Clacking in valves

[rasouth]

This is kinda a follow up to "#3 intake valve making noise" that I posted a while back. Upon further examination of the cams, shims and tappets a friend of mine and I think that the lobe of the cam is hitting on the edge of the tappet, (or cup) that the shim sits in. When the cam is at 90 degrees from pointing up (the position that you would measure the gap) it looks as if the cam is rubbing on the shim and I cannot get a feeler gauge in between.
Can the cam shaft be too close to the shims and tappets? Can I put two gaskets under cam housing to increase the distance? Can I shave down the tappets without causing trouble with the shims?
I found a FIAT mechanic here in Riverside but I haven't had a chance to get the car to him. I don't want to drive very far if I might screw the engine up in the prosess.

[Fiat1980spyder]

Do a valve adjustment you need to get a shim kit and you need special tools to hold the the valve down while you slip out the shim and measure it to find the right shim needed to add or subtract from existing. grab 2 valve covers gaskets while your at it and if you have fuel injection get the gasket for the top of the intake manifold.
2L twin cam
Clearance: Intake 0.015 to 0.019in
0.41 to 0.48mm
Exhaust 0.018 to 0.021in
0.46 to 0.53mm

[narfire]

Kinda scratching my head on this one. I found that the cam won't hit the edge of the tappet untill you get down to a 3MM shim or less. I had a 2.9 mm and it was making contact so I had to change valve. (Another story why).
Did the cam/ valve train make a clacking sound from day one you bought it? or just happen one day? I'm not sure about this but perhaps a keeper on the valve let go,allowing the valve/springs to ride up and into the bucket of the tappet, always putting pressure on the tappet,then pushing the tappet into the cam lobe... no clearance.
Might have to pull the cam tower if that is the cause.
Hope some other could confirm or poo-poo this therory.
Chris

[fiatfactory]

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[rasouth]

The problem came on suddenly. I was repainting the car and every couple of days I would start up the car and let it run for a while. One day after the engine warmed up I noticed a clacking noise coming from the top of the motor. After painting I removed head, cleaned it, removed valves and springs, checked for bent valve, (none found), had one valve guide that looked iffy so I replaced, put motor back together with new gaskets and adjusted valves, did an oil change, installed an oil gauge, checked timing, adjusted points and rebuilt carb.
The cam lobes have a little scoring but none look real bad or flattened. None of the shims are less than 3.60. The two in question are 3.60 and 4.10. I was wondering if when I put the cam housing back on if I compressed the gasket too much and this is causing the cam to be too close to the tappets even if the gap is correct.
Other than the noise the motor runs pretty smooth, good acceleration and good idle speed. It's just the noise that is a problem. The noise only starts after the engine has warmed up for a few minutes. The oil pressure is around 26 to 28 PSI when the noise starts and I get plenty of oil pumped to the cams.

[narfire]

I read it that #1,2 and 4 intake are at spec... around 17 thou. clearance and when you now measure #3 intake it is zero or you cannot get a feeler guage in there. When you put the head/valves back together you had them all at spec before starting the engine and ran great till recently. I'd try a thinner shim first to see if you can get some clearance and if the shim is still pushing up against the cam lobe, I'd think something under the tappet has let go and you have the spring and retaining washer pushing up inside the tappet and against the cam lobe.I'd think,correct me if I'm wrong but if a keeper let go would'nt the valve slide back down? Just thinking here,again hope someone else could chime in
Any chance something fell/got sucked into #3 and a valve is now nicked or something?

In my case,I had a misfire and found it was #1 plug was pooched. Took the lead off and the plug was cracked and broken. I got a vacume and thought I got all the porcelain. When I pulled the plug a small chunk must have fell inside and crunched around a second before being expelled. At the beginning of the season(here anyway) I posted about a louder tapping noise and perhaps a bit of a "flutter". I recently took the head off to replace with a tweeked 2L head. #1 had some divits in the combustion area and I think perhaps nicked a valve seat or something.
Just wondering,I'm sure there are several reasons for a louder tapping noise, but I'd figure out why you don't have clearance anymore.
Chris

[rasouth]

ALL valve clearances are within specs. What I was trying to say was that when the cam lobe is pointed sideways, not up where you would measure the clearance and not down where it is pushing the valve open, just where the lobe is half way between. It is at this halfway point that the rounded part of the camshaft, not the lobe part, is touching and I cannot get a feeler gauge between the cam and the shim.

[majicwrench]

Methinks you are chasing ghosts. The cam has long ramps to open the valve smoothly, I would not worry about not being able to get a feeler gauge in tween the cam and shim with lobe 90 deg from valve.

[rasouth]

Methinks you're right. I think I am going a little overboard about not being able to fit a feeler gauge under the lobe at 90 degrees. I just don't see a reason that the #3 valve is clattering. Engine runs fine, good steady idle, oil pressure is okay, valve clearance within specs, timing is good,...It's just the one valve making the noise.