be very careful with any MSD ignition system hooked up.. as they put out a lot of voltage above battery voltage to the positive and actually thru to the negative side of the coil.. it will burn out most electronic test gear.. i have seen it let the smoke out of 20,000 roll around turn up scopes.
inside the distributor... there should be a small braided or flexible wire that connects the breaker plate.. to the distributor housing.. this supplies the upper breaker plate with electrons... if its frayed.. you may have issues..
i would like you to examine the pivot on the breaker plate..
perhaps disconnect the vacuum advance see if your low RPM misfire goes away... or does it continue till a higher RPM.. the breaker plate pivots wear.. when the vacuum advance pulls on the upper plate .. the points gap actually changes..
is there a part number on your MSD kit.. or on the control box.. so i can look it up easier. is it a MSD 5520..
from the MSD manual..
Power Leads: These are the two heavy gauge wires (14 gauge) and are responsible for getting direct battery voltage to the Ignition.
Heavy Red: This wire connects directly to the battery positive (+) terminal or to a positive battery junction or the positive side of the starter solenoid.
Note: Never connect to the alternator. it will blow the alternator out with the amount of current surging..
Heavy Black: This wire connects to a good ground, either at the battery negative (-) terminal
or to the engine. wayne likes to ground the heavy black wire directly to a good spot on the engine..
Small Red: Connects to a switched 12 volt source, such as the ignition key or switch.
Orange: Connects to the positive (+) terminal of the coil. This is the only wire that makes electrical contact with the coil positive terminal.
Small Black: Connects to the negative (-) terminal of the coil.
This is the only wire that makes electrical contact with the coil negative terminal.
Gray: Tach output wire. Connect to the tachometer or other rpm device.
Trigger Wires: There are two circuits that can be used to trigger the Street Fire Ignition; with points its the
Points circuit (White wire) this is the wire from/to the distributor..
i realize that you have hooked this up properly.. but i am not standing there looking over your shoulder..
i would like to know.. ford coils use Push on wire connectors.. the studs are threaded .. its like a 10-32 or 12-32 machine screw nut size.. so you can use Ring terminals ..
i don't recall if this will fit your HD distributor or not. its been 25 years since i worked on an HD ford.. this is a NEW 10 buck breaker plate for ford distributors..
RockAuto Parts Catalog
might be available locally..
you might also.. want to see if you can use the cap, rotor, cap adapter.. to allow you to go to the 8mm or larger wires that use HEI style wires..
lastly.. you may want to examine your firing order.. the 7 and 8 cylinder which are the last 2 on the drivers side of the engine... follow the wires forward to the cap.. if they plug into the cap next to each other.. you will want to reroute the wires where the cross the valve cover in the spark plug wire separators.. please install them in this order.. ONLY on the drivers side.. 7, 5, 6, 8 so the 3rd spark plug wire is in first holder position followed by the first and second wire then the forth wire.. this puts the 7/8 wires far enough apart to avoid cross fire.. this happens on some fords.. and all chevys..
you may and it would probably be a good idea to print and perform this voltage drop test with a handheld digital volt meter.. only takes a few minutes..
http://i.imgur.com/WMDprhm.jpg
don't use it with the MSD connected.. but there is a way to reconnect the points type ignition to allow you to adjust the points dwell.. i am taking that the condenser is screwed down tight.. the points contacts are clean. not corroded or burned
if you had a spare distributor cap.. you could bore a hole in the side.. so you could look thru it with the engine running to see the points.. you could aim the timing light thru the hole... even though its flashing 3 times each time.. and you will have it hooked over the coil wire for this test.. its just a thought.. since its hard to monitor the points with an MSD hooked up without blowing the electronics out of the diagnostic tool.
why does it blow up diagnostic tools..
WARNING: When using a capacitive discharge ignition control,
there is high voltage present at the coil primary terminals.
Never touch the coil or connect test equipment to these terminals.
so even though the points are closed and electrons are flowing.. when the points open.. instead of 10 or 12 volts coming thru the coil primary.. you have 300 or 400 volts coming thru..
this may or may not help you ..
By the way.. you mentioned that its a 361HD... but your user name is a 240.. that was also a ford truck motor..
this is a cap and rotor kit that might fit... but you will need the adapter..
http://www.autozone.com/ignition-tu...977/8-cylinders-j-7-5l-4bl-ohv/27787_0_45590/
this is the proper cap adapter ...
http://www.autozone.com/ignition-tu...7/8-cylinders-j-7-5l-4bl-ohv/125_170550_2236/
you will probably be stuck using a 77 F250 460 set of spark plug wires.. they should be close.. but not perfect.
http://www.autozone.com/ignition-tu...nce/wireset/duralast-gold-wireset/456400_0_0/
still you need to verify the larger cap does not interfere with the intake manifold.. water pump housing.. as some models have a raised water pump mounting..