48 8N runs for 10-30 seconds, then stalls too easily...

figure its time for a new thread, because I've moved on to the end game here.

1948 Front distributor 8N, with a 12V alternator, coil, and starter..

history to date... son overheated, dumped coolant all over ignition, AND fried the starter... in process of sorting that out, I discovered some baked wiring, so rewired most all the tractor, this time using a shorter piece of high temp 10 gauge for the alternator wire, and marine grade ring terminals with the thermal shrink sleeves that glue onto the wire insulation.
New (all for reasons)...
[list:5c2115a071]radiator, hoses
battery, cables
starter, wiring
points plate
spark plugs
fuel bowl+valve assembly at the gas tank
fuel screen at the carb
[/list:u:5c2115a071]



Someone suggested I check ignition current. I hooked my DC ammeter up to the coil circuit, and when the engine stopped with the points closed, I saw about 2 to 2.5 amps static current, so I bypassed the 2 ohm resistor, now I'm seeing around 4 amps static when its cold.so cranked it again a few more times, first at zero throttle with choke, then about a third throttle and it fired and this time ran for nearly 30 seconds before it died. with the resistor bypassed, the running ignition current was about 1.8 amps.


current symptoms, will crank and start and run 10-30 seconds then stumble and stall. is likely running rich as I smell and see a lot of gas fumes in the exhaust.

Its actually easiest to start at zero throttle and full choke, will start after a couple seconds of cranking, but stall if you release the choke. I probably need to turn up the idle jet (I know, tis backwards). and it will also start, without choke, somewhere around 50-60% throttle, but it tends to stumpled out.

I compression tested the motor cold and had around 120 PSI in each of the 4 cylinders, seemed pretty consistent.

wondering if I need to take apart and clean the carb, fresh gaskets and stuff ?

OK, let's start backwards from your post. Avoid guessing, a true root cause problem solving method is needed for any problem. Also avoid buying new parts and just start replacing everything in sight. Parts can be rebuilt and/or tested to determine if good or bad. Next, your compression is fine, leave it alone, not your problem. Did you perform the Fuel Flow Test? Yes? Carb is fine, leave it alone, unless, you see gas leaking all over. Remove the rubber hose from the air intake to the carb. Is it all wet with gas? No? Leave it alone. Yes? Can remove and rebuild carb -float and or needle may be stuck. Remove any added external fuel 'filters' -not needed. Is you fuel line stnd OEM 1/4" steel? No? Get one. How did the starter get 'fried' from coolant overheating -it's not even close to the radiator? I can see frying out the distributor if it got wet all over. Overheating is usually from overfilling, underfilling, and/or lack of using a thermostat -see post above. It can also be caused by improper fan belt tension on the generator or alternator. A 12V alt requires a different belt than what your generator uses. If you don't have a belt tensioning device, no matter if a generator or alternator, that was your first mistake. Your Root Cause Problem was most likely due to mucked up wiring from your 12V switch over job. Next, your front mount distributor needs to be timed correctly AND mounted correctly -here's where your ESSENTIAL MANUALS are needed. Points gapped at .015", plugs gapped at .027", timing set per instructions in Manuals all done on your bench. You can test the unit BEFORE you mount it -seek out Bruce(VA). Mounting the front distributor requires a specific way -get it off 180° and you bust the aluminum base rendering useless junk. Firing order is 1, 2, 4, 3 CCW. You say you Many a shadetree mechanic figures he knows how do a 12V job and most are done incorrectly. First, get the WIRING PICTOGRAMS by JMOR to use as your roadmap for the project -OEM Manuals never had used 12V, never had a need, therefore never had a manual on them. The 8N w/front mount, when doing a 12V job, requires a 12V GRP 25 or 35 battery; removing the generator AND the Voltage Regulator (did you do that?; using the OEM Ballast Resistor in the circuit (did you do that?); mounting a 12V alternator (1-Wire DELCO is best)and the new fan belt and belt tensioner. There was no need for you to invest in a 12V starter (how do you know it is 12V -test it?)as starters don't care if 6V or 12V. FORD 8N starter motor has 3-Wires with the Solenoid attached on it. There is no use adding an external resistor if your coil is 12V -again, here is where JMOR's Pictograms are needed. I advise to disconnect power from the battery. Disconnect any lights - lights were never a factory installed item and often wired up wrong by guys. You can reinstall once problem is solved. Start all over with the wiring per diagrams. Remove rebuild and test distributor -see Bruce(VA). Look at the base. Is it all busted up around the cam? No? it was mounted correctly then. Remove gen and VR, install new alternator, fan belt, and tensioner. Use your OEM wiring diagrams for correct 6V wiring -you need to keep the ballast resistor, ammeter, ign switch, and modify some wiring. Finally any Fuel Testing needs to be done with engine COLD not running, and never mess with any spark arcing if fuel is all over. See if this helps ya.


