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1964 425 motor vibration - last ditch effort


R8RS
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I have already gotten advice on this topic, for instance, flexplate in proper position, harmonic balancer, and so on.  But I am going to try one more time, just in case there's some longshot at a fix.

 

I bought my 64 Riv a few years ago and the motor ran but needed a rebuild for sure, so I had it rebuilt.  Prior to the rebuild, there was a motor vibration, so I thought once it's rebuilt, the vibration will be gone.  Well, that's not the case.

 

I am down to... do I send it out to Centerville Auto Repair over the winter to have it pulled apart and rebuilt again?  Or is there something I am missing?

 

I'm not made of money, but I also want the motor to run vibration-free.

 

We have ruled out drivetrain, etc., it is definitely the motor.

 

Thank you!

 

Steve Napoli

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Steve what is the severity of your vibration? Is the whole car shaking? If you put a cup of water on the dash is it spilling or is it a ripple? all the nailheads I've owned have a jiggle here and there. They are not modern day engines.

 

Steve 9236

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Tom, we did remove the fan belts & run the engine, and it still vibrated.

Steve 9236, not to sound funny but the severity fluctuates.  I am going to take a look and make sure the harmonic balancer is not a 364 and that it definitely is a 401/425 balancer.  Pretty certain, but just in case.

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Hi Steve,

 

  Did you have the motor balanced in the rebuild?

4 hours ago, R8RS said:

I have already gotten advice on this topic, for instance, flexplate in proper position, harmonic balancer, and so on.  But I am going to try one more time, just in case there's some longshot at a fix.

 

I bought my 64 Riv a few years ago and the motor ran but needed a rebuild for sure, so I had it rebuilt.  Prior to the rebuild, there was a motor vibration, so I thought once it's rebuilt, the vibration will be gone.  Well, that's not the case.

 

I am down to... do I send it out to Centerville Auto Repair over the winter to have it pulled apart and rebuilt again?  Or is there something I am missing?

 

I'm not made of money, but I also want the motor to run vibration-free.

 

We have ruled out drivetrain, etc., it is definitely the motor.

 

Thank you!

 

Steve Napoli

Steve,

 

  Did you have the engine balanced when it was rebuilt?

 

Tom

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Hi Tom - I trusted my mechanic in that it would be done correctly, but in order to balance the motor the machine shop would also need the crank, correct?  The crank stayed at my mechanic's garage.

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I recommended putting an oscilloscope on it to watch the secondary ignition. I don't see the results of that listed in the things done. There were a couple of checks for valve stem play as well.

They are valid tests from my own experience.

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IF the crank stayed with your mechanic I don't care IF the rods & pistons were balanced properly then the crank is more than likely causing your problems.

Not saying it is, BUT most certainly is/can be a problem???

At this point you are just chasing your legs. Might as well start the planning of engine removal & properly getting things done. Were pistons replaced??? Engine bored???

ANYTHING else we should all know instead of just chasing theory's???

 

Tom T.

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Just now, R8RS said:

Tom, yes it had to be bored .040 and I bought an entire Egge rebuild kit, so it was all done fresh.

Steve,

  Your mechanic dropped the ball on this...especially since there was a vibration before rebuild. Yes, a vibration could have been caused by a power imbalance before rebuild but it is standard practice to have the engine balanced when changing pistons...and especially so if there was already a vibration concern. Just my opinion..

Tom

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makes sense, Tom.  I know he tried to make it as inexpensive as possible for me and that's probably why he figured the crank didn't need to go to the machine shop.  And here we are.  Thanks for your help to everyone!

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Not too far. I get up to the old Carrier Circle once in a while to catch up with some business associates. Is the Liverpool in the background of your picture?

 

On the vibration, I look at the engine as 8 individual cylinders that must all operate at very close to the same combustion/volumetric efficiency for them all to be in sync . The primary step is to assure that is happening. One bad note in the orchestra will affect the harmony.

 

Even a test as simple as comparing the secondary voltage on each plug wire will give some insight.

 

I had a 350 Buick with a slight roughness one time. One plug was taking an extra 300-500V to fire, turned out the manifold runner was the one with a vacuum port and the rubber hose was cracked, not broken and visually looked good. But was leaking enough air at 18" to lean that runner out. I was #3 diagnosing that one and it went home smooth.

 

Test those things you can test and verify. Try not to make assumptions and verify the assumptions. It can mislead you.

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1 hour ago, 60FlatTop said:

Try not to make assumptions and verify the assumptions. It can mislead you.

I interpret Bernie's recommendation to mean that you shouldn't assume the engine vibration you're chasing today is the same one the old engine had.  With that in mind (and expanding on Bernie's leaky vacuum hose) are you sure that there isn't a vacuum leak somewhere?  Check intake manifold gaskets, vacuum hoses, diaphragms and accumulators (disconnect and plug accessories one at a time).  Have you checked your power brake booster diaphragm?

 

Make a list and check each possibility.  You may still wind-up pulling the engine, but at least when you do it you'll be certain that it's not an Easter egg hunt...

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