1500 engine vibrates

[donandmax]

Removed my engine in order to check the clutch. Re-installed it and the starter. Turned the key to make sure the starter was working the engine immediately fired up. I immediately shut it off because I remembered I had drained the oil and it had none in it. The engine ran for maybe all of one second. My mechanic tells me probably no harm done.And yet I have a bad vibration at around 1500 rpm.above that the engine is smooth and oil pressure OK.The engine vibrates in neutral and while in gear so its not the drive line.I hear no knocks. But I'm thinking possibly a main bearing. Anybody got any ideas of what this could be ? The motor mounts are tight and OK.
Thanks, Don McQueen
1979 Midget 1500 eng.

 

[jlaird]

Well if it ran for one sec or even 5 sec you did not hurt it.

Check carb for fuel mix. for the vibration.

 

[donandmax]

Thanks Jack I was thinking carb also. But would it not vibrate @ other rpm's below 1500. Idles pretty good (850 rpm) Thanks anyhow

 

[blkcorvair]

What type of carb. My weber gave me this exact same feeling when out of tune.

 

[jlaird]

Not necessarly Don. When carbs out of tune you seem to get a rough spot or area in my experience. Of course when full open all is well.

 

[donandmax]

Scott, car has a Zenith Stromberg. I tried adjusting but vibration is still there. I never had the problem before I pulled the engine (and did nothing to it) This is one of those misteries that will probaby never be solved.

 

[jlaird]

Have you checked carb intake for an air leak?

Is the vacumn advance hooked up? Ahhh, 1500 RPM look at the this line closely.

 

[donandmax]

Jack, yes to all

 

[SilentUnicorn]

Did you hook the steel cable back up to the bell housing? It is on the passenger side and runs from the cross member to the bell housing. The tightness of this cable, of lack of could cause a vibration.


mark

 

[donandmax]

Mark, I'm sure its hooked up. But I always wondered what that cable is, so what does it do ?

 

[SilentUnicorn]

Best i can tell is it helps keep the engine from twisting. I do know that if too loose the car will seem sluggish and if too tight it can cause vibrations that will drive you nuts.

it was just a shot in the dark.


mark

 

[texas_bugeye]

Stuck advance wieght? MaYbe pulling the engine or replacing it dislodged some dried grease or filped a spring ?
Just a thought.

 

[GTsRFine]

My guess is that something is out of balance with the clutch/flywheel. When you press the clutch pedal down slowly, can you tell a difference in the vibration?
The only other thing I can think of is motor mounts but you say you have checked those. It wouldn't take but a minute to verify block-mount and mount-body bolts and look at the rubber in the mounts very closely.
I hope it's something simple and cheap.

Edit - what about the transmission mounts?

 

[LarryK]

The flex cable is not only a ground link between the engine and transmission but a crash unit deflector. Makes the engine and trans move a certain way on impact. As for vibration on a clutch pull and inspect. Did you mark the relation of the clutch assembly to the flywheel? Sometimes these are balanced as a unit then mounted, then marked, seperated then remounted. In the older cars the crankshaft is balanced with the fly wheel and the clutch assembly balanced with the flywheel and then assembled. Might be original, might have been redone and in perfect balance. Not seen alot but just a thought!