No fire out of coil ! ,changed coil, new battery , battery line seems to give off weak spark.still no spark out of coil 73 vette with points distributer

Possible ignition starter switch problem.

I guess you could have the ignition analyzed on an oscilloscope. Maybe a tech could see something then.
I always heard the only gap was the spark plug gap-the rotor has no gap-are you sure you got the correct rotor? And does it touch the top distributor cap coil wire tower?

Let us know. It is a mystery worthy of a solution.

It could be the spark plug wire, or the coil. 2004 model you should have coil over plug (C.O.P) setup. Also check for any signs for arcing around the spark plug boot area and around the coil. Any white or gray lines on the boot area or coil is an indication of arcing. If arcing is happening, the current will take a short cut to ground instead of jumping the gap at your spark plug, thus giving you a "no fire" situation. I also ways recommend replacing spark plugs in a set along with new wires. I don't recommend just changing one.

Check fuel pressure with gauge. The filter could be dirty or weak pump. Then check injectors. That can be done by unplugging one at a time and holding the brake in a safe direction, and applying the gas and seeing if there is a greater change on one injector versing another; however, makes sure that all of your spark plugs are doing their job, including your coils and module. The spark can be tested using a spark tester that has a screw type adjuster that goes from 10k to maybe 45k. You keep twisting it out until you get no spark, then adjust it back in until you get a blue fire. At this point check all of the spark plug wires. They should be able to make the same spark. If not, check that line of fire wire, plug, and coil,etc. Good luck.

A yellow spark is usually a sign of a weak coil, change that, it should cure the problem, if not, then further testing is needed.

most likely the ign switch is ok if you are getting spark. so you have a hot spark at coil and weak fire at plugs? if you have a test light check the positive side of coil for power when turning key on and cranking. if it is dropping power on positive side then ign switch could be bad. can "hotwire" coil by jumping a wire to positive side of coil to pos of battery this will eliminate ign switch.

Look on E-bay for an electronic CD unit that fires from the original points, but generates about 400 volts to fire the standard coil. My guess is that there is no all-electronic ignition system available even as a racing option. Ford used this engine in the Pinto line of cars from`'71 to `73, and all of them used points and condenser distributors. The points and condenser units work fine if in good order and the point gap set at .025". Hope this gives you an assist!

Have a look at the coil and its supply lead, standard it has a 9v coil and a resistor wire in the harness, this gives trouble ar resistor wire is odd and will not solder or weld and its expansion when hot loosens crimps! If you put 12 volts into a 9v coil it overwhelms (magneticly) the windings and gives a poor spark, also burns the points.

check the fuel filter for possible blockages.

the fuel system has some blockages.

weak spark is no fuel issue but sign of distributor problems. seen age you still have contact points and conventional distributor cap.
Check contacts points and contact gap, feeler gauge will be enough at maximum opening when turned around. Incorrect issue is no weal spark issue either. Cracks in the cap are or worn points or dirty lead. Then the ignition coil should be good still. der-ust, clean up all contacts/terminals. Clean grease and other debris as well. If points or cap no good, replace points may be cleaned a bit carefully with sanding paper (Did that only on 1000 imported japanese cars from mayor port as a student to drive them to a parking lot.)

Timing can be set by a stoboscopic light for proper pre-ignition
you need one of those dwell angle strob light instruments.

Whole other list possible while it will not run. Battery ok?
Vacuum to distributor ok. Distributor weights not stuck?
Start to clean all and check from A to Z basic stuff. Can't be anything serious. Serious when you have grey emulsion in stead of oil.