Repair or Replace?

[cjshaker]

The shafts appear to be OK but there is some bushing wear indicated in just 600 miles/21 hrs run time. If I'm going this far, $300 for new shafts might be cheap insurance. I'd also feel a little more comfortable with the sizing between Sharp shafts and Sharp Rockers.

I can't comment on geometry because I've never used PRW, and never will, but bushing wear does not mean the shafts are bad. Check them out. Some light scuffing or signs of use on the shafts really won't matter, as long as there's no heavy scoring or "lip" where the rocker was riding. The bushing is the wear item here. But if they are PRW shafts, and there is signs of scoring, it could be cheap material used in the shafts, or too tight of a clearance, not allowing oil to flow between them.

Buying Harland Sharp shafts does not automatically mean the shafts are the perfect size for their rockers. In a perfect world, things go together perfectly. We don't live in that world though. The last 2 sets of HS shafts and rockers I used were too tight, and would have wiped out the bushings in short order by not allowing enough oil to lubricate. They must be checked for size. I ended up having to use a brake hone on the rocker bushings to open them up about .001. From the factory, they had to be twisted on the shafts and had resistance to turning. Way too tight! Never take anything for granted.

I know it sounds like a lot of work, and I suppose it is (more time than actual work), but they need to be right. Too loose and you'll lose oil pressure and flood the heads. Too tight and they won't lubricate well and will eat the bushings and shafts up, if not completely seize on the shafts and start bending pushrods.

[shady]

same here, I had to hone my H.S, rockers with a two stone brake hone quite a bit.

[PaulProe]

As expected, PRW is blaming the builder - not their fault. How come I knew this was coming. Saying the pushrod was too long and hit the rocker and the spring pressure is probably too high.

• no witness marks on the pushrod or cup
• no witness marks on the body of the lifters
• spring pressure at full open is 365lbs, there spec says 375+ is OK

Can anyone comment on the travel path on the end of the valve stems. The rocker failed on the intake side (left in the picture).  In my mind, the travel path/geometry looks pretty close but I defer to the experts.

Thanks

Paul

[Stangman]

The one on the left looks fine but the one on the right unless it’s just a weird picture it looks like the rocker need to move over to the right. But to answer your question the geometry seems right.

[pbf777]

"use a brake hone on the rocker bushings to open them up about .001."


     Just a note:  Best to limit the use of a common "brake-hone" to de-glazing and just general clean-up operations; though good results are possible with exceptional technique, generally if attempting to remove any significant sum of material (and .001" is significant  ) it will prove challenging to keep the hole round and without taper or hourglassing in it's length.   

     Preferably, take the rocker arms (with the shafts  ) to a machine shop, preferably one with availability of a 'pin-hone' machine to execute the job properly and should be holding the tolerance to within tenths of thousandths of an inch; and just specify the clearance value desired.   

     I wish that these rocker clearances were always delivered "tight", that way the engine builder could have the option of setting the desired clearance, that rather than the all to often excessive sum as is often the case; so feel fortunate if yours show up out of the box tight and take advantage of the opportunity to make for something closer to ideal.   

     Scott.