Down on Power (450SEL)
 

Have a '74 450 SEL w/ 256000 miles that I got 6 months ago.
Did a compression check (wished I'd saved the numbers, but they were all close and good nos.), checked valve lash which was good. Car runs very good- it just is sluggish when going up a hill.
Doesn't have enough pep when accelerating from a light.
I know it could be many things. I was told by the previous owner that he changed the fuel filter (but maybe I should check?)
Is there a way to measure backpressure resistance thru the mufflers (there are no catalytic converters). Could the fuel injectors be dirty and not delivering enough spray? Weak Coil?
Car starts easily. Timing seems to be good. Sometimes when accelerating there is a light "popping"- not knocking or pinging.
Anyway, just thought you all could give me some thoughts and things to check. Don't need a race car. Just want a little improvement.

I know there's alot of possibilities. Anyone want to take some educated guesses?

Okay, I'll take a stab at it.
Popping on acceleration would make me look at two things:
1. Lean fuel mixture,
2. Ignition ( plugs, wires, cap, rotor ).
I doubt that you would have a restricted exhaust problem, since you don't have catalytic converters.
Just to satisfy your couriosity, you could have somebody stab the gaspedal, while you place your hand near the tailpipe & observe the volume of exhaust coming out. ;)

P.S. You say " timing seems okay ".
Check it, maybe somebody retarded it too much.