Don Terrill’s Speed-Talk

Light side has a larger intake valve relief

Why is this important?

gouges in them from improper valvetrain geometry

The roller ran off the stem tip? That's going to happen again.

1.6 intake rockers, stock exhausts

Your air temperature is 180 degrees?
If the car starts and idles with no choke, the primary is too rich.

Anti-reversion insert at the port exit

The DCR fades away as RPM increases, and is gone before the torque peak.
In your operating RPM range, you have 14:1.

Remember, back when Eisenhower was President, that we all had to get used to metric because it would become universal very quickly?
Still waiting.

35 mph is about 15 hp

The big advantages: you get to tell people about it, or drive with the hood off.

A possible bottle-neck: the three Carter YH work well, but the engine bay required the manifold to be of the notorious "swan neck" design, with sharp internal bends.
A Bel Air with better manifolds might pick it up nicely.

An error resulting in a small power loss may be acceptable.
How about an error that causes every tappet to make edge contact with its lobe? 100 miles until rebuild.

Rude joke:
The time in seconds it takes for oil pressure in a cold engine to reach that last bearing is a function of the 1st number of a multi-grade (the "10" in 10W30).
Yes, that means that 20W50 takes twice as long.

In addition to the obvious engine-wrecking errors there are some that have no symptoms at all (lifter contact slightly lateral to lobe). Some just make the engine run badly (lifter bore is correctly aligned but advanced or retarded from cam journal CL, including same offset on both banks - making 1-...

More plenum volume

Maybe an error that eats cams or loses oil pressure resulting in no horsepower.

This^^^^^^