351w f100 swap

[Allendb72]

Hi, I just recently built my first 351w it is a 1996 f350 5.8 with new rod bearings, main bearings, rings, lunati bare bones cam, hei style distributor, Holley 4 bbl, older/bigger valve heads. I attempted to break it in today. It was all going really good until about 5-10 minutes in when it started to clatter really bad so I shut it off right away and pulled valve covers and all rocker nuts were at the top of the studs. So I re set all the valves let motor completely cool off and re fired worked great until 5-10 minutes in and the same thing happened. How are they loosening. Is the cam killing its self? Are lifters wearing? Just wondering where I screwed up.

The motor is going in a 72 f100.

[fatheroftwo]

Sorry no one responded. I'd guess you need self locking nuts.

[Fellro]

I am not familiar with that year, so help me out a bit. Did it already have the studs and nuts, or did you add them? I am used to the preset kind that has its own pivot pedestal. If the nuts are not the original, be certain you have lock nuts on there. They shouldn't be backing off that easily.