After quite a bit of Googling and forum-reading, I'm no closer to deciding which way to lash the valves... there is considerable disagreement on the subject, as usual. This is what I have read:

Obviously at TDC compression, both valves are as closed as they're going to get. It only requires turning the engine 90 degrees, eight times, and going to the next cylinder in the firing order to do both. But with really long opening/closing ramps, it's possible that a lifter could be a couple of thousandths "up".

The EO/IC also requires 90 degrees, eight times, and the use of a chart (or a good memory). The valves will absolutely be on the heel of the lobe though.

I have to lash my valves again anyway to determine if the .006"-tight when cold rule of thumb (Al heads, Fe block) is accurate, so that would be an opportunity to check if the two approaches read any differently, at least with my particular cam. Although it's 272@.050, it's a 1.00" mushroom lifter, so has a relatively fast opening and closing. From reading the cam card, the exhaust is a long way from opening at TDC (just leaving the seat at 95 ATDC) , and the intake has been closed for a while (seat = 99 BTDC). Even if that seat degrees are at .006" lift, no way are the ramps on a solid cam that long. I think.

Thoughts?

EO/IC here. No chart, no turning 90°. Just keep bumping the starter w/ a remote start button.

I use EO/IC with a bump button. For me, it allows me to not have to keep track of where i am in the rotation as i go. i can easily get one cylinder done at a time with minimal thinking!

I’ve used the @ TDC firing method, with a small cam I think it’s fine. Anything bigger or to be sure the EO/IC or the chart that has you doing about the same in 90° intervals is superior.

I’m kinda of a newb so I use the chart. I’ve done EO/IC at least once but depending on where the engine stops the lash I measured varied by a thou or two definitely WAY faster tho

This way for me too.

Putting both valves closed on compression doesn't give you the deflection in the valvetrain. I've compared the two methods on solid roller and flat tappets. In fact. I have a tight lash Racer Brown solid roller in a 470 going together now. Trick flow 270 heads on a iron 400 block. Doing EO/IC for .007 intake and .009 exhaust. Gives me about .001 or .003 lash on TDC

I just saw on excellent utube vid on this. (1) be at TDC #1 compression. (2) snug all rockers to zero lash. (3) turn crank 90 deg & adj all loose pushrods to zero lash. (4) turn crank 90 deg & again adj all loose rockers to zero lash. (5) repeat 5 more times. (6) add preload to all 16 rockers. you're done. later I will post the name of it so you can check it out your self, I was impressed. EDIT "hydraulic valve adjustment made easy-your engine guy". "Ellisons machine shop-your engine guy". check it out & see what you think. RR

Also the hot lash minus 0.006" = cold lash was very close on my stock block 440 with Trick Flow heads.

I've used both ways, if you can use a breaker bar and socket on your motor in the car then I would use the set them at top dead center on the firing stroke method as long as you know exactly were TDC is on each cylinder such as having a crank dampener with 90 degree markings so you can turn the crank to each one of them in the firing order. I'll pull the distributor cap off so I can either start at #1 or # 6 cylinders and go from their so I only have to turn the motor over two complete crank revolutions to set all eight cylinders.
If your going to use the ex. valve opening method to set the intake valves and the intake valve closing to set the exhaust valves be careful on bumping it over on the starter a little bit to much
Pulling all 8 spark plugs out using a breaker bar works well for me

Thanks everyone... but unfortunately I have much bigger problems now.

A couple of days ago, as the engine stopped I heard an interesting metallic "clinking" (sounded like something hitting the valley pan, or possibly the #2 header tube that runs very near the shock tower). It wasn't there at idle (or higher), and I couldn't find anything and it didn't come back. So I drove it to two cruise-ins (about 10 miles each, one-way) on Fri and Sat, no problems or noises, ran it up to 5200 a couple of times.

Today I fired it to warm up for lash setting and cold vs. hot check, and once again at almost-stalling engine rpm the clanking came back, louder than before! So I shut it down and decided to disassemble as necessary until I found it. I clearanced the header tube, and pulled the valve covers. No loose pushrods or broken rocker arms... ok. I started running the valves in firing order from #1, and when I got to #4 I could see that one keeper half on the exhaust valve wasn't properly seated and had popped up a little Oh poop (paraphrasing), I said, that clanking may have been the valve meeting the piston

A close look at the rest of the valvetrain showed the same problem on #5 intake. Naturally, one on each head, so if those valves are bent, both heads have to come off - in other words, the entire head R&R has to be done over again.

Before you ask, yes, I did check piston-to-valve clearance and the intake measured .114" and exhaust much larger. So I'm somewhat at a loss as to why these keepers came loose - I was careful to check all 16 when assembling the seals and springs on the bench, to make sure they were seated.

I guess it's time to order another set of 10 degree locks at a minimum. Maybe I'll get lucky and those two valves and guides will be intact and I won't have to pull the heads for repair, but I'm not holding my breath. Right now I am walking away for the night and taking a few deep breaths.

I would start with a leak down test or at least a compression test!

Thanks for the tip. I do have a leakdown tester so I'll check that too. First I want to see if the valve goes up and down smoothly and can be rotated on the seat.

I'm more concerned that the involved valves may have been stressed - you know what happens if it breaks and drops into the cylinder

Just for the heck of it if it's a automatic check the converter bolts.

Thanks, but I have a 4-speed

How far have one side of the keeper moved up ? Obviously that issue needs to be straighten up. With as much V/P clearance you have, you're probably ok. A boroscope or one that attaches to your phone would be helpful.

If the sound you hear sounds like sheetmetal, check your dustshield at the bottom of the trans, and the metal shim/gasket at the starter, if you have either these.

What he said. been doing it this way since it was taught to me over 40 years years ago. hydraulic or solid, new build or existing motor. One couldn't PAY me to do it any otherr way as I've never had a noisy valve

Heavier clink than that, and no sheetmetal dust shield, it's a Lakewood.

It's worse than I thought.
Starting a new thread over on the race and engines forum...

I've seen what happen to your motor on a engine dyno doing testing, I'm almost positive it was, is, caused by to little spring pressure for the RPM that motor is turning with that CAM

I know too little pressure can cause major issues at high rpm... but explain how it worked fine with stock-type (3/8" stem, 2.08/1.74) valves using the same set of springs, rockers, pushrods? It should be about 130 on the seat and 430 over the nose from the Comp tables. For almost 1400 miles, and NEVER going above 5200 rpm? That's a very low rpm to worry about valve float from low spring pressure.
Also, Schneider Cams (who did the regrinding) recommended 120/365 which does seem too low...

The valves in the new head are 11/32" stem, 2.14/1.81. They are probably even a bit lighter

Also, why would it be only three valves out of 16, two intakes, one exhaust?

Only God knows and maybe Murphy, not us.
I have broke more than one of those stock 7 degree single groove keepers juts like yours did, no more using them ever.

Thanks Cab. These were 10 degree locks, though.
Feel free to follow and contribute to the new thread ("Valves meet pistons") on the Racing forum, your advice is always appreciated