The peak RPM on my 440 is steadily going lower and lower. When It was first built it would buzz to 6500 no prob. Now it it struggles to hit 5000. The combo is a .030 over 440 with a .509 cam, ported 906 heads,Eddy performer RPM with a 850DP. Ignition is a MP electronic distributor with a chrome box. timing is 37 degrees total. I use a Carter electric fuel pump that puts out 15 psi thats regulated to 7 psi. floats in the carb are dead on. I'm guessing valvesprings but what else could it be? Who makes the best valvesprings

How long since the rebuild?
Did you use new lifters?
Did you break in the new cam properly?
I hear Comp Cams are good. That's what I plan to use when I do my 318...

It was done 3 years ago. But the heads were put together over 10 years ago. I used the comp cams break in oil and run Valvoline VR1 oil.

I am kinda worried the cam is going flat....that would be bad

If in doubt about the cam, pull the intake and have a look. Better to catch it early before lots of metal goes in the engine.

On the springs, what does it have on it? The .509 has lots of duration but moderate ramps and lift so it isn't too hard on springs.

Another possibility is the ignition box. Try swapping with a known good box or even a parts store replacement. It seems QC on MOPAR ignition boxes has been a problem for a while.

I'm not sure about the spring specs. When the machine shop rebuilt the heads I gave them the cam specs and they installed the new springs. I originally thought about the ignition box, I had an orange box and changed to a chrome,no change

Theres no real valvetrain clatter that would indicate a cam going flat. It still feels like its making power at lower RPM but falls flat above 5000. It doesn't backfire or pop and idles good.

Not starving for fuel is it?

Remove a few springs and check them for load on the seat and open pressure. The mp cam doesn't need a monster spring,but there is no way I'd trust my luck with very old springs. I just went through this with a friend. I built him a SB for street/strip use 12 years ago. He calls to tell me that it's lost mph and rpms. The old springs were very tired and likely were worn out years ago.On the positive he's won enough money over the years that new springs didn't hurt the wallet much.

hi
change your fuel filter first , then check psi at carb under w o t .