77 valve noise

[Rupesy]

Just wanted to run this by you guys. When I start the engine, it sounds like a bunch of angry bees and the valve tapping is very loud. It does this hot or cold. The only time the noise goes away and the engine gets quiet is when I get to 2500-3000 and above. Tapping noise goes away, but returns as motor rpms return to the 2500-3000 mark.

I'm checking clearances this weekend, but just wanted a second opinion if I should check anything else. I don't have exhaust leaks or bad gaskets. Definitely coming form the cam tower most noteably the exhaust side, but I think it is both. I'll send in gap info when I have it.

[Rupesy]

Here are the measurements:

Exhaust - counting front front of engine bay back to firewall
#1 - 0.015
#2 - 0.018
#3 - 0.020
#4 - 0.016

I noticed something very odd when I was pushing the car (in 5th). Everytime the lobe got just past pushing the valve all the way down, I heard a little tap/click almost exactly the same as tapping the side of the valve box with a small hammer. It did this for every valve. The cam seemed to jerk slightly as well. Did not seem to hear this coming from the intake side (but I don't have the cover off). I expected rotating the cam to be a smooth operation with no clicks or taps. Maybe I'm wrong and this is normal for rotating the cam with all the oil removed from the box. It's been a LONG time since I did this on a car!

[Rupesy]

OK, now found the bigger issue. The belt was really loose across the top and appeared normal in other places. It does need to be replaced, but it's not terrible. After rotating back and forth, it appears that the cam gear and shaft have play. The gear will move back and forth slightly while the cam shaft stays still! Crud! I was hoping this would be an easy one! I imagine there is probably a broken key or something else??

[narfire]

Try tightening the front bolts....

[FiatMac]

OK, now found the bigger issue. The belt was really loose across the top and appeared normal in other places. It does need to be replaced, but it's not terrible. After rotating back and forth, it appears that the cam gear and shaft have play. The gear will move back and forth slightly while the cam shaft stays still! Crud! I was hoping this would be an easy one! I imagine there is probably a broken key or something else??

The cam gear is positioned on the camshaft with a dowel. If the cam gear is rotating on the shaft the bolt is loose and the dowel is damaged.

Another possibility--Fiat used cam gears in '77-78' that were of composite construction. I have heard of cases where the bond between the phenolic and metal failed. In this case the bolt will be tight, and the relative motion would be within the cam gear.

[fiatfactory]

.

[Rupesy]

These are definitely composite. I have replacements now, but not sure the best way to loosen the nut on the front.

Does it loosen clockwise or counterclockwise?

Any suggestions on how to get those buggers loose?

[djape1977]

to loosen, turn anty clockwise.
most likely way to loosen them will be impact force

[707kevin]

I know this is an old thread, but I thought I'd add some info for others searching for this as well.

Mine sounds slightly diesel-ish as well. A very pronounced clack-clack-clack-clack on the intake cam tower. Sounds like someone is rhythmically tapping a hard plastic screwdriver handle on the cam cover in time with the CAM - not the crank.

The noise is very nigh on the engine, and very easy to determine that it's on the intake side (for mine)

When I had my timing belt partially off to re-time the aux shaft, I was able to see the free play in the cam wheel. WOW!

At low idle sometimes the clacking noise was almost random sounding - it would not make noise every revolution - but it was always in time with the cam speed when it did make noise.

Place a dowel or long socket extension on the cam housing immediately behind the cam wheel and you can totally hear it / feel it.

Anyways, hope that helps someone with a worn plastic composite cam gear noise.