Which Chevolet included this type method in the mid 1950 service manuals on the for the new 265 C.I. and 283 C.I. V8 solid lifter motors
Those where some old slow opening lobe designs, probably not good enough for todays race cams

EOIC is the best way. Even then, find where the rockers are gonna be loosest by rocking the crank back and forth with a breaker bar.

Unless someone can convince me otherwise, I’m going to say that your lash dimension should remain the same from a few degrees after the valve touches the seat until a few degrees before it lifts up. No reason the backside of that lobe shouldn’t be perfectly round.

Makes sense to me!

It is not the roundness of the heel of the cams that makes the lash change, it is usually the cam flexing

Hey, Cab, How much do you think a cam will flex with a seat pressure of, lets say 150# and open at, lets say 375#???

I have no idea
That could be measured though, if you want to find out
Years ago Dominic, Thumperdart, took the time to find out that by adjusting the exhaust valve when the intake valve just close versus adjusting it with intake valve opened past max lift and adjusting it when it started to close and before it closed all the way made a difference on the lash his motor had on the exhaust valves
Lots of choices out there, some are harder to make than others
When you look at the firing order and valve opening and closing #2 leads #1 by 90 degrees, correct. Both of those cylinders have all four lobes on the same two cam bearings, all four lobes side by side, correct
That would be the easiest one to check to see if the lash on #1 changes when the valves on #2 are opening and closing, correct
If you do check them let us now what you find please
Theory is one thing, real world is another, sometimes you have to deicide if the battle your considering is worth fighting over, correct

That’s good info and insight, Cab. I would believe it.. Begs the question, However: How does this effect how you take your readings and make your adjustments? It would seem that flex is a variable that can’t be mitigated by any specific adjustment method..... or can it?

Certainly it would be more of a factor the more spring pressure you run. For guys that run flat tappet cams, this would seem to be much less of an issue than the solid roller setups. (Stating the obvious).

OK, I was asked to get back with some test results. As I said before, I have been adjusting my valves with the other valve on that cylinder completely open. After reading and trying the suggestion posted here, I just got done checking my valves. Here is what I found. First, I checked clearance as I have been adjusting all along. Settings were all good. Then I tried the EOIC system. With my smaller cam, the adjustment did not change at all. I then checked with both valves on the seat on the compression stroke. Again, the settings remained the same. Sooo, with my cam, it really didn't matter what system is used. With a bigger, more radical cam, results may vary. Thanks for all the replies.

Good testing and feedback