Engine Vibration

[Grantiz84]

ok so when I first start my mustang the motor run smooth with no issues, but after the car runs for about 30 to 45 minutes when I bring it back to idle I have a engine vibration that slightly shakes to whole car. what could cause a vibration only at idle and only when its warm? I can't feel it when I start driving again and don't notice any power loss.

its a 302 that has been refreshed just did a 6cly to V8 swap.

Thanks for your time
Grant

 

[PoppyMod]

Hi Grant,
What generation 302? (pre/post emissions)
What is the idle speed? (If C4, idle speed in "D")
General tune of the engine? (plug gaps, point setting, timing, wires etc)
Engine vac readings?
Condition of the motor mounts?

 

[Flying Dutchman]

I have seen something like that in harmonic balaners changed only in idle will you notice it you might want to ask about that