250 - rattles my teeth!!! any ideas why?

[Anonymous]

i've got a 250 in my '65 and it idles great and seems fine on the top end of the RPM.
BUT...
while driving or sitting still out of gear, there is a quite noticeable vibration that comes in and out at about 200 (guessing) RPM's.

is there any thing habitual about these engines that causes this?
like a harmonic balancer going south?

the car had so many other issues on it when i got it, i'm just now bringing this one up.

Thanks all!

 

[addo]

Could you have the wrong flywheel or flexplate in it?

 

['61 Draggin Wagon]

maybe you have metal to metal contact somewhere? like a bad motor mount? Or exhaust touching the floor/body?
Darryl

 

[matt1967]

if it's using a V8 flywheel/ flexplate, they are balanced at 28oz or 50oz, that counterweight needs to be removed, if that's what it has. our 6's are neutral balance.

 

[Anonymous]

thanks all.
i actually meant to say 2000 RPM. (not 200)
i'm not sure what flywheel is in it... good start though.
from the looks of it, the PO pulled the eng/trans out of a mid 70's car so i'm thinking the flywheel is good... but when dealing with PO's "issue" you never know what you are gonna get!
it could probably use new motor mounts too.

 

[Bort62]

Something I have discovered is that if I have too much advance at low RPM, it causes the engine to vibrate like a mofo.

This seems particular to the L6, and I am not exactly sure why. I'm sure someone here can shed some light.

But you might want to try backing your timing off a little.

 

[mustang6]

Have you done a compression test? I have felt engines behave like this when they have a burned valve or something else that caused one or more cylinders to be "dead".

 

[Anonymous]

MORE GOOD STUFF TO CHECK.
THANKS!

 

[66200i6]

Ya, never said if your running a std or auto trans.

I have seen the gear on the torque converter for the auto come loose. You may be able to see if this is the case by removeing the inspection plate and having someone turn the crank by hand at the pully. There are a number of tack welds attaching the gear to the outside diameter of the converter. Look for a weld that has become detached.

Good luck, Ric.

 

[Anonymous]

sorry...
its a 3 spd.