Vibration Imbalance @3000rpm

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69cudaownr

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Location
Waterloo, Ontario, Canada
Guys,
318 engine with upgrades heads, intake etc. When I had a 904 behind it there were no problems. When I switched to a 833 4 speed I am now getting balance issues.
1. I checked both and replaced one engine mount.
2. I had the driveshaft shortened and balanced by "the guru" in our area.
3. the imbalance is present in neutral

I'm guessing I have three things to consider;
1. the flywheel
2. the pressure plate and clutch
3. the transmission input shaft
Everything related to the transmission was bought used and I do not know their history.
My question to the experts is what would you consider first? What can I test?
 
Vibration in neutral generally points to engine issues, as you know.
Things to consider:
Flywheel balance- you did use a neutral balance flywheel, not an externally balanced one off a 360 or '73 ish 340, right?
Note the balancing holes-
External:
OIP.jpg

Internal:
Picture062.jpg


You did install a pilot bushing/bearing, right?
You did check crank counterbore depth to ensure trans input shaft clearance, so it isn't binding or putting pressure on the nose of the input?
Make sure all flywheel/pressure plate bolts are tight...
As a last resort, you may have to put a dial indicator on the bell to check concentricity with the crank flange...
 
Last edited:
Vibration in neutral generally points to engine issues, as you know.
Things to consider:
Flywheel balance- you did use a neutral balance flywheel, not an externally balanced one off a 360 or '73 ish 340, right?
Note the balancing holes-
External:
View attachment 1715597643
Internal:
View attachment 1715597644

You did install a pilot bushing/bearing, right?
You did check crank counterbore depth to ensure trans input shaft clearance, so it isn't binding or putting pressure on the nose of the input?
Make sure all flywheel/pressure plate bolts are tight...
As a last resort, you may have to put a dial indicator on the bell to check concentricity with the crank flange...
 
I need to check on the neutral balance flywheel. I definitely don’t recall the “external” appearance but the “internal” appearance looks familiar.
The bolts are tight and shaft clearance good.
I’m beginning to think I have the wrong flywheel.
 
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