Found some things out yesterday with my hard start when my 69 Super Bee 383 has sat for 15-20 minutes after running for awhile. With the Edelbrock (Brand new out of the box) I have to put the pedal to the floor and grind to get it the car to start. I rechecked the fuel pressure and saw 6psi. I hooked up a regulator and adjusted to 4.5 psi. Same result. No start Hot. I went ahead and checked the motor compression, just because I hadn't in a long time, and that was good in all cylinders. At that point I cried UNCLE and put my Holley back on paying close attention to starting hot and it does crank over a few times but starts without planting your foot and grinding away. This brings me to My next theory, Heat riser valve stuck partially shut. The Eddy bowls are hung on the side of the carb, the Holley front to back more away from the crossover of the intake. My heatriser valve assy appears to be gone except were the flapper arm rod would be sticking out of the exhaust manifold , thats still in place and stuck, can't move it. Sounds like it could be time to pull that loose and make sure. The exhaust has no crossover as well so I may be able just to check the amount of exhaust I get but the valve may well not be shut all the way cause when hot I don't notice any issues with how the car runs once it gets going.