Nick3367

I would appreciate some help...
1965, Auto, 200ci that has uneven vibration at idle, but, goes away at higher RPM. Have done the following:
Valve Job (had rockers Professionally adjusted), rebuilt Holley 1barrel, New plugs, wires, points & condenser, rotar button, distributor cap, vacuum line, fuel line, pcv. Good Vacuum. Vacuum advance diaphram works.
Before having a garage adjust the rockers, I noticed that some of the lifters were soft and seemed to collapse (a gap appeared between the push rod and the rocker) under pressure if I leaned on the wrench too much where as others did not.
The lifters don't tick or make noise, but, could some be weak and not opening a valve or two, thus, causing a vibration at idle.
I've had the car to two garages and enlisted my gear head friends with no success.
Thanks for your help!

dklistul

My first guess for any rough idle? Vacuum leak.

I know you said your vacuum is good but a small leak can cause a rough idle without affecting the vacuum reading much.

Gun Jam

Uneven, rough or vibration at idle can also be caused by a misfire or completely dead cylinder. If its weaker than normal under load Im betting a cylinder (OR two) isn't firing at all.

Start it up when cold and use an IR temp gun to measure the temp of each exhaust header pipe look for cold ones (example: 550f, 480f, 500f, 590f, 200f, 485f) If you see something like the example then you investigate why cylinder 5 is at 200f)

If you dont have an IR temp gun now you have a good excuse to get one.

-Gun