1978 F250 with a 1984 351W in it. Truck is a 4-speed and has a bad vibration in it at idle, but it smooths out as soon as you put truck in gear and drive. Could it be the flywheel?

Thanks
Frank

 

Could be a few things. First thing that comes to mind is that your idle is set to low. How does it run, any lag. It could also be a improperly gapped plug or bad wire. These are the easy fixes. I am guessing you are working the trottle from the engine and can see that non of the engine mounts are broken. Check the trany mount also. My guess is the timeing is a little off. Hope that helps

 

Thanks for the tips!

 

Let me know if you figure this out.. I am having the same issue. 1978 Bronco, 400. BAsically new everything, machined etc.. Recently had ground issues (chassis to block, starter cable also) got burnt too close to my exhaust, re routed and replaced.. Replaced solenoid recently, and ever since i swear my motor acts like its miss tuned at the carb, its just real shaky when you know it is supposed to be smooth.. Battery, cables, all that move more than normal and i hear my pip rattling against my transmission mount under my feet, so annoying, and makes me feel sad to hear it. I tried tuning, messing with timing (Which is 6degree perfect start up before this happened) and checking ground cables again.. Well, I pulled the distributor cap off )replaced msd about 2 months ago) and underneath was a nice burn mark on my center rotor piece. Under the cap straight above that, is a "burn" black mark in the center also. What could cause this? And i havent tried cleaning it yet but do you think it could cause a messed up idle? Its rough, rattly, vibration in the steering wheel.. completely smooth on the highway and driving period. ONLY idle. help... thank you