A few tid bits.....

Water temp will be in the 160's for all the testing.
Weather is supposed to be pretty nice this weekend, so air temps would be mid-60's/70's.
The dyno exhaust isn't really "open".
There are 5" pipes coming off the collectors going through the wall, where they attach to tractor trailer mufflers.
Testing will be done at a 300rpm/sec rate.

Provided everything is still going smoothly at the end of the session, we'll take the "best" carb/spacer combo and make a cold water "bonzai" pull to try for "the big number"....... But we won't use that run for "scoring"
How low I can get the water temp will depend on how many runs we have made up to that point, and what the temp of the water in the storage tank has gotten up to......... But I'd expect to be able to get it down into the 110-120deg range.

The cooler temp is usually worth something...... But not always.
I think it would be on this motor though.