Mailbag: Curing Unwanted Vibration in a 5.0L-Powered ’66 F-100 Pickup
(Image/ClassicRoad.com)
Q: Help!
I have a 1966 Ford F-100 pickup with a transplanted 5.0L from a 1991 Mustang and the following mods: Ford Performance cam (220° duration/.498″ lift), Airflow Research CNC-ported 185 cylinder heads, Edelbrock Performer intake manifold, Holley 600 cfm carb, B&M flexplate with a 50 oz. balance, TCI C-4 Street Fighter transmission, and a TCI 10″ Street Fighter torque converter.
The water pump, pulleys, and damper are from a 1969 Ford 302. I am experiencing a sporadic vibration between 35-55 mph when driving and in neutral or park when the engine is revved. I can feel it in the gas pedal, steering wheel, and seat. The vibration goes away when I lift off the throttle. My mechanic claims to have sent the engine out to be balanced during assembly.
I believe something is out of balance or the torque converter is bad. Can you help?
A: We promise to try!
We think the problem is the balancer. In 1981, Ford changed from a 28 oz. to 50 oz. imbalance.
To fix the problem, simply use the original balancer from the 5.0L engine, or an equivalent replacement, and you should be good to go!
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I had the same problem when I put together my 65 Mustang. I dropped in a mid 80’s 302 in place of the original inline six. I used the factory 50 oz. balancer and the 28 oz C-4 flexplate not realizing at the time that they were not compatible. Talk about rattling the fillings out of your teeth. Stick with the factory balancer. B&M makes the flexplate for the C-4 that’s balanced to match the later model 50 oz 302 harmonic balancer.