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Discussion Starter #1
Hi everyone, this is my first post on the forum. Years back I transplanted the engine from my 74 spider into my Giulietta Sprint along with the 5 speed. The engine had approximately 19K miles on it after a rebuild by a local Alfa shop. It has the Borgo 10.4s, Shankle 7L cams and DCOE 40's plus a MSd 6L ignition. This summer I made a 340 mile round trip per 70 to 80 mph on the freeway. I had excellent oil pressure and the engine ran cool as usual. I recently made a trip to the coast with the car and was cruising at 70 with 3400 rpms when the engine started making a rythmic knocking noise. I pulled over and checked everything under the hood finding nothing interfering with pulleys or such. Since we were only 22 miles from home I started it up and drove on without any noises. My oil pressure was excellent, my coolant temp was normal. We didn't get but a few more miles when all hell broke loose and with knocking noises and by the time I shut it off there was a screeching metal on metal sound. I assumed that the engine had a bearing failure but there was no loss of oil pressure which is supposed to occur during a spun bearing. Coincidentally, I had just changes the oil and filter before the trip. I used the same 20W-50 oil but of a different brand and I was noticing the the oil pressure was slightly higher with the new oil. Another factor that may or may not affect this is while doing a plug check prior to driving home I noticed a very small flat washer stuck in an oily film on the side of the plug well as I was re-installing the plug. I hoped that there wasn't a nut associated with that washer that may have fallen through the plug hole. I doubted this as the car went about 80 miles at speed before the engine problem developed. I have since put small magnets and sticky tape on a welding rod down into that cylinder and have found nothing. The valves all seem to be moving in good fashion also. The cams and cam chain all seem in good shape and I had adjusted the valves not too long before the mishap. I guess my conundrum is why do I have normal oil pressure if a bearing has failed? Unfortunately I will not be able to tear down the engine for a few more months due to space and finances. Thanks in advance for any insights per the above. Dennie
 

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Richard Jemison
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Hmmm

Before and engine changes take the belt off and be sure the water pump and generator/Alternator are operating correctly and are not part of the problem.
Is the front pulley clear of the sway bar?
Is the starter tight on the bell housing?

With the belt off, have someone spin the engine over with the starter. Maybe then you can identify the source or general source of the noise.
 

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As Richard alluded, things like water pumps and alternators can make some pretty wild sounds when they go out. Since you were running cool I think I would be hoping that the alternator bearings fried...

Ok, now for some dumb questions:

  • Did the noise stop when you turned the motor off?
  • Were you still coasting when you shut it down?
  • Do you recall if you lost power when the trouble started?
  • Where there any odd smells when you opened the hood?
Good luck!
 

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Discussion Starter #4
Thanks everyone for these great suggestions. The noise stopped when I shut down the motor. At one point I ruled out wheel bearings with a stopped car and noise from motor running. I was coasting to a stop with the motor shut off and the noise stopped. During this event I noticed no loss of power and I didn't notice any strange smells from under the hood. This afternoon I will check the alternator and water pump for source of noise. Thanks again
 

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Discussion Starter #5
Hi all, I started the engine up moments ago and let it idle at 1000 rpm for about a minute with no noise of any kind coming from the engine. I then increased rpms to 1500 and heard a faint knocking. I shut it off and then removed the belt thus isolating the water pump and alternator from the action. Upon restart at 1500 rpms the knocking was still there only it got a little louder as the engine ran for a few minutes. There is by the way about one half inch clearance between the crank pulley and the crossmember. As the engine was running it still had excellent oil pressure. I am wondering if pulling the head next would be wise to rule out something stuck in a combustion chamber. What say you? Thanks
 

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Richard Jemison
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noise

Check your valve clearances and shims under tthe followers.
Chck the cam timing as well. Is the chain on the lower pulley correctly and not only on the front set of teeth?
 

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Discussion Starter #7
I am back again! The timing chain was correctly running on the pulleys but the chain was a little loose. The cam marks were aligned with the marks on the bearing caps just fine. The valve adjustments should be OK as I adjusted them about 300 miles ago. One thing that I noticed the last time that I started the engine was what sounded like lean spitting from the carbs. This was not going on when at the time this horrible engine noise occured. I am wondering if I have cracked carb to manifold mounts. I will not be able to tear into this engine until later in December. Thanks to all, DC
 

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Discussion Starter #8
I was finally able to disassemble my 2 liter and found that the #1 rod bearing had spun. The bearing as well as the crank journal were coated with deposits of a black material which I believe is carbon. The pistons and cylinder heads were heavily coked and in the sump I found a crumbly black material which I believe is carbon. The new oil was streaked with black. The sump also contained the shiny remains of the rod bearing. I have had an ongoing battle with the carbs on this engine running to rich. I have tried everything possible to lean them out and now I am thinking that the rich running carbs have killed my engine by puttine all of that carbon in the oil. For the rebuild I have purchased new Webers. As for the good oil pressure with a spun bearing I am thinking that my (long gear) oil pump perhaps compensated. Thanks to everyone for your inputs. DC
 

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71 Berlina 74 GTV 17 Giulia Q4
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Does everything possible include jetting changes?
 

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Yes, I went as low as 115 main jets and 210 air correction jets but I think that the carbs were leaking due to old gaskets and seals. I eventually will rebuild these carbs. I had reset the float levels many times and I even tried setting them lower than specs to try to lean things out. DC
 

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Push hard and live
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I had a freshly overhauled set of Webers from a highly respected European specialist kill an engine. One of the carbs had a leaking float, which very gradually filled up, causing a very rich condition on two cylinders. The car ran well, but progressively had a problem idling. A high speed run to check some re-jetting resulted in those two cylinders becoming badly scuffed due to the fuel washing away the oil that normally lubricates the cylinders. Fuel is not a lubricant.

Check your float levels.
 

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It's also possible that the bearings weren't installed correctly in the first place; I've read where that can happen if they aren't placed well on the end caps, etc. That's more remote though, from the sound of things.
 

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71 Berlina 74 GTV 17 Giulia Q4
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I assume the car was originally spica? If so if it has the high pressure fuel pump the fuel pressure regulator could be set so it's feeding with to high a pressure and pushing fuel past the needle and seat raising the float level and causing your problem even if the level is set correctly. It would be on all cylinders and not necessarily easily noticed just by taking the tops off. Just a thought.
 

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Discussion Starter #14
Yes, the car was originally Spica injected but I replaced the high pressure pump will a small low pressure one. I am now in the process of rebuilding the engine and about to send the head to P. Spruell for porting and cams. The exhaust header (centerline) that I was using was for a 1.3 liter engine, I believe, so I am considering building a new header per Jim K's specifications. Thanks all for the good info. DC
 

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FWIW, I suspect that you are running to lean and got knock that took out your rod bearing. A 115 main jet with 210 air corrector is potentially correct for a 1300 or 1600 but not a 2000, especially one that is massaged over, unless you live on Mount Everest. If you were running rich it is unlikely to be your main circuit but either too rich an idle jet or possibly a malfunctioning choke circuit - the latter will wash down the cylinder - been there done that.

Yes, I went as low as 115 main jets and 210 air correction jets but I think that the carbs were leaking due to old gaskets and seals. I eventually will rebuild these carbs. I had reset the float levels many times and I even tried setting them lower than specs to try to lean things out. DC
 

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The cam marks were aligned with the marks on the bearing caps just fine.
This is an observation and probably has nothing to do with the noise. The Intake cam timing mark on a '74 engine is at 114 degrees. The Shankle 7L cam was intended to be timed at 102 degrees.
 
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