hello all,


I have a 1978 E-100 V8 Van- i got it for free non-op - been working on it/ learning about it in my yard - and just got it running and had a key made etc.

it drives good- but on the highway at certain points it starts to knock - its rapid fire knock-knock-knock and gets louder and louder- I can make it stop by either backing off on the Gas pedal- or flooring it and accelerating very quickly-? this is all while going 50-70mph- 4th gear? lower speed than 50 = no knock, although the spedo is broken so i don't know exactly how fast i am going-

?