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From: Las Vegas - Just stop perpetuating myths please.
Yea Joe there can be several reasons for the mis-alignment. Even down to the lifter bores themselves. When I use guide plates I used an ancient method taking an old junk p-rod and while holding the guide plate in a vise hammer the p-rod in enough to get a smooth gliding p-rod action when installed. Doesn't take to long but I imagine with 1.6 rocker arms each guide plate needs it.
For 1.6 rockers w/head slots vendors sell whats called a Lewis - which is a drill guide - tool but that would be for stock chevy heads - may not be correct for aftermarket heads so grinding is the only option other than guide plates.
Some sharp eyes out here! The builder used poly locks instead of the lock nuts that came with the rockers. Now that I think about it, I think he mentioned the lock nuts were 'tight' in the rockers and these were easier to install / adjust and all around a better fastener. Yes that rocker stud was replaced with an ARP stud. In this motor's short life, I found that this lifter came loose and smacked around enough to damage the stud. I replaced the stud reinstalled the rocker, and that's when I discovered how crooked it really was. As many have pointed out, this seems to be a kinda common issue with aftermarket heads.
I picked up a pair of offset full roller rockers to see if they would correct the issue. They seem to fit quite nicely. Below is a picture of the Scorpion SCP1010L-1 with .150 left offset. I just put it on finger tight to check alignment and haven't preloaded it. Obviously these rockers are built for a purpose, and maybe not necessarily this purpose, but I have a hard time understanding how this "fix" would be any 'less correct' than pulling the head, grinding the hole and installing plates. This was certainly easier! Getting a valve cover to fit over it may present an issue though.
Not very happy
These scorpion offset rockers seem to correct the issue.
To move the focus back to the A/F ratio... I just don't understand how that much air can be getting into the exhaust. Seems that would be a substantial leak that I would hear. I might pull the headers next and inspect the gaskets, but the exhaust is all new from headers to exhaust tips.
To re-dig up one of my earlier posts, although the A/F was showing very lean, I believe it was actually rich. As mentioned, while idling, the idle improved and RPM's raised when I created a vacuum leak. My understanding is if the mix was correctly set, the added air from the leak would lean the mix and cause it to stumble, not improve. Once I install the offset rockers and figure out how to get a valve cover to fit, I'll set the mixture screws based off of a vacuum gauge, verify timing and see if there is improvement now that my throttle is actually giving me WOT.
The head needs to come off and be machines for push rod guide plates while replacing that valve because it's stem tip has been mushroomed from the rocker arm making an off-center contact.
Maybe its just the camera angle, but the valvespring retainer looks like its leaning towards the right. Which is the direction the old rocker arm ended up at. Bent valve maybe? And whats the indentation at the bottom of the spring? Must be the camera angle again. Looks like the spring is ready to snap.
Just my opinon but, I think you are wasting money on off-set rockers. You need to get to root of the problem instead of band-aid fixes.
The offset rockers, although very nice, will be going back since they don't fit in the valve cover. I contacted the manufacturer of the heads to see if they'll do anything. They've been friendly so far and requested a picture of the misaligned rocker. Granted the builder should have caught this while building the motor, but I shouldn't have to machine brand new heads to get things to work either. More to come,... hopefully something good.
The pushrod holes are hard to see in any of the pictures but they are probably just a simple oversize round hole as obround slots are pretty challenging to manufacture for the aftermarket. Obround is used by GM and it could be possible here but my bet is they are oversized round holes that require either "guided tip" rockers or conventional guideplates to keep the rocker arm lined up with the valve stem. Pushrod length needs to be looked at too. OP may have bent the valves if the rocker was riding on the retainer.
Certainly not an over sized hole, and therefor no guide plates should be needed. There is only one valve per head that this is happening on and its the same push rod hole/valve in both heads. Seems unlikely that pushrod length only affects 2 of 16 valves. Although anything is possible, I think this is an issue with the head. I know that others have used this head in builds, so would be interested to hear from them if they noticed any issues in this area. Pushrod guide is machined in head
Thank you for the pix. Those are definatley obround and they look to be snug enough match to the pushrod. If a rocker does not line up with the valve stem on that cylinder especially on both heads, it seems to be a manufacturing error. That sux!
Try removing the stud and laying a straight edge across the tip of the pushrod and the centerline of the valve stem. The rocker arm stud hole could be drilled in the wrong place or the pushrod hole could be in the wrong place causing misalignment. They all 3 need to be 100% in alignment.
Before you round up a posie and a linching rope:
I think what I would do, just out of curiosity is, swap the two rocker arm studs. The one in question with the one next to it. Torque em down, assemble rockers, set lash. If the neighbor rocker NOW leans, that would determine you have a bent rocker stud. Or is it the rocker stud "pad machining" or lack there of, that is to blame?
Update: In two of the photos, it looks like the rocker stud is leaning towards the right. Might be the camera angle. That would explain the rocker arm off center.
Last edited by HeadsU.P.; Oct 19, 2017 at 12:49 PM.
