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Old 1 Week Ago   #1
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Tappet noise? What's Normal?

Hi Forum,
As I'm sure my post will show I'm a forum nubie. We have a 1979 S2000. When we got it it was pretty rough. It would probably be easier to list the parts of the car that haven't been worked on. Rather than bore you I'll just say that the worst item was the small end of the number 1 con. rod. It spun the bushing. I pulled the engine and did a full rebuild. (My wife is the driver on this car.) I am very experienced mechanically, but this is my first Fiat. After the rebuild I have the car running very well, but the cam/tappet noise is very loud. I set everything to factory specifications, (which seem REALLY LOOSE to me),and the engine runs great but the tappets are really noisy. Is this typical? I have been building motorcycle race engines and they typically make very little tappet noise. They are also set up at fraction of the clearance called for on the Fiat. My manual says .018-.021 inches cold on the exhaust and .015-.018 inches on the intakes. Does everybody run those standard clearances? Any help would be great.
Bill
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Old 1 Week Ago   #2
Join Date: Jan 2014
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Re: Tappet noise? What's Normal?

Hi Bill,

Welcome to the Fiat Forum!!

I've no figures on the 2 litre engine but I know all the earlier engine used the figures you quote for valve clearance. Official Fiat Workshop manuals say 0.45mm (0.017 inches) Inlet ; 0.50mm (0.019 inches) Exhaust. (If checking valve timing, note the timing figures given by Fiat are with both valves set to 0.50mm/0.019").

I think these engines always sound 'tappety'. Some Fiat Mechanics used to say if you couldn't hear the 'tappets' you needed to check for tight clearances. I've tried setting them 0.002" under the specified clearances but they still weren't silent and I can't vouch for possible damage being caused to valves or seats.

That was bad luck with the small end bushing spinning, only time I've seen this on the Fiat TC's is where the engine previously wiped a big end shell bearing and the small oil-hole in the con rod wasn't checked/cleared out during the rebuild. As you probably know, there are 2 small oil-holes in each con rod, one points towards the auxiliary drive shaft, the other points up towards the underneath of the piston. It's also important to check that there are 2 corresponding oil holes in each upper big end bearing shell being used.... (I hope I'm not causing you to worry by mentioning this now )

Have you got a sound-proofing mat fitted under the hood, this can help quieten things down considerably.

AL.
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Last edited by F123C; 1 Week Ago at 23:47.
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