Crank no Start

[ben_dover]

When I crank my 1971 3spd manual 302 v8 mustang, for some reason she just wont turn over/ stay on.
New battery
New ig coil-12v to ig coil positive/ negative when key in run pos
New distributor/rotor cap, s. plugs, s. plug wires- set points to .017" dwell set to 28 degrees and static timing set to 6 degrees btdcc on cyl# 1 (front left cyl if facing towards car) as specified by ford for a single vacuum advance distributor
Fresh 89 ethanol free fuel is being delivered to a clean eddlebrock 1406 carb with float height/drop set to eddlebrock spec
Blue spark present on all 8 cyl by grounding s. plug when cranking
Car was running/ idling before it shut off and never turned over after 5 miles of driving since purchase
Here is a video of how the car was idling when i recieved the vehicle

No need for a compression test after hearing and seing the condition but thats coming next, not sure if anyone has compression spec for a 1971 302 v8
Any help would be greatly appreciated.

 

[midlife]

Check for bad ground and starter cables, as when you crank the starter, high resistance will drop the voltage enough that you can't keep the engine running after the key returns to RUN position.

 

[mjlan]

So the starter motor spins the engine fine it just won't fire and start running?

Are you getting any cylinders to fire? If yes are they maybe sneezing out of the carb or popping into the exhaust?

When you say "it shut off," do you mean the engine stalled on its own, or was the ignition turned off?

 

[ben_dover]

Yes Mjlan car stopped idle on its own, car starts fine just wont stay running, car will "sneeze" atomized fuel out of carb if I crank engine multiple times, and at times it will sound like engine rpm surpassed starter motor rpm-( starter motor disengages with exhaust headers going from cold to lukewarm.)

my apologies, Voltage at + of ig coil is 3.9vdc with key in run pos
disconnected 3 pin connector going to oil pressure sw, temp sw, ig coil + and found 12.5 vdc on ig coil/ 12.5 vdc temp sw, 11.5vdc on oil pressure sw wire
red/ green wire on connector to ignition coil + shows less than 1 ohm resistance? Why am I loosing so much voltage after the connector if ignition coil + wire shows good continuity.

 

[mjlan]

The points can't tolerate battery voltage for extended periods of time so when the key is in 'run' the coil is powered through a resistor wire to lower the ignition primary voltage. There should be a plug on the 'S' post of the solenoid- this 'S' post is energized when the solenoid is closed and this wire sends battery voltage to the coil during starting to increase ignition energy during starting. I should clarify- there isn't a second wire running to the coil +, but the wire from the solenoid 'S' terminal is spliced into the coil + wire in the car harness somewhere.

So you should measure lower voltage at the coil + with the key in 'run' and battery voltage at the coil with the key in 'start.'

Are you measuring roughly battery voltage at each circuit of the car side of the temp/OP/coil feed connector? I don't think that is correct, I think those should be a lower voltage but I may be wrong on that, perhaps somebody else has a better understanding?

If it was me I would temporarily hot-wire the ignition to convince myself that there wasn't anything wrong mechanically with the engine. Run a jumper wire from the + side of the battery to the coil and then jump the solenoid. If the car runs this way then you know you have an issue in the coil power feed circuit somewhere.

 

[Horsin' Around]

Which 302 firing order do you have? Is your engine original? Early 302's 1-5-4-2-6-3-7-8, later firing order was changed to 1-3-7-2-6-5-4-8. Determined by cam. Did you swap wires 1 at a time or all together with new cap?

 

[ben_dover]

Found the issue, the helical gear inside the engine where the distributor sits/ meshes is rotating intermittently and not in sync with crankshaft rotation.

 

[Steve McMahan]

Yikes, that weird. Sounds like the pin that hold the gear to the distributor drive shaft is gone or broken. Might be an easy fix. I would examine that gear carefully or even replace it, since if it’s loose, the meshing action might have damaged it. Ditto on the cam gear. Others with more knowledge will like also comment on their repair course of action.

 

[ben_dover]

Okay, so I can get the distributor drive gear to rotate, counterclockwise and then clockwise but after a couple turns the gear will slowly stop rotating. No damage or excessive play on old/new distributor and same goes for the distributor drive gear.

 

[Hemikiller]

If the gears aren't damaged and the roll pin in the distributor isn't sheared, then it sounds like you need a timing set.

 

[mach1sc]

Okay, so I can get the distributor drive gear to rotate, counterclockwise and then clockwise but after a couple turns the gear will slowly stop rotating. No damage or excessive play on old/new distributor and same goes for the distributor drive gear.

sounds like you are describing a distributor gear rotating on the distributor shaft. that is the whole purpose of the pin going thru it to keep it in one place so your rotor stays in time. get a new distributor or replace the pin.

there are about two things that will shear that pin, 1 the oil pump gets in a bind. and 2. the distributor gets in a bind .

sometimes a screw formerly holding down the points or capacitor falls below the points plate and binds in the weight area of the centrifugal advance so if you have a slipping gear remove the points plate and check for crap under it. along with replacing the pin. or just buy a new distributor but still look under the points plate and clean out the shavings even on a new distributor. sloppy manufacturing processes you know.

 

[cjstaci]

I had a roll pin break back in 1977 on my 429 Torino cobra. It happened on the freeway. Towed the car home. At first I thought it was the timing chain but found it was the distributor gear. I replaced the pin and it was fixed. I was 17 at the time and knew enough about repairing cars to be dangerous, basically ignorant, lol. I didn’t know why the pin broke but guess what, it did it again but this time there was a difference. I don’t remember how but I found the oil pump was jammed. I found a broken piece of the roll pin in the oil pump. I removed it, cleaned the oil pan, put it back together and it never happened again.