Engine upper noise 79 with 74 head

[lm48]

I never had a chance to drive the car after I installed the engine but I did started almost every day. Runs very smooth but time to time has a metallic noise from exhaust cover. Did pull the cover up and find the cylinder #3 gap was out of spec. Re shim correctly but the noise is coming back irregularly. The engine can run for 1/2h with out any noise. When I first set the gaps, the head was on the bench and was checked many times before installation. Is the same valve making the noise #3. Checking with a stethoscope the noise was not there last night. Beside the click of the cams on the exhaust side there was a noticeable rooooo noise but not on the intake. Is this noise normal? Any suggestions bad valve spring, bend valve??

[vandor]

Could you give us a better idea of what kind of noise it is?
Also, what was done to the head prior to installation?

[lm48]

I purchase the cylinder head with no history but look very clean with no visible wear on shims or cam. I send the head with out the cams to a shop to be checked out, replace valve seals, rectified the valve seats and rectified the head surface. No valvs or spring replacement. Because of rectifying the valve seats I needed to replace all the shims. I turn by hand few times the cams, measure the gaps, order new shims, replace the shims, and check one time, all perfect. A day later turn by hand 2 more times the cams, recheck the gaps and all was perfect. Install the head on the engine. All timing was perfect. With new carb install the engine started at second kick. Run for 1-2 seconds just to hear the engine sound. Turn ignition off. I install back the radiator and all hoses next day. Restart the engine and run perfect smooth. After 10 min I got metallic noise like the piston hiting the valves on the exhaust side. Turn of the engine and restart. The loud metalic noise was gone, just left with a typical large gap valve noise. Removed the cam cover, check all gaps and cylinder #3 was half then suppose to be.If the gap will be to big then I will have valve noise but the gap was to small so I should not make any noise. Order new shim, Replace the shim, check and perfect. No problem for daily start until a week later when the ticking came back but not as loud as before. At one point was aflso a small carb backfire. I will be able to record the sound

[lm48]

Very important
I was running Mobil 1 10-40 synthetic with out any other additives. I added zinc additive and run the engine to the normal operating temp and the friction noise went away. I will start the engine cold tomorrow to see if the noise is still there when is cold.

[lm48]

Last night I added to the oil the zinc additive. I started the engine and the friction noise was there, only on the exhaust side. After running the engine for 5-10 minutes the noise started to go in and out until completely disappeared. I will start the engine when I will be back home in the afternoon and check to see if the noise went away for good.

[lm48]

There is no more valve noise but the roooooo noise is still there. Sounds more like a bad bearing. I put the stethoscope on water pump, alternator, engine block, head but I was not able to capture the sound. But again the noise went away last night at the 190 degree. Any suggestion on what I should check

[vandor]

Nothing obvious comes to mind. If the head is warped and they only surfaced the bottom than the camtowers surfaces could be distorted, and the cams could be scraping the housing. It's a long shot, but I thought I'd mention it.
Also a valve could be seizing in the guide and the piston might be hitting it? Another long shot.
Sorry I can't be of more help...

[lm48]

I had a 454 ci engine and one of my driver overheated so bad that spark plug broke inside of the cylinder, then the exhaust valve broke, then the piston and then the head cracked. To a point the metallic noise on my Fiat was the same, so I was assuming sticky valves or bad spring. Only time will tell. As far for the rooo noise is faiding out. I do have a spare engine. Possible an Italian tune up will solve the problem, second gear floor the gas and see what happen, the stronger will survive. Thank you for your input

[lm48]

Mystery solved. Somehow after I install the cylinder head on the block a metallic part dropped thru the spark plug hole into the cylinder no.4. I removed the head few days ago and there are visible marks on the top of the piston and cylinder head. Lucky me the valve do have a perfect seal. Never leave the spark plugs out with out having any sort of plugs covering the holes.

[BEEK]

2.0 motors will make a "roo" noise that comes from the timing belt when tightened too tightly too. its a harmonics noise which comes from the belt istelf