(NEW) Engine Vibration

[luke-ao]

I'm getting a vibration on low-midrange RPM sitting and driving. The vibration is easy to pick-up but I wouldn't say it's extreme, but it's definitely noticeable and enough that you wouldn't ignore it. When driving the vibration starts just before it shifts to second, and mostly smooths out to a very slight almost hard to pick up vibration at about 55+ mph, but I can still detect it.

Back story is, it's a fresh built 302, new cam, lifters, push rods, timing set, rings, bearings, pistons, fresh built heads, new harmonic balancer, torque converter and flex plate, new intake, new 625 Demon carburetor and distributor. There's 550 miles on the build. I dont know the previous history of the engine I purchased it at an auction, but I did rebuild it myself (not my first).

Basically everything is the same from the Trans back, I did pull the driveline for the engine swap because I pulled the trans to clean it up, but nothing was changed on the drive line, and I didn't have the vibration prior to the engine swap. I'm pretty sure the vibration is with the engine because sitting in park and reving the engine you can feel the vibration.

It runs really good, good vacuum, timing set at 12* initial and 32* max and to the best of my knowledge the carb is dialed in (Adjusted with vacuum and rpm gauges)

Not sure what to look for at this point, any ideas?

[sargentrs]

Did you replace the motor mounts? Transmission mount? Check the torque on those bolts?

[ddcrim]

Harmonic balancer ? The rubber has been known to deteriorate.

[tnlprt]

Are you sure the dampner and automatic flywheel are the correct ones for your rotating assembly

[luke-ao]

I did install new motor and trans, everything is definitely tight.

[luke-ao]

A new harmonic balancer and flex plate was installed.

These were my first thoughts, but as I understand it, if they were 50oz on a 28oz engine it would shake itself apart right away, I do have 500+ miles on the engine.

Is this a wrong assumption?

[cep62]

Did you check your fan blades?

Take your belts off and see if it still vibrates.

Are you sure it's not a miss? crossed plug wires? miss adjusted valves ?

Did it shake from initial start or come on gradually ?
The wrong flywheel will show up right away.

[luke-ao]

Electric fans.
I dont think its a miss, the engine runs like a top.
Valves were adjusted on the engine stand.
Vibration was there from the start.

[sargentrs]

Did you, by chance, replace u-joints or, if it's a long bed, separate your rear driveshaft from your center driveshaft? You may have inadvertently gotten your driveshaft out of "phase". The u-joint's yokes are supposed in line with each other. If they were before but aren't now, that could cause a slight vibration.

[jzjames]

Harmonic balancer ? The rubber has been known to deteriorate.

My inline six recently acquired a vibration like you speak of. Looking at the harmonic balancer, and it almost looked like it was wobbling a bit. Asked my friend and he said if it was wobbling then oil would be pouring out of the bearing.

[luke-ao]

Did you, by chance, replace u-joints or, if it's a long bed, separate your rear driveshaft from your center driveshaft? You may have inadvertently gotten your driveshaft out of "phase". The u-joint's yokes are supposed in line with each other. If they were before but aren't now, that could cause a slight vibration.

I did not replace u joints but did separate the two drive shafts. Isn't there a key way that only allows it to be 'splined' (not sure that's an actual word, ) in a single orientation? I'll certainly consider that but I do get vibrations in part while reving the engine.

How do you go about getting the u-joints back into proper phase?

[luke-ao]

Harmonic balancer ? The rubber has been known to deteriorate.

My inline six recently acquired a vibration like you speak of. Looking at the harmonic balancer, and it almost looked like it was wobbling a bit. Asked my friend and he said if it was wobbling then oil would be pouring out of the bearing.

Actually looking at the harmonic balancer and the pulley it does look like it is wobbling but its brand new purchased for this build. I was going to remove all the belts and the pulley and see if that helped. I was thinking maybe the balancer was bad because it was probably made in China(??)

[jp2005]

Harmonic balancer ? The rubber has been known to deteriorate.

My inline six recently acquired a vibration like you speak of. Looking at the harmonic balancer, and it almost looked like it was wobbling a bit. Asked my friend and he said if it was wobbling then oil would be pouring out of the bearing.

Actually looking at the harmonic balancer and the pulley it does look like it is wobbling but its brand new purchased for this build. I was going to remove all the belts and the pulley and see if that helped. I was thinking maybe the balancer was bad because it was probably made in China(??)

Keep us updated,I'm curious.

[sargentrs]

How do you go about getting the u-joints back into proper phase?

Phasing your u-joints just means lining up the yokes in the same orientation. Like this.

[DuckRyder]

Didn’t 302/5.0 change balance factors? All the parts for the same motor?

Where the driveline is concerned, though it won’t cause vibration when revving, make sure the angles at the rear of the transmission and the piñon are the same, there are wedge shims for the axle to correct if needed.