[TR] Need help with '79 Triumph Spitfire starting problem

[BJ8 Healeys]

Hi, Triumph fans -
 
I've been helping my neighbor get his '79 Spitfire in shape after he bought
it sight unseen from eBay.  It starts easily now, idles and drives well.
The only problem I haven't been able to solve is that once the engine is
warmed up to operating temperature and then shut down for about 15 minutes,
it will crank but not start.  If started within 5 or 10 minutes of shutdown
it does fine.
 
I've had the Stromberg carb off twice and made sure the water choke is
operating and is adjusted properly according to the Haynes manual.  If the
bonnet is left open, the starting problem doesn't happen. This sounds like a
vapor lock problem, but stuffing extra insulation between the carb float
bowl and the heat shield and insulating the fuel line behind the engine
doesn't fix it.  If the bonnet is left down, the car won't start after 15
minutes.
 
Anyone run into this before and have some clues?
 
Another question:  this car has two charcoal absorption canisters next to
each other on the passenger's side of the engine bay next to the radiator.
The front one is connected to the rear one at the bottom with a large rubber
hose, but none of the three tubes on top of the front canister have any
hoses connected to them.  Is this correct?  The Haynes manual shows only one
canister, and it's shown next to what appears to be the coolant recovery
bottle.  On this car, the recovery bottle is by itself on the driver's side
of the radiator.
 
Thanks in advance!
Steve Byers
Havelock, NC  USA