I have a 67FB with a 351C 2bbl out of a 72' mustang. I'm not getting fireto all my plugs. I have replaced plugs and wires,
check that the firing order is right, made sure the dizzy is in right. It seems as if it is miss fireing on 4 of the plugs(don't remember which four). Could this be a coil problem or maybe points and condenser.

 

Kind of uncommon to get spark in some cylinder and not others unless there is a problem with your distributor. I would start by converting to a pertronix electronic ign for right around $100.
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Although I would like to do that {pertronix} cash flow is a little tight right now.

 

How do you know that not all of your plugs are firing. Did you fail to see spark from a removed wire to a grounded part of the engine (which is most any part)?

Or, do you think it is mis-firing because it is running rough. Have you checked the dwell? Is the timing not advanced enough? Is the carb balanced?

John

 

If the points are correctly set, there is no improvement with Pertronix, except convience.
Do you have an spark indicator tool? Their cheap.

Is it missing at idle or all RPM?

If it only at idle it could be fuel.Try adjusting the idle mixture is it is missing at idle, might be to lean.Also vacuum leaks.

 

There would be if one or two of the cam lobes on the distributor shaft are worn. And yes, I would get a spark test light from the parts store. They are under $10 and will tell you if your cylinders are firing without the fear of getting zapped.

Question: Are you just assuming some of the cylinders are not firing because it is missing?
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No I have used a timing light to check fire, putting the clip as close to the spark plug boot as I could. And it is running very ruff, that is why I checked fire. Is a timing light not a good way to check each one? I figured since it picked up on the #1 cyl plug it would on the other one'sas well.

 

Do you have a good engine ground?

 

That will not tell you if your plug is getting spark. Creative thinking though. If your engine is missing, it can be anything from your ignition to your electrical system to your carb. You changed your plugs and wires already. I know you said you checked the firing order already but do it again. Check the inside of your cap and the rotor. Make sure the points aren't burnt and check the dwell. If you can, check and see if your coil is getting 9.5-12 volts(correct me if I am wrong please). Maybe your alt is not charging your battery and it's draining your system. Check your grounds as fastbackford351 noted. You are just going to have to troubleshoot this by process of elimination. I know it's aggravating but that's the joy of owning a classic. Good luck and please let us know if you make progress.
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I'll have to check about the ground, are you talking from block to firewall? And of corse from bat. to block.
The alt. is putting out 14.4 volts at idle. And I guess I'll go by a plug tester to make sure of the firing of each one.