Another engine vibration

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Offline minipete

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Another engine vibration
« on: November 26, 2021, 05:27:54 pm »
I have a slight vibration in my 64 with 289, top loader.  Engine (refreshed 30 years ago and not been apart since) is pretty stock and has always been smooth.

I can feel the vibration in the body of the car, even when sitting in neutral and revving the engine.  Engine runs and drives fine.

It starts at 1500 rpm and get worse as the revs rise.  Pushing the clutch in doesn't change it so unlikely a gearbox issue.

If I hold the gearlever the level of vibration is no worse than the what I feel in the body.

I am not sure if this is a normal vibration and now it is somehow transferring to the body or if it is a new vibration in the engine.

I recently pulled the shifter apart and to get access I took the gearbox mount off so that was my first suspect, I loosened off the mount and nothing changed.

I rehung the exhast as the mounts were old and stiff (like me).  No difference.

New engine mounts in, no difference.

Pulled the fan belts off to isolate the generator, water pump and PS pump, no difference.

I have done a close check all along underneath to see if any part of the driveline is touching the body, none that I can find.

Harmonic balancer looks fine, could there be an issue that you can't see from the outside?

I have checked the exhaust temps of each cylinder and engine is firing on all cylinders.  I fitted new plugs.

I have read all the previous posts on vibrations and none are like mine.

I have run out of things to check.

Any ideas anyone?

Offline Clubman7

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Re: Another engine vibration
« Reply #1 on: November 26, 2021, 07:50:07 pm »

Offline minipete

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Re: Another engine vibration
« Reply #2 on: November 26, 2021, 11:30:33 pm »
Thanks for the link but I had read that one.  Mine is manual so no flex plate.

It has had the same engine/clutch/gearbox since the mid 70's and has run smooth for 45 years so setup isn't a problem, something has happened recently to cause the vibration, but what?

Offline Reborn67

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Re: Another engine vibration
« Reply #3 on: November 27, 2021, 07:57:38 am »
Hey minipete, sounds like you have been quite thorough, not being familiar with a toploader myself, have a couple of general ideas, does the bell housing have an inspection cover so you can see the flywheel and clutch, and see if something has come lose or broken, does a flywheel have a counter weight like a flexplate? The pressure plate assembly will rotate regardless of pedal position and any imbalance in this will effect the engine,
Curious to see what you come up with, good luck, Andrew..,


Offline minipete

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Re: Another engine vibration
« Reply #5 on: November 27, 2021, 10:42:58 am »
Hey minipete, sounds like you have been quite thorough, not being familiar with a toploader myself, have a couple of general ideas, does the bell housing have an inspection cover so you can see the flywheel and clutch, and see if something has come lose or broken, does a flywheel have a counter weight like a flexplate? The pressure plate assembly will rotate regardless of pedal position and any imbalance in this will effect the engine,
Curious to see what you come up with, good luck, Andrew..,
Can't see inside the clutch housing unless I go in through the the clutch boot with an endoscope.  If something had broken in there I would expect some untoward noises unless ther eis enough clearance in the bellhousing for it to sit at the bottom and not get hit by the flywheel.

I feel like something must have moved or broken somewhere.

Pete


Offline minipete

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Re: Another engine vibration
« Reply #7 on: November 27, 2021, 04:27:12 pm »
I put a big screwdriver in between the balancer and the belt pulley and couldn't get any movement from the outer ring, alignment of outer to inner looks good.

I had a balancer fail badly on my Corvette and it was very obvious but this one seems alright.

Offline minipete

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Re: Another engine vibration
« Reply #8 on: November 28, 2021, 11:01:06 pm »
check your spark plug leads put a new set on if you  have a set it is possible leads can brake down when hot/under load which  can cause a miss fire in a cylinder hence the vibration , also when the car is vibrating pop the bonnet at night  when dark give the engine a slight rev from the carby and see if you see any spark jumping across the coil area , also try another coil as they can play up when hot .

Car had Pertronix distributor, Flamethrower coil and new leads fitted 3000 miles ago, I will check just in case.

Ignition breakdown usually accompanies a loss of performance, the car accelerates normally, just vibrates.

Offline minipete

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Re: Another engine vibration
« Reply #9 on: November 28, 2021, 11:02:22 pm »
also try pouring water over your inlet manifold where it meets the cylinder head areas and the carby base gasket area and any vacume hoses that you may have on the manifold if the idle speed changes then you have a air leak which can also cause a engine vibration , this water test must be done with the engine on , also check your dissy cap isnt cracked or faulty , rotor button , points condenser etc

I would expect a vacuum leak to show a loss in performance too, still it's another thing to try and I am running out of options.

Offline minipete

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Re: Another engine vibration
« Reply #10 on: November 29, 2021, 05:40:10 pm »
I checked the timing today.  It was set at 11 deg BTDC 7 years ago and not altered since.

It now reads 20 deg BTDC.  The car still runs perfectly and I would assume at 20 deg I would get some kick back on the starter (it doesn't).

This is suspiciously like the outer ring on the balancer has slipped about 1cm.  Probably enough to make a vibration.

I can't get a good close look at it so will pull it off and inspect.

Thanks Sam for the call.

Offline minipete

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Re: Another engine vibration
« Reply #11 on: November 29, 2021, 07:00:51 pm »
Pulled the belt pulleys off and the balancer looks fine.

No sign of perished rubber and the outer ring is solid as a rock.  I'd happily replace it if I thought it would do any good.

Also the balance weights are on the inner ring so if the outer slipped it should not cause a vibration unless it was severely misaligned (it's not).

I marked where the key is in comprison to the TDC mark in the hope of finding a photo on line for comparison.

Pete