Exhaust manifold heat flap position if no spring

[Bruce_W]

In order for a pump to work it has to have a one way valve. So your fuel pump does have a one way valve.

Actually it has two. Heat from the engine after shut-down heats the pump and the pump-to-carb line and the fuel inside expands and even boils. When fuel in the carb bowl boils and escapes thru the metering system or the bowl vent, the float drops, opening the needle valve, and boiling fuel from the line is admitted, adding to the problem.
  You might try letting the engine idle for 30 seconds or a minute on hot days before shutting down, let the fan cool the radiator a bit, and purge the HOT air from the engine compartment.   BW

[SteveKfl]

This may be a too simple of a question... but sometimes we can overlook basics.  Do you have the proper fiber gasket spacer between the manifold and the carb to help dissipate heat transferrence?  and/or the gasket between the manifolds as well, at the riser location?  Otherwise, I would think ALL L-heads would experience the same symptom, especially those in hotter climates.  Remember the old clothes pin trick of the fifties for vapor lock?  Maybe that might dissipate heat too and costs little to try.  Have you tried it with the gas cap off or loose to see if maybe the vent is not working?  Sorry, just "guessing alternatives" out loud.  Good Luck! 

[squidtone]

No I appreciate all the comments. I will make sure of the gas cap. It's a new one from walcks and it seems to be fine but I'll check it for venting after driving it a while.
I may not get to this for a couple weeks though. An apartment full of furniture/stuff is in between my Jeep and the open streets...my daughter is moving and I'm storing stuff for a month or so.
So in the meantime I will re-plumb the fuel lines (and add the return) as well tear into the engine to check my timing gear oil jet size.
(I do stuff backwards...the engine sat on a cart for years...I shoulda done the oil jet then!)

[squidtone]

I've got an update on my hot start/flooding problem.
I made up a bypass fuel line to bleed off fuel pressure. I believe technically I've converted the "deadhead" fuel supply to a bypass supply. My Holley regulator has two outputs, so I used one output and screwed in a modified hose barb; I plugged the output and drilled in an 0.032" hole. From that, I ran a 1/4 rubber line down to a "T" I installed onto the input side of the fuel pump. This allows excess pressure to bleed off through this orifice back into the fuel inlet (which is essentially the fuel tank).
So, when running, the orifice is small enough so that I don't bleed off too much of the pressure required to keep the carburetor filled, but bleeds off pressure when the engine is shut off.
I plumbed it all up and fired up the engine. I did have to very slightly adjust my regulator to get back to 1.5 psi. RESULTS: The fuel pressure gauge now goes right to zero psi when I shut the engine off. I can confirm now too after a couple weeks of hot shutdowns that I have had no problems at all with flooding.
I've attached a picture of my set up:
Note the new hard line from the pump to a new glass fuel filter....which is installed into the input side of the regulator. The back side output of the regulator goes to a brass block which the carburetor "banjo bolt" (whatever it's called) goes through. The far side of the block has a fuel pressure gauge. Finally, the front side of the regulator is the second output where I screwed in the hose barb with orifice that is plumbed to the "T" by the fuel pump inlet. Whew. It works great.
The other lines are the vacuum lines for the wiper motor. I couldn't find old style brake/fuel line organizers, so I made up "zip tie" organizers.

So I think my original question about the exhaust flap was a red herring, but even so I hope to fix that up with a new bimetal spring and get it working.

[SteveKfl]

Very professional looking, and it works too!.  Nice job.

[BillT]

Just for kicks try clipping a couple of clothes pins on the fuel line at the carb inlet. They are suppose to act as a heat sink. I have seen it done but never knew if it actually worked.

[ndnchf]

I just resurrected this exhaust manifold.  The flapper and exhaust pipe nuts were frozen.  But a few days soaking with penetrating oil, bead blasting and gentle taps on the shaft got it freed up and the nuts off.  I made a new key to align the lever on the shaft from a piece of hacksaw blade. It worked perfectly. Its all cleaned up and coated with Eastwood's cast iron high temp coating.