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pegleg
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Last Active: 3 Years Ago
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The flex plates crack and noise follows ! Re your noise problem: get a real oil pressure gage hooked up and see what the actual pressures are. Then you'll know instead of having to guess.
Frank/RebopBristol, In ( by Elkhart) 
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schlockrod
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Group: Forum Members
Last Active: 10 Years Ago
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Could you elaborate alittle regarding the flexplate issue please...........
1957 Thunderbird 312 Fordomatic
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NoShortcuts
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Group: Forum Members
Last Active: 2 Years Ago
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This has NOTHING to do with the noise that you are presently investigating.
HOWEVER, it is a very common problem that is unique to the '55, '56, and '57 'Bird motors. The engine crankshaft damper on the 'Bird is unlike any of those found on the y-block passenger car or truck applications. Behind the pulleys on the damper is a steel 'donut' mounted on a neoprene sleeve.
The neoprene gets hard with age and engine heat and allows the 'donut' to slip, moving toward the timing chain cover. When viewed from above, or even from the side, it appears that there is no interference. That is, the 'donut' seemingly has not moved back enough to contact anything that it shouldn't. However, if you can observe the 'donut' at its lower side rear edge, you may see that the lower edge is potentially just touching the front steel engine support that is attached to the timing chain cover. SOMETIMES, you'll get a random tweet from the 'donut' brushing the curve of the front engine support at idle.
The 'donut' can be re-vulcanized in proper location and the damper re-balanced if you encounter this problem. It's an alternative to buying a new unit and costs less to have done.
I'm sure that you're thrilled with all the information we're sharing with you. 
a.k.a. Charlie Brown
near Syracuse, New York
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NoShortcuts
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Group: Forum Members
Last Active: 2 Years Ago
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IF the noise stays the same as you disable one spark plug at a time, I would suspect the main bearings. IF the noise stops when a particular cylinder is disabled, I would suspect a connecting rod bearing.
Y-blocks have a strong bottom end. I would be more expectant of a rod bearing problem than a main bearing problem.
The above said, I'm a hobbyist. There are Forum members who have seen the inside of far more y-blocks than I have and who have raced y-blocks that I never have. Hopefully, the Ted Eatons, John Mummerts, Tim McMasters, Hoosier Hurricanes, Glen Hendersons, Frank (ReBop) Rices, Gary Burnettes, Harry Huttons and OTHERS on this Forum will weigh in on this. There are a large number of VERY knowledgeable, very experienced engine builders on this site.
(Listing names is a mistake, Charlie Brown! With your OLD mind, you're BOUND to leave off SEVERAL somebody's names that you KNOW you should have listed!)
Hope this helps. 
a.k.a. Charlie Brown
near Syracuse, New York
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schlockrod
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Group: Forum Members
Last Active: 10 Years Ago
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Just to be clear, you think its possibly rod bearings, not main bearing? I can certainly check both with the pan off.
1957 Thunderbird 312 Fordomatic
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NoShortcuts
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schlockrod (5/17/2014)
Yes I have a Fordomatic. As I said in the beginning, it only made this "sound" when the car was fully warmed up and sitting idle. Now, before all your suggestions came in, I changed the oil filter and added a quart of Rislone oil treatment, the thick stuff. It is now NOT doing it or at least I ran it to hot temperature and I did not notice the noise. That doesn't mean I fixed it as such, I need to drive it more and see. Based on this so far, wouldn't this eliminate the flex plate problem mentioned by a few?
I'm with Paul. IF what you've done has 'eliminated' the noise, the transmission flexplate is most likely out of consideration as the source.
I'm also with DryLakes Racer and Charlie. The Rislone oil treatment is basically an oil additive that increases the oil's viscosity. There are other products like STP that also will do the same thing. Probably, the Rislone oil treatment has MASKED the engine problem. I would recommend again changing the oil filter and put the correct weight oil in the engine. (Lord knows what the person selling you the car had in the oil pan in desiring to sell the car! ) IF you've still got the noise once the engine has warmed up with the correct oil in the base, consider doing what I suggested previously.
- attach an oil pressure gauge to determine the oil pressure at idle when the engine is at normal operating temperature. IF it is low at idle, it could be clearances within the oil pump (wear) or a stuck by-pass valve in the oil pump OR bearing clearances in the bottom end of the engine being excessive. - disconnect one spark plug at a time and see if the noise goes away. If the noise goes away when a particular cylinder is rendered 'dead', that is likely a cylinder that has a problem with a connecting rod bearing.
Personally, I would NOT drive the car to see if the noise gets better. IF you throw a connecting rod, it's BIG trouble. 312 blocks are out there, but you don't want to have to buy one...
Hope this helps.
a.k.a. Charlie Brown
near Syracuse, New York
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charliemccraney
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Group: Moderators
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If it is something like a rod knock and that "fixed" it, it is time for a rebuild, before it gets worse.
Lawrenceville, GA
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DryLakesRacer
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Sent a PM. I would stop driving it now. Get the pan off and check all of the rod bearings. A few hours and a pan gasket set is worth the peace of mind.....
56 Vic, B'Ville 200 MPH Club Member, So Cal.
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paul2748
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If the noise is gone by what you did, I would say it eliminates the flex plate issue.
54 Victoria 312; 48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ
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schlockrod
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Group: Forum Members
Last Active: 10 Years Ago
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Guys, all good information. Here's where I stand on this issue. Yes I have a Fordomatic. As I said in the beginning, it only made this "sound" when the car was fully warmed up and sitting idle. Now, before all your suggestions came in, I changed the oil filter and added a quart of Rislone oil treatment, the thick stuff. I took the drain tubes on both sides off the valve stands and shimmed or blocked off half of the passage ways in the tubes to reduce flow (increased pressure) and reinstalled. It is now NOT doing it or at least I ran it to hot temperature and I did not notice the noise. That doesn't mean I fixed it as such, I need to drive it more and see. Based on this so far, wouldn't this eliminate the flex plate problem mentioned by a few? Still open to comments, thanks guys.
1957 Thunderbird 312 Fordomatic
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