1978 Town Car running ROUGH

[PerkDowd]

Hello to all...my first post on this site.
I have owned this 1978 Town Car for approximately 5 years, it has 46,000 original miles, two tone silver in nice shape.
400 cid engine.

My problem is it runs as though only firing on 6 cylinders.

New cap/rotor, new electronic pick up in distributor, new plugs & wires, new coil, and I thought a new ignition module "brain" box.

Plug wires NEVER seem to "click" on correctly, so I'm always suspecting that as a problem, but I would think some arc would occur anyway..
Coil has been replaced twice now, probably due to aftermarket quality.
Pick up in distributor replaced twice now due to poor quality I think.

I am quite frustrated....could there be a more serious problem in the head or piston/rings for the cylinder not firing?

Can I bypass the entire distributor pick up and brain by installing an MSD ignition?
Anyone else have problems with these cars not running smoothly?

Any input would be appreciated.
Many thanks!
Perk in Plymouth, MI

 

[Markviiiedrea]

you can pick up an in-line spark plug tester to see if the spark is actually getting to the cylinder. There cheap and should be an easy test on that motor.


Looks like this...

 

[astralis]

Photos, please. And an update.

 

[Stangman]

A '78 with only 46k on it... ancient non roller motor, probably sat a lot in it's life. I would bet maybe it has an issue w/ cam lobes being wore down from firing it up after sitting for a while, cam spins dry for a few. Possible bent pushrod, or loose rocker arms... have you checked all those items?

my '77 Mustang had like 60k on it, and and since it was barely used, it would be dry started when it was used, and over time the cam lobes started grinding off.