Dan, either we are miscommunicating or there is confusion...
At full throttle you cut in an extra X% of fuel flow, beyond 'max
rich'... It is for cooling the exhaust valves at take-off power...
Pull the throttle back, even a small amount, from full forward and you
lose that extra X% of cooling... It is the same for carburetor and
injected engines...
The RPM at which you can run full throttle continuously is in the
POH... Reduce power in climb by reducing the prop to that RPM and leave
the throttle full forward and your engine will be a happy camper with
cool valves... My API / CFI buddy still hasn't figured it out...

On my Super Viking Take-Off RPM was limited to 5 minutes... But you can
pull the RPM back to Max-Continuous power, still at full throttle, and
run it all day and have the benefits of the valve cooling - hard on the
fuel supply though... It is a separate metering circuit on the
injector body for full throttle cooling... Pull the throttle back as
little as a quarter inch and the valve cooling metering circuit shuts
off... Leave the throttle retarded slightly in a long hot climb and you
will likely have valve damage...

Same thing applies to fixed pitch propellprs... Leave the throttle
firewalled in climb for the cooling - assuming the POH allows it... As
soon as you pull the throttle you lose the cooling... Now, be aware
that as you climb at full throttle you are losing manifold pressure
with each thousand feet gained, which is automatically reducing the
engines output power, reducing the strain, and improving the cooling by
allowing the mixture to go even richer than it was a thousand feet
lower... Airplanes, at lower altitudes, are best climbed at full
throttle... Funny how those dumb engineers at the tractor engine
factory figured that out all on their own without any help from us god
like pilots...

cheers .../ denny