my hand
on various parts of the engine while running.  Disconnecting individual plug
wires while running has no effect on the tapping sound.  Timing chain is
tight.  Valves are set and verified at a little tighter than spec: 0.018"
Exhaust and 0.016" Intake.  

Ideas?  Diagnostic tips?

Thanks,
Roger Hambro
'78 Spider
Algonquin, IL
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