Alright, now we're getting somewhere! The lifters clear, the cam is degreed... everything should go rather quickly now!
Wrong,
wrong, WRONG. :naughty:
This would commence what may be the most epic valvetrain battle since Henry Ford deemed overhead valves a fad. It consumed the next several months of my life--I was already working on it when Stretch and I made our semi-annual visit to 68R/T in late April, and was still solving the same issue well after the second one in late September. In fact, I'm
still not f__kin' done with this battle, although for all intents and purposes it's at least sorted out.
Remember this nonsense?
As it would happen, this offset would be my nemesis for several months--something I'm on which I'm doing finishing work on the final corrections as I type this. If you've got the right bits, this is a
desirable arrangement. I do
not have the right bits.
What this represents is the original '70s Pro Stock solution for the LA engine's 59° tappet angle. That angle was a carry-over from the polyshperic A engine, where it was actually a nearly-ideal compromise (a look at poly valvetrain and you'll see why). Long prior to the introduction of over-the-counter "R" blocks with ready-machined 48° lifter bores, racers would take a '70s-era race block (the "X" block) and re-machine the lifter bores way oversize. They could correct the lifter angle via the machining itself and using straight lifter bushings, or by using angled-bore lifter bushings. It was a brilliant solution for the high-RPM demands of big ovals and Pro Stock racing,
and it used standard W2 rocker arms along with nearly-ridiculous valve lenghts (for an LA engine).
Although I knew these were oddball race heads, it's very important for me to point out:
At this point in the project (first quarter of 2018), I was totally unaware of much of the preceding information regarding valvetrain angles, and completely ignorant as to how might actually apply to what was I was doing. :doh:
"So what does all this mean, Jass? What's all your fussin' aboot?" Glad you axed. Since I do not have a 48° block, some funny things happen with the valvetrain.
The first major failing--and this is the biggie--is that with standard on-center rocker shafts and stands, the pushrods want to occupy the same space as the intake faces of the cylinder heads. I initially tried to grind my way out of that situation:
I realized very quickly that it wasn't going to work, since I'd have been left with virtually no gasket surface at 8 points on each valve cover:
In addition, the already "less than optimal" LA pushrod angles were now approaching "downright ludicrous" territory:
Up until this point, I'd been using "standard" W2 rocker-shaft stands, meaning "expensive custom ones built to Chrysler dimensions" but they clearly weren't going to work on these heads. So I reached into my W2 bag of tricks and pulled out a set of ancient Harland Sharp "reversible" stands that came with one of my sets of Harland Sharp rockers.
H.S. v. factory-spec, Sharp in front and resting on its
thin mounting side:
Reversed, with the H.S. now at the rear, resting on its
thick mounting side:
:hmmm:
Well, that gave me a little wiggle room, plus a good basis for studying the effect of varying shaft heights on pushrod angle and roller-to-valve-tip contact. Wiggle I would, and study I did--and I ran into an even more perplexing issue:
I realized I had no repeatability. As in, from one check to the next nothing measured out the same, be it pushrod clearance, roller contact on the valve, etc. In an effort to be more scientific about things, I marked one of each set of stands
and their position on the lone shaft I marked (both as the one to use and its orientation), chose only one intake and one exhaust rocker, and left every bolt in the same position. I eliminated every possible variance that would mess up repeatable results...
and I still couldn't get them.
Clearly I'd been in the garage too long, and inhaled too many chemicals. I was completely flummoxed. I could remove an assembled shaft and immediately reinstall it, and I'd get different results. The dial indicators, feeler gauges, and digital calipers all backed me up on this, even though it was evident to the naked eye something was changing--but I didn't trust my eyes at that point.
This went on for a couple of nights... and then I discovered this:
Look again if it didn't jump out at you. That, my friends, is a hardened, extra-thick W2-specific rocker shaft--and it's
fucking bent. While it was still bolted exactly as shown to the #1 and #2 pedestals on the head, I took the following series of photos.
Bolt hole alignment at Pedestal #3:
...at Pedestal #4:
...and at Pedestal #5:
I don't even know how someone could bend a rocker shaft like that, but as I found out someone managed to bend both rocker shafts in the pair identically. As evidenced by the photos, they're bent in two planes, so to speak. If I was forced to wager, I'd bet someone pulled an engine/transmission combo out by bolting the lifting chain to the center bolt holes of the rocker shafts, with only the outer stands or hold-downs being fastened. Even at that, I'd guess they forgot a couple of motor-mount bolts and lifted the whole front of the car first. These are beefy shafts, yet they not only banana away from the head, but the bolt holes aren't even in straight line anymore either. One doesn't think of steel as something squirmy, but I assure you it is when you're trying to bolt it somewhere it'd rather not be. As soon as I swapped out shafts, I had
perfect repeatability--even between different rocker arms. The intake rockers in particular (being as wide as they are) were suddenly much easier to slide onto the shafts, too.
The irony was not lost on me that I discovered the bent shafts on April 1st.
Looks great!
