Technical new engine no power

Fellas,
I have a brand new 383 that a friend of mine has me looking at. when you mash the gas it falls flat on it's face, only in drive. It doesn't matter if your sitting still or driving down the road. This thing has a decent cam in it, roller rockers, aluminum heads, the works! However, no power at wide open throttle. If you go about mid throttle down the road you'll hit your head on the glass ( it has power).
Also, sometimes it diesels when you turn it off.
Lastly, it drops 200 RPMs when you put it in drive.
This is what I have done and checked:
Fuel Pressure: 5.5 psi
timing: 34 degrees at 3500 RPM verified that it wasn't 180 out.
no vacuum leaks
Changed the springs in the 750 Edelbrock carburetor (pink 14 PSI of vacuum)
Found 2 bad plug wires that melted against the header replaced and verified proper placement in accordance with timing sequence
spark plugs are new
vacuum hoses are new

Any thoughts?
Thanks,
Joe

 

cam breakin ?

 

easiest and quickest go to a chassis dyno.... sounds like a carb tuning issue, hard way is to learn how to adjust the mixture, the owner manual for that carb is online

 

Vacuum is inches not
psi. Is that fuel pressure at idle or full throttle?

 

200 rpm drop isn't out of the norm for a stock converter. However a healthy cam needs a higher stall and the drop won't be as drastic and when you punch the throttle it lets RPM develop and off you go.

Most likely the secondary end of the carb is out of Wack. You'll need to get into edelbrock's on line tuning manual. Pretty simple to walk thru and get things working properly.

 

Valves adjusted correctly???

 

If the timing is right, the valves are adjusted properly and it has compression and good spark, when you mash the loud pedal if it falls on its face you can bet the farm that it's not getting the fuel needed to respond to the drop in vacuum signal. In other words, it's wanting more fuel on the hit AKA a bigger pump shot. Jetting for performance is another issue albeit related.

 

I agree with checking the number on the power valve. I had the same issues with a "camed" 350 falling on it's face. I put the same engine in a heavier car and had to change the power valve again to get the off idle performance I expected.

 

You say it falls on it's face, does it recover? or does it die at that point? If it stumbles (falls on face) then recovers look at acc. pump, pump nozzle, duration of of fuel shot and stuff like that. if it stumbled and will not recover with foot still in it, check stuff like high speed fuel delivery