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.