You've got some good advice already. 80°F is not a hot temp for a Volvo.
We routinely experience temps in the range of 90-105°F here in Oklahoma
(not much this summer so far) and normally don't have that kind of problems.
In fact I have not had vapor lock even though the coolant was boiling.
I think you probably should do several things.
1. Make sure that your heat shield is big enough or maybe even get one
custom made to be sure that it is protecting your carbs from the radiant
heat of the exhaust.
2. Check your ignition timing to be sure it is not retarded - this will
make your exhaust MUCH hotter, to the point of glowing, cracked manifolds
and pipes burnt off at the manifold joint. Err on the side of too advanced -
if you get pinking you can always retard it back a bit.
3. Check your float level. Too high will aggravate hot flooding. Also be
sure your float valves are closing properly so you don't flood.
4. Make sure your fuel lines are routed away from hot spots.
5. Make sure your line from tank to pump does not have any leaks that
make it suck air instead of fuel. These will be worse in warm weather.

BTW I HAVE had problems with hot flooding, but not with vapor lock, not
even in the Arizona desert at 125°F.
--
George Downs, Bartlesville, Oklahoma, Central US