I have a retroroller cam and roller rockers installed. The Builder told me I did not need guide plates or self-centering rockers as the reworked cast iron heads will guide the push rods and center the rockers. Yet I have several rockers that are not centering. Was he right or wrong or what? What am I missing here?

 

If you center that rocker arm, does the pushrod rub against the head casting?

 

I can't move it. Looks like that is why it's not centered. I guess I need to open up those holes and put some guideplates in.

 

what manufacturer and part number are those heads?

 

They are Chevy heads off of a 69 camaro. Had them modified with larger valves and screw in studs. Not sure why the old man didn't catch this. Live and learn I suppose. Guess I got some work to do rather than cruise.....dammit.

 

Yes it is strange the machine shop didn't catch that. Should have the guide plates. You checked the casting number on top of head to confirm original usage?

 

if OP installs the guide plates, do those pushrod holes in the head have to be opened up so that the pushrod alignment occurs at the guide plate instead of the cast slot in the head? me thinks yes? otherwise you could get binding?

 

You are corect.

 

When you pull out the stock press in studs you need to thread the boss for the screw in studs. If the threaded holes are not 100% PERFECTLY located, you will have this issue. This is an example of what happens if you try to cut corners at the machine shop.

Best practice is to drill out the obround pushrod holes larger and mill the tops of the rocker arm bosses down flat about 3/8". That way you will have some adjustability at the guideplate / valve stems for better alignment and you can lock it down when you tighten the studs at final assembly. You also need guideplate compatible hardened pushrods with this new setup. Make sure to get the screw in studs with the hex shank, not the straight ones. The ones without the hex shank have been known to crack the rocker arm bosses when tightened fully. Just do the job right.

You have no other option at this point. Pull the heads back off and go to a machine shop where they can finish the job.

 

In your first pic, the keepers and valve stem tip height does not look right either.

 

Just a thought.
Are those Intake Bolts correct? Meaning the right length? In some cases, a too long of bolt will engage with the pushrod.
For what it's worth, there is no need to install a washer under a "washer" head bolt.

 

In the first photo / post #1:

Maybe it's just the camera angle, but it looks like the valve-stem tip is shorter than its partner.
And it appears that those retainers might be a tad too small of diameter for the spring.
Plus, the inner spring on the left looks different than the right one.
And, those pushrods almost, I say, almost look like big block rods. I assume the pushrods are shorter due to roller cam / lifters.

The stud girdle maybe doing more harm than good.

 

you are right, looks to be something else going on there. I'm going to dive deeper into it. Thanks for catching that.

 

That exhaust valve is on the ramp of the cam lobe so the valve is off its seat, as it should be.

 

Yes, but it looks like the valve stem is "sinking" into the keepers....

 

The stud girdle is a head scratcher here......it is not needed until you start approaching 500lbs open spring pressure.......and I assume this is a hydraulic roller.....with a screw in stud......and those investment cast rockers are not rated for that kind of pressure.
But the pushrod hole is drilled off center by GM IMHO......a stamped steel stock rocker would never show this misalignment as it is wide at the tip/foot.....
Isky used to make a tool for this.......in fact, you can do it on the car if you are careful.......it locates off of the rocker stud holes......and has a cutter that goes in a drill......but a search comes up empty.
You may have to pull these and have them milled....then use the guideplate.
As a side note....this is why I always mockup valve train prior to putting everything together. In one shot you can get pushrod length and see if anything looks out of place......I recently had a 406ci Pontiac with Speedmaster heads that I had one guideplate that needed to be slottedit was machine incorrectly....this is a PITA....and it makes you wonder how it got that way but I made it work and everything else checked out....but is an example of how stuff that is surely supposed to work, doesn't work......your machinist should know that.....and if they told you to spec a stud girdle with no guide plates I would find a new machinist.

Jebby