CORRECT FORD 8N ELECTRICAL SYSTEMS - 6V & 12V:

*PICTOGRAM courtesy of JMOR

FORD 8N TRACTOR WIRING DIAGRAMS:
PRIOR TO S/N 8N-263844:

FORD OEM BALLAST RESISTOR -USED ONLY WITH FRONT MOUNT DISTRIBUTOR:

EXTERNAL 1-OHM CERAMIC RESISTOR - USED ON FRONT MOUNT AND
ONLY IF COIL IS 6V:

FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:

Tim Daley(MI)

You could have a spark issue.


You could have a fuel issue.


Don’t guess. Troubleshoot. See tip # 13 at the link below.


As soon as it stops running, not 5 minutes later, you need to answer 2 questions before you do anything else:


With the bolt in the carb bowl removed and the gas on, will the fuel flow fill a pint jar in less than 2 minutes?


Next, get out your adjustable gap spark checker * , open the gap to 1/4", hook it up, turn the key on and crank the engine. Does the spark jump 1/4"? Post back
with the answers.


And do not buy a new part for the tractor until you can answer this question: how do I know the part on the tractor is defective?

And finally..........did you set the point gap? If so, what gap?

Once you narrow the problem to spark or fuel, post back and tell us what you found (and how you found it) and you will get plenty of help to get your tractor
running.


* Don't own an adjustable gap spark checker? Buy one! Not a test light! Until then, take an old plug, open the gap 1/4" ground it to the head & look for spark.
It’s not the color of the spark that counts; it’s the distance it jumps.

https://www.autozone.com/test-scan-and-specialty-tools/ignition-tester/oemtools-adjustable-ignition-spark-tester/10257_0_0?
cmpid=PLA:US:EN:AD:NL:1000000:TLS:71700000043798748&gclid=Cj0KCQiAovfvBRCRARIsADEmbRKBdAvAmtFfOvYiYXR7T6NYiW57uyv5-
dEKjVT_h2KogQNUUMsRixYaAlU3EALw_wcB&gclsrc=aw.ds
75 Tips

(reply to post at 04:38:05 09/12/20)

Click to expand...

FYI...

I replaced the points plate in the distributor, because the screws that hold the points in place were stripped and would not hold the points so they were floating all over the place. The points are gapped 0.015" and static timed per the diagrams I've seen.

I replaced the starter because the Bendix was all Frozen up and it wouldn't crank..

I replaced the ignition switch because the old one fell apart when I unscrewed the terminal.

I replaced the radiator because the old one was completely clogged up and beat up, might even have been original. Since it was getting a new radiator and the old hoses were crunchy I put new hoses and a new thermostat in it

I replaced the fuel bowl valve assembly because the old valve leaked, and the screens and stuff in the old fuel bowl were all rotted away.

I replaced the right angle brass fitting that feeds into the carburetor because the screen was completely clogged up, and attempts to clean it with a toothbrush and solvent did nothing.

I replaced most of the wiring because the old wiring was crispy and generally awful looking, I used high quality pure copper stranded wire with uv/oilproof insulation and Marine crimp connectors for the ring terminals and stuff.


I'll do your tests later today and get back to you.

(quoted from post at 04:38:05 09/12/20) ...
As soon as it stops running, not 5 minutes later, you need to answer 2 questions before you do anything else:


With the bolt in the carb bowl removed and the gas on, will the fuel flow fill a pint jar in less than 2 minutes?
...

Click to expand...

so I figured I'd get that plug out and check the fuel flow rate before I mess around with it hot... pull the plug, turn on the fuel valve, and just a steady drip-drip-drip, not even close to the rate you say, hey, WTF. pull the glass float bowl off, oopen that valve, drip drip drip, same thing. hmmmm.

climb up, look in tank.


please don't laugh.




it was nearly empty. added a couple gallons from the can holding the gas I'd siphoned out before removing the hood and replacing the glass bowl last month, and check the flow rate again, steady stream. had a enameled metal camp cup handy that I've been using for gas, by 20-onethousand, it was nearly half full, I figure thats close enough to a pint in 2 minutes, so shut the fuel off, replaced the bowl plug, turned fuel back on, turned ignition back on, zero throttle, full choke, crank for 2-3 seconds, starts, and runs, start to let off on the choke, nope, gonna stall, so more choke, slowly bring up throttle to about 40%, and then let off the choke, runs fine, albeit smoky, crank it up to full throttle, and as the exhaust starts to get hot, lots of water boils out of it, and pretty soon its roaring away clean as an old beast will run.


yeeeee-hah.



ok, you can all laugh at me now.