1971 Ford Mustang Mach1 351 Cleveland
Good afternoon everyone.
1971 Ford Mustang Mach 1 Cleveland VIN M:
Checked Carb for fuel flow - Fuel Flow Good
TDC CYL 1 to Distributor Rotor Orientation - Good (Testing for good distributor to cam engagement)
Tested Coil - Failed - Replaced
Tested Condenser - Good
Points - Good
Points Gap - .017
Distributor Cap - New
Rotor - New
Spark Plug Wires - New
Spark Plugs - New
Checked Coil Grounds and Condenser Grounds - Good
Am I missing anything?
I noticed with my timing light on CYL 1 I would get an intermittent flash (pulse) to CYL 1 every so few full entire engine revolutions.
I have a suspicion that the failed coil fouled the new plugs (installed by customer's previous mechanic), and that now with a new, working coil, the plugs are still fouled, but can anyone answer whether or not a fouled plug, in not generating a spark-arc, would also kill the pulse from the Coil/Rotor/Points/Distributor?
Thanks everyone for your input and suggestions.
Check primary side voltage and coil wiring polarity (Red with Green on + side). 71 does not have a ballast resistor. The resistance is built into the primary circuit so you will see closer to 9 Volts static there. Finding good points these days is tough. Be sure the points are not grounding electrically even though they are moving. That will kill a coil while you are trying to diagnose it…
I know exactly what you are saying about the points. Nobody sells a decent set of points, or even the condenser. I flat out refuse to replace points anymore. It's either getting a pertronix unit, or a different distributor.
Put an ordinary 12V test light on coil negative and crank the engine. It should flash brightly each time the points open.
It should not kill the pulse, the kV will be very low though. You could put a new plug on the end of the wire and ground the plug case, to watch the spark. I would do it with the coil wire for best results of coil testing. Intermittent spark could easily be the points not able to work properly due to worn bushing in the distributor. I agree, dwell is the thing to look at for the quickest test…
Hello Jordan, Is the rotor similar to the old one? I've seen many boxed wrong in recent years. Next, make sure the short-woven ground lead was installed when the points were replaced, I have seen them missing or broken before. With the vehicle out of gear, park brake set and wheels blocked, perform the following: A Simple test: run a positive jumper wire to the coil positive. Then pull the…
This capture is from a 91 GM truck 5.7, crank no start, with fuel fouled plugs due to corrosion in the CTS connector. The blue channel is the TPS. The red channel is the MAP voltage cranking. The green channel is the coil wire secondary showing the fuel fouled plugs. The black channel is the coil primary winding amp draw.
I agree about testing dwell. If you do not have a dwell meter then disconnect the points lead and test the resistance thru the closed points to ground. Should be damn close to zero! If not clean the points, I used a new business card and brake kleen. Try again. My bet is NEW points, as in Never Ever Worked!
According to my 1974 Motor paper manual; correct point gap should be.021 for 1971 351C and dwell should be 24-29 degrees. Also in 71 Ford used an external resistance wire or a ballast resistor, make sure that they are intact. if not my recommendation is to install a ballast resistor or internal resistor coil. as far as points go, Napa Echlin is about the only set of points I've found left to be…
Have you tested cranking vacuum? If low, have you verified timing chain slop. More than 8° play will lower vacuum. If you can't suck it in… Have you done a relative compression test?
Paul, these things have intake port the size of porthole. Also if the cylinder head has a 4 with a cast dot in the upper corner, the compression chamber is huge! As a result poor combustion. Agreed the timing chain should be check as they are notorious for stretching. For an M code, advanced the cam timing 4 degree. with a new gear set. It will compensate for the low end loss of torque.
As nearly every one else has suggested, swap to a electronic ignition there are many kits out there. Unless this thing is a competition judged car, no one cares. Ditch the single point syste. I build and race Cleveland’s. still have one in my 66 Mustang gasser. Mallory electronic ignition.
The pulse will be there regardless of plug condition. Modern branded points are crap. Get yourself a pertronix kit,
Jordan Check for wear in distributor shaft bushing (changes point gap/dwell). Also make sure someone didn't make the mistake set up firing order for the other V8, this is the wrong firing order … and the correct is … with CCW rotation. I've also seen a “sharp” distributor gear “push” the rotor into the distributor cap and have seen the wrong height on the distributor…
With a test light , on the negative side of the coil while cranking, you should have a steady blinking test light. If not, check the primary wire from the points to the coil. Especially where it contacts the distributor housing. Dan
Yeah! You and I have provided the simplest and most concise test to verify that the primary ignition system is working.
Jordan, I'm an old guy who's lived, breathed, built, and raced old Fords all my life. I still have my 1963 Ford Custom 300 with the 406 cid tri-power, 4-speed, and factory 4.10:1 axle gears that I bought brand-new and it's ready to race :0) To begin, check B+ on the coil for a steady 12 volts while cranking. If you're not getting 12 volts at coil B+ when cranking, check the firewall connector…
I have points experience from way back. Points quality is critical. I found Standard Blue Streak points to work the best. The ones in the red box are terrible. Won't last 100 miles. I can only imagine what's out there now. A quick check for the points working correctly is loosen the distributor and rotate it with the coil wire pulled from the cap holding the end about ¼" from a ground. It…
Distributor was 180 degrees out. Too many prior hands in the cookie jar on this one; the car was brought to me in this state. Was raised on EFI/PCM/COP ignition, and have probably worked on less than half a dozen carbureted cars; typically it's safe to assume that a car isn't going to install its own distributor 180 degrees backwards, so it's never something I would have even thought to…