57 Bird 312 Harmonic Balancer question ????


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By Lex - 12 Years Ago
Hi All, I'm new here to the forum. I took a 57 T-Bird in on trade for my Cobra Roadster a few weeks ago. It's a D Bird with a 312, PB and PS. Can the balancer slip on these motors? The previous owner said he tried to set the timing and when he did it with the factory marks the car was really sluggish so he just moved it up enough to where he thought the car ran good. I put a load on it and it's not detonating. I think I feel a little harmonic vibration in the steering wheel at about 2500 rpm while cruising. Also can the timing pointer get moved? Last, what's the best way to find exact top dead center on these motors with it in the car. I have a dial indicator and magnetic base etc. Thanks for any help before I unload $500 on a balancer that may not be needed. Lex
By Ted - 12 Years Ago

Hi Lex. Welcome to the forum

First question is whether you have a Thunderbird damper or a car/pickup damper. The Thunderbird damper is considerably longer which makes them easily identified. The damper rings on the passenger car/truck units where the timing marks are located are prone to slipping thus making those a problem when trying to time the engine. The timing marks on the Thunderbird damper are on the pulley itself and any damper ring slippage on that damper will not affect the timing marks.

For double checking the existing TDC mark, two methods come to mind. The first is to simply remove the valve covers and rotate the engine until #1 or #6 cylinders have equal intake/exhaust valve opening at overlap. The exhaust is closing while the intake is opening. When both valves are open equally, the TDC mark is expected to be within 4° or so of TDC. Use a straight edge across the retainers to insure equal opening amounts.

The second method is to remove all the spark plugs and then put a piston stop in either the #1 or #6 cylinder with either piston down in the hole a good distance. With the battery disconnected, rotate the engine forward by hand or with a wrench on the damper bolt until the piston contacts the stop. Mark the damper where the timing tab is pointing. Then rotate the engine backwards until the piston again contacts the stop. Again mark the damper where the timing tab points. Exactly halfway between your two new marks is TDC. If all is well, the timing tab should be pointing at the original TDC mark on the damper.
By NoShortcuts - 12 Years Ago
Hi Lex,

Welcome to the site. This is to add to what Ted has said regarding the 'Bird harmonic balancer.

IF the 1 inch cast iron spacer is in place between the water pump and the timing chain cover, it is likely that you have the original 'Bird vibration damper. As Ted indicated, the timing marks are on the pulley edge and cannot 'slip'.

In looking at a 'Bird damper on a newly purchased vehicle, it is worth checking the donut. The 'donut' behind the pulleys on these is very prone to moving back toward the timing chain cover. The rubber gets hard with time 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.

Also, between the 'donut' and the pulley are two 180 degree apart openings. The side of the openings closest to the 'donut' have center points that are closer to the 'donut' than the ends of the openings. Using an inside caliper, the space between the center of either of the openings to the face of the 'donut' should be between 5/16 and 3/8 of an inch. This dimension was taken from a damper I ordered from Ford that has not been used (yet).

Hope this helps. Smile
By Lex - 12 Years Ago
Thanks. It is a T-Bird damper. I personally havn't checked it yet so thats my next thing to do to make sure the previous owner didn't mark the pully wrong.
By ian57tbird - 12 Years Ago
Not sure if your issue has been resolved but I did not see anything mentioned about the woodruff key being installed or missing.

Just as a note, I had the problem of the weight moving back on my 57 T Bird. it took awhile to work out what the squeak was, finally found it, narrowing it down by listening with a flexible hose around the motor. Even stranger, it would only squeak when the motor was over normal running temperature (when waiting in traffic or alike) and as soon as the temp came back to normal the squeak would go. My theory on the squeaking when warmer was that the metal would expand just enough to touch as engine bay temp increase when stationary, and would shrink again as cooler air came past it after siting for a while with the motor not running or moving alone.
By NoShortcuts - 12 Years Ago
Hi Ian,

Welcome to the Forum.

Thanks for chiming in regarding your experience of having a little 'Bird make a chirping sound. I'm sure some wrote me off as having been out in the sun too long when I wrote about the crankshaft damper donut making contact with the front motor mount intermittently.

Regards,
By cos - 12 Years Ago
Hi Common problem on early birds. They can be rebuild. One rebuilder Email is sales@damperdoctor.com
By ian57tbird - 12 Years Ago
Mine wasn't intermittently. It was almost a constant squeak, but it only made a noise when it got over running temp.
By ian57tbird - 12 Years Ago
Back to the timing problem. Something simple, was the vacuum advance disconnected before checking?
By Hoosier Hurricane - 12 Years Ago
Does the timing advance when you throttle up the engine when checking timing with the timing light. If the advance mechanism is frozen in the at rest position, then manually advancing the timing to the point of spark knock would definitely make it run better on the road.