If the lash cap will spin freely on some of the valves and not on others means the top of the valves are either different sizes or worn, mushroomed, correct?
If they are mushroomed take a good flat fine mill file or a good quality honing stone and get rid of the mushroom so all the lash caps fit freely on all the valves
I use lash caps to prevent damage to the valve tips, not to correct the geometry of the rocker arms to valve tip contact patterns
If the rocker arm contact tip is not contacting the center of the valve tip and sweeping across the tip properly you need a better fitting set of rocker arms, correct
Years ago I bought a bunch of W2 steel and aluminum stands to be able to mill the rocker arm stands off of BB heads and use the W2 stands to correct the height and location of the single shaft rocker arm available back then.
I ended up hearing about Rocker Arm Specials (before using the W2 stands) who will correct the rocker arm location and tip contact problems with bushings and relocating the adjuster positions and relocating the rocker arm tip contact location on the original ductile iron rocker arms we use to use.
Later on I started buying new aluminum roller rocker arms from Crane and Harland Sharp, I was thrilled that the Harland Sharps didn't need fixing on the their roller tip contact patterns to the stock valves on the stock iron heads like the other brand after market rocker arms did
Mopar use to hold drag racing seminars back before they went bankrupt in 1980, they recommended a rocker arm contact pattern to the valves on all of their Mopar V8 motors of starting on the inner third of the valve tip when the valve was closed and having the rocker arm tip slide across the center of the valve stem to the outer third of the valve tip, basically around .100 wide, before trying to correct it
I continue to use that as my guide on rocker arm tip to valve stem geometry
I have one of my drag race motors with a set of Jesel paired shaft rocker arm set up on a set of Indy 440-1 heads
My next high effort motor has a set of B1-MC heads with the original single shaft 1.7 ratio rocker arm set up, that set up will be discarded in favor of either a T&D paired shaft ductile iron rocker arm with 1.7 ratio set up or the same set up from Jesel.
Those kits are adjustable on the stand heights to get the best contact pattern on the valve tips to the valve stems
They are not cheap though
Cab,
I'm not trying to marginalize your accomplishments or experiences, and I don't want, or have the time, to get into a cat fight over this subject. But, 1980? We have full bodied bracket cars these days running faster than ProStock cars did in 1980. Almost 20 years after that, in 1999, Chrysler Race Engineering MANDATED that their NASCAR teams use the valvetrain geometry I use today. It's not a new concept. If everything today was done like 1980, we would still have 1980 results. If you are holding true to 1980's technology, then you can't use -1 heads, or B1MC heads for a build, because I don't believe they existed in 1980. If I'm wrong about that, I stand corrected, because a historian I'm not. I highly doubt Jesel or T&D had paired rocker systems at that time for heads that likely didn't exist.
If anyone one understands the concept of geometry from a true mathematical perspective, they know that a centered pattern has nothing to do with the mechanical functions of the valvetrain. After all, the only purpose of a rocker arm is to transfer the cam lobe information to open the valve at a specified ratio. It, by nature, is an inefficient design, but not having the geometry correct makes it that much more inefficient, as well as unstable.
Another point, if the lash caps are protecting the valve tips from damage, they should not be mushrooming or wearing. The fact is, a lash cap, especially with a very wide sweep, will ever so slightly rock back and forth across the valve tip and cause that erosion or mushrooming to occur. It would have to be a press fit for that to not happen. In instances where a lash cap is mandatory, ie small stem diameters or titanium valves w/o hard tips, having a tight, narrow sweep helps the valves live longer from the minimized rocking. This is also an instance where having the pattern perfectly centered is critical. Without a cap, it has no rocking and centering is not as important.
From an engineering perspective, none of the off the shelf roller rockers have proper design geometry, and certainly can not be simply bolted on the head and go. Harlan Sharp rockers are actually one of the most egregious examples, and I avoid them if possible. Any motor worth spending money on good parts, is worth an equally good custom rocker to correct the compromises in design of the off the shelf stuff.
The paired rocker systems you mentioned are indeed expensive, but the expense doesn't stop there. They have to be pushrod oiled, or spray bar oiled, which is going to involve additional parts and machining. That's why I focus on the single shaft system, to keep the costs in check for guys who don't want or need to go through the extra effort. Which begs the question, if it's ok to buy a paired system and ADJUST it, why is it so far fetched to adjust a single shaft system? I once had a guy working on a small block street motor tell me "It doesn't have to have geometry as good as a Jesel", and my answer was "Why not?". If you can get geometry as good as a Jesel with a budget rocker, seriously, why wouldn't you?
Cab, I'm just trying to help people not have valvetrain issues and failures. If the way you build your stuff works for you, I wish you well. But, if someone doesn't think my solution is viable, I'm all ears. I don't know everything, but I know logic when I see it, and I haven't heard a logical argument yet on why my valvetrain solution is wrong. But, technology changes. Maybe I'll find something better one day. If I do, you can bet I'll be all over it.
