engine viberation

[jonesmerc]

Bought a 48 Plymouth first week in December 2013. Needed an engine rebuild,brakes, etc. Well shes all back together now and I took her out this week-end. After a 60 mile round trip the only thing wrong is a slight viberation seem at all speeds. I have elimanated the drive shaft as with the clutch depressed its as smooth as could be. Sitting at a stand still and bring the RPMs up she viberates. Driving down the road she viberators. Any ideas where to start looking?

[desoto1939]

When you did the engine rebuild did you install allnew motor and transmisson monuts?  Since you probably had the originals in the car these would have dried out adn the trans rea upper and lower probably  would have colapsed.

 

That would be the first place to start>

 

Also not sure but does you engine have a vibration dampener or harmonic balancer as part of the lower pully down near the timing mark.  This also might need to be replaced since the rubber inside the unit dries out and then you also get vibrations.

 

Rich HArtung

Desoto1939@aol.com

[casper50]

Harmonic balancer as Rich mentioned.

[Dave72dt]

Simple things first.  Recheck your firing order.  It's easy to stick a plug wire on the wrong plug after it's been apart for a while.  Check the timing and the vacuum advance, vacuum leaks.

[Don Coatney]

I agree with Dave72

 

What brand of spark plugs are you using?

[Lumpy]

Assuming it has new plugs and wires? Might want to check the gap on the plugs. If you have the plugs out anyway...why not check the compression? And that might lead one to re-check the valve adjustments. ?? Then you have eliminated all those unlikely, but possible possibilities. Then start looking at the balencer.

 

Having a balance (or is it balence?) problem can really be a pain...I chased a vibration around on my '72 Dart for years, never did find it. Then I took the 318 out and put in a 360, and that fixed it. But on the 318, I changed dampers, alternators, drivelines, trans tail shaft, you name it, never could get it. And on the 360, I used the same driveline, converter, etc., only difference was the flex plate. It wasn't real bad, just annoying. Hopefully you don't have anything actually out of balance.

 

Does kind of sound like one of the cylinders is not firing strong for some reason, and or, as mentioned, sometimes crossed plug wires won't be real obvious, the engine will run almost normal, but not. 

 

ken.

Edited April 22, 2014 by Lumpy

[jonesmerc]

Well, I checked the plug wires, adjusted the valves, ran the engine without the fan/starter and still the viberation. Motor mounts are new. Help

[William Davey]

Remove the trans, clutch and pressure plate then run the engine.  I had a new pressure plate that was severely out of balance on an old F__D pick up back in the day.  The thing would get worse as RPM's rose, but the vibration was always there.

[Dave72dt]

I have elimanated the drive shaft as with the clutch depressed its as smooth as could be. Sitting at a stand still and bring the RPMs up she vibrates. Driving down the road she vibrates.

Clutch depressed it's smooth when bringing the rpms up? Trans in neutral, clutch released it vibrates as the rpm's come up. Clutch depressed takes out everything from the clutch disc back. In neutral, disc and transmission come back in to play. Gears, shafts and brgs are still turning even if the driveshaft isn't when in neutral and the clutch is released.