[DeTomaso] I need some advice from you Fordies

[jderyke at aol.com]

Well, to start with, they aren't 'first-class parts'. They're semi-roller 
rockers, possibly sized for a big-block Chevy since they use GM ball-pivots. 
Big-block Chev rockers will fit a 351-Ford but have a ratio of 1.70:1 rather 
than the 1.72:1 of 351/429/460 rockers, so cam lift is slightly degraded. 
Full-roller rockers have low friction needle bearings as pivots rather than 
balls. Ball-pivots may cause seizing and failure with stiff valve springs one 
needs for a performance cam. In one test, ball-pivot rockers, submerged in 
oil, galled and turned blue from friction in one dyno run. But it looks as 
though the engine has single valve springs (possibly stock).
Second, the engine is apparently using Ford (or Ford-type) paired pushrod 
guide plates, and on some combinations of heads, valves, pushrods etc, such 
paired guides must be cut apart, bolted down properly, then tack-welded back 
together again. Otherwise the alignment to the valve stems will be as you 
noticed, and this can cause pushrod breakage. Apparently, the rocker pedestals 
have been milled to Boss 351 specs to even use Ford pushrod guide plates. 
Otherwise, the engine would need Crane conversion guides with plastic pushrod 
grommets where the pushrods rub them.
Third, I can't tell from the photos, but all-steel pushrod guides need 
hardened steel Boss pushrods or they will wear at the point where the guides rub 
them. Try lightly running a small file over the exposed sides of the 
pushrods; if they're hardened, you won't be able to mark them at all. If they're 
std pushrods, the file will easily cut them. With unhardened pushrods, it 
doesn't take long for hardened guides to wear clear through the pushrods and 
cause breakage.
Finally, I personally would change to full roller rockers to get the low 
friction benefits. Those semi-rollers won't help performance much- even if 
they are 1.72:1 ratio. 
if you want to retain what you have right now, and your pushrods are 
hardened, you can correct the bad geometry by cutting apart the guides that have 
obvious interference and leave them separated, then reinstall properly. Next, 
heavily mark the valve stem ends with a magic marker, let it dry and rotate 
the engine two full revolutions. With a magnifying glass, examine the marks 
the rollers left in the magic-marker. There should be a narrow line across 
the exact center of each valve stem. If the line is offset very far from the 
stem center, you can vary either the stem length (by welding to make it 
longer or grinding to make it shorter), or change pushrod length (by replacing 
them with longer or shorter ones), to correct this. But of course, the 
rocker's alignment to the valve stem must first be fixed by altering the guides.
Some cam grinder's tech sites have more info (and maybe are clearer than I) 
on this vital geometry correction. Its a bunch of work, which is why pro 
engine builders like D Drenske and Russ Fulps spend hours of their labor 
getting this stuff correct.   Good luck- J DeRyke