back fires and missing

Check the fuel pressure , Carb's accelerator pump/power valve and also the ignition timing-valves could be hanging up-Check engine compression

what is the tool called that i use to check the air compresson in piston chamber that screws in tho the spark plug

how do i check the ignition timing
could i have a back jet in my carb? if i switch to a carb i know works fine do you think that could fix the problem
thank for you help so far

You'll be needing a compression gauge and inductive timing lite-to check engine compression and ignition timing

well i have a bad piston ring on my 7th piston or my valve bc it is only at 55 and the others are at 120 or 115 so i am looseing compression on the 7th piston it is on time it has to do with the compression