I must reiterate that you should do some reading over on s b f t e c h .com.
There are a few really good pages on adjustable valve train and proper geometry.
Wear marks will show on the valve stems, you want to keep the wer marks as thin and as close to the center as absolutley possible.
Again, "springs should be good to xxx lift" as a statement, scares me!
You need to KNOW exactly what the requirement is, and then how close you are to actually meeting the specs.
Even out of the box brand new stuff needs to be confirmed. People have bad days at work, and springs look a lot alike when they are loose in abox.
Try and borrow a carb just to check yours out.
Is there ANY mechanical noise that you can hear with the engine running?
A static method to check for coil bind, is to check the clearance between the coils on both valves when the cam is at full lift. Google it, or maybe even on you tube there should be a more solid example.
When planning a cam, there is a LOT more to consider than just gross lift. Spring rates, coil thickness, installed height,shims, piston to valve clearance issues.
And, just because you may have just enough clearnace when the motor is cold, don't forget how much stuff 'grows' when the engine is warm!
A difference of".015" is a TON at normal operating temerature and 4500rpm, but to see what that measurement is physically, is like four pieces of paper stacked on top of each other.
Try to create a pass/fail check list for your engine.
Timing chain wear?
Ignition?
Firing order?
Piston to valve clearance?
Coil bind height,correct installed height?
Carburation?
Direction of engine rotation?
Balancer?
#1 on TDC, rotor pointing at #1, pointer pointing at "0" on balancer before starting?
You know the engine does run, you just need to figure out why it doesn't run like it is supposed to.
These are a few things to confirm, deny, double check, and make notes, so you can answer these questions when they come up again.
The guy that did my machine work ALMOST had me convinced, that I was breaking valvetrain parts due to bad gasoline, and had nothing to do with mechanical failure.
I was suffering coil bind. I went through two sets of roller rockers, three sets of push rods, and two cams before I was able to PROVE what was going on.
So then the guy says, coil bind, and the bad gas.....
Ha, you must really want that beer. Apprecaite the effort you're putting into your post here...
Item by item:
Noise: Yes, there is some mechanical noise when the engine is running (some of it either wasn't noticeable or wasn't there during that 3 minute stretch that the engine was running great, for what its worth), but its hard to pin down or describe. I could try to take a stethoscope to it and narrow it down...
Springs - I did research the closing/opening pressures and spring rates and, as I said, mentioned that the to CompCams and Trick Flow techs. They weren't exactly the #'s that Compcams recommended but they said it would be okay. That said, I could see that not being the case... the springs (and heads in general) were designed mostly for later 5.0s, with roller valvetrains, faster ramp rates, etc. However, I am still unclear as to how I could prove one way or another that coil bind is the issue. Is there a # for what the clearance between coils (coil to coil?) should be?
Roller/stem wear - I will check that to see how they're looking. I believe I did refer to the SBF tech article you're referring to when I actually measured out my pushrods, but I will re-read it this weekend.
'
Carb... I'll work on it, most of my buddies with carbed cars round these parts have moved out or are broke and don't have their cars now, but I'll try.
Timing chain - will try to check at first opportunity visually or via one of the othe rmethods suggested. I will say we actually did try the breaker bar idea but too much stuff was in the way.
Ignition - unfortunately I really don't know how to check this, I suppose the entire issue could be due to the MSD failing or something but there has to be an easier way to know than plugging in a new MSD. A faulty MSD would explain the hard starting, the backfire... just about everything. Do MSD's fail often? This ones about 5 years old, maybe 10k miles. Outside the MSD, I highly doubt any other ignition components are at fault. I've changed everything else and the problem didn't change with them, so I think my current parts (and probably the old ones too) were fine.
Piston to valve clearance - we put big ol' blobs of clay in the combustion chambers, fabbed one of the heads up and rotated the engine... the piston didn't even make a mark on the clay(stock 72-73 low compression engines... i don't think piston to valve clearance is an issue lol).
Firing order.. I'll check but yeah, doubt its an issue but what the hell.
Whats the best way to check for vacuum leaks? The summit guy said something about spraying carb cleaner (but also said to be careful but i forget why...). I doubt that the primary problem is a vacuum leak, but I wouldn't doubt that one might be contributing...
Carb - the sheer volume of instructions out there on how to tune Holleys is scary. Whats the quickest way to check the floats and ensure that the power valve isn't 'loose', as someone above described? Besides messing around with the choke and idle mixture more, what else can be wrong?
Current list of possibles include:
Timing chain stretch/damage
Ignition module dying
Carb being a piece of trash
Coil bind/improperly set valvetrain geometry
Coils being mismatched
And is there a guy in socal I can just pay $500 to do all of this? A lot of this is going to be hard to check without running up a $1000 summit bill and checking components until I figure out the one that failed and returning everything else, it seems *crosses fingers*
Have to work be back in a second