Hey all,
So I've been having this issue for quite sometime. 1976 F250 Highboy, 390 4 speed, running project
Problem (starting):
Truck has issues starting, sometimes have to crank/turnover for 15+ seconds before it catches. Sometimes I have to feather the gas pedal as well. Regular weather, no extreme cold or anything. Once it starts it idles well. If i turn it off after it's started usually starts right up with only about 2 turnovers.

Problem (power):
On a flat, when I'm shifting, in the high RPMs of 3rd and into fourth, it feels as though there is a "putter" and i have to put it to the floor to reach a good RPM. On hills (nothing big at all, mild grade) i have to put the pedal to the floor to get up the hill and drop to about 25 mph.

The local shop has rebuilt my Edelbrock carb and timed it. I've replaced the starter, plugs, wires, coil, distributor (motocraft), cap, ignition module. Still says the same...should I consider new stronger distributor? Also, I live in Colorado at 7000ft would this affect things like air/fuel ratio etc?
Any advice for fixing the slow start and power issue would really be appreciated, thanks!

 

Slow start and low power could be a fuel delivery issue. At 7,000' current spec gas may be boiling and causing vapor lock. The fuel pump may be trying to suck vapor. I had a similar problem after installing a 38 gallon tank and more restrictive 5/16" pickup. I diagnosed by rigging a fuel pressure gauge to the carb inlet. It was hooked up with a "T" and duct taped to the outside of the windshield. In hot weather and running hard on the highway, fuel pressure dropped very very low (vs 7-9 psi spec for OE pump & carb). I added a rear mounted electric fuel pump to fix it.

With a near stock engine the Mr Gasket pump was sufficient mounted on the rear frame rail.