engine vibration

F

fast fredy

Senior Member
Morning guys .. On my stock 55 272 . I have a slight but noticeable vibration at about 2000 rpm .. Its not driveline related because it doesn't have to be moving, I can feel it thru the steering wheel . I put some extra rubber under the steady rest , thinking it could be metal on metal , but no joy .Engine mounts seem OK .. The funny thing is that I loosened off the transmission mount bolts and unless its my imagination or wishful thinking , it seemed to be much better Any thoughts? thanks Fred
 
Two initial guesses...
If the engine has a front crankshaft pulley with a rubber mounted damper ring, the rubber layer could be failing and the weight ring may have shifted.

Does it have an automatic transmission? The rivets on the flex-plate holding the tabs to the torque converter can loosen, causing problems.
 

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Possible ignition points fluttering under the higher RPM's. DO NOT ever loosen the inner nut against the nylon insulator on the points because this nut holds the spring tension on the point arm. Easy fix though, just get a replacement set of points (I suggest Echlin #CS754 from NAPA). They are made in Mexico.
If nothing else, check engine manifold vacuum at 2000RPM's and see it it isn't dropping off at higher RPM's. If so, carburator gasket, loose vacumm line or cracked hose?
PS; It is my experience that when the original Fordomatic flexplate rivets loosen up, it doesn't cause engine vibration, but they will make a lot of noise.
 
fast fredy said:
standard transmission, thanks I'll look at the crank pulley , any obvious way to tell by looking thanks Fred
Click to expand...
The weight ring may creep toward the rear, off of the center hub. The rubber layer will get dry & crumbly. Similar to this example photo.
And / or the TDC mark on the outer ring of yours can be no longer at actual cyl #1 TDC due to the ring twisting out of position.
.
 

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Only have about 100 miles on it since I got it on the road , engine is stock . I first thought it was the old bias ply tires , but still thereafter new radials ... I will check to see if it goes away with clutch pedal down thanks Fred
 
When did this problem start? Is this car a recent puchase? I had a similar vibration problem 20 years ago w/a '72 Mustang 351C restoration that I just completed. It drove me nuts! I came to the conclusion that it was a ballance problem. Took the new flexplate I got from Summit to a good engine rebuilding shop, to check the ballance. Sure enough, it was out of ballance. They fixed that, and my vibration problem was gone. - F f
 
Thanks FF .Mine is manual , but I guess flywheel and or pressure plate could do similar As I mentioned earlier it seemed like if I loosened bolts on ****** mount it seemed to improve ... I might try this again to see if it was wishfull thinking Fred
 
As I mentioned earlier it seemed like if I loosened bolts on ****** mount it seemed to improve ... I might try this again to see if it was wishfull thinking ...
Click to expand...

Remove the mount and see if it is separated.

Is this a fresh engine or was in the car when you bought it? Need some engine service history.
 
Any chance you have removed the fan belt and run it up to 2000 for a few seconds to check if vibration still there? Just a thought.
 
fast fredy said:
original engine .. only had the heads off for gaskets ( engine not removed)
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Two spark plug wires were accidentally swapped? They can be hard to follow thru the original style looms.
 

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I only had it fired briefly , enough to see it needed head gaskets , so I don't know if vibration was there before gaskets Fred
 
Pressure plates are always a sore spot when it comes to vibration control on an engine. After that would be the clutch disks but those disks can be isolated from the engine by simply disengaging the clutch while the engine is running and bringing the engine rpm up to see if the vibration still exists or not.
 
When you installed the heads, did you find true No.1 TDC on the balancer to adjust the valves?

If not, I would start by finding true No.1 and verify the integrity of the balancer. You would then go from there (valves - IGN) if still vibrating.

You said you shimmed the ENGINE STEADY REST. That piece only centers the location of the engine to the frame. It carries no weight. If the insulators are good, and the engine is sitting correctly in the cradle (incl. trans mount), it should attach the the front cross-member easily. Is the front cross-member intact (no rust-out)?

If all of this fails, then possibly pull the trans and pressure plate to see if that corrects it. After that, there may be something wrong in the engine.

I would put a manifold vacuum test gauge on the engine first to possibly save time and $$$.

Keep us up on it as I will learn something off this exercise ... ;)
 
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