I bought a 48 Ford 8n a little over a month ago. It started the first week I owned it but not easily. After the first week I had it the starter burned up and the flywheel teeth broke. I have since replaced both and have the tractor back together enough to try starting it. When I bought the tractor I was told it was converted to 12 volt but it still retained a generator. I decided to buy a 6 volt battery and rewire the whole tractor at the same time since all the wires were badly corroded and I followed the 6 volt wiring diagram in the shop manual. I have also replaced the coil, spark plugs, plug wires, voltage regulator, points, condenser, igniton switch .I am now thinking that fuel is my problem because when I remove the hose that goes to the air cleaner fuel runs out. What I am most concerned about though is when I bought it I checked engine compression and I had 90 lbs on all cylinders now I checked it again and have only 75 lbs on all cylinders. Is 75 enough to run the tractor? Is my drop just due to the slower cranking of the 6 volts? The last the tractor ran it backfired badly is it possible it broke a timing gear? Any help or suggestions will be greatly appreciated.
Soundguy
Old Timer
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the 75 psi is likely sticky rings from it not running.. and yes.. faster spinning will yeild higher average dynamic pressures on a compression test.
drop some atf fluid down each spark plug hole and let it set a day, then remove the plugs and roll the engine over with a towel on the head to catch any oil that pukes out.
now.. make sure that you don't have an 'extra' resistor inline from the key switch to the coil as there may have been one if it had a 12v battery. ( though there will be an oem ballast resistor on the back of the dash.. key switch connects from lower post to one o fthe top posts, and the other top post over to the coil.
Try pull starting her once you get the carb sticky flaot issue fixed, as you are probably flooding her if fuel pours out the intake.
soundguy
drop some atf fluid down each spark plug hole and let it set a day, then remove the plugs and roll the engine over with a towel on the head to catch any oil that pukes out.
now.. make sure that you don't have an 'extra' resistor inline from the key switch to the coil as there may have been one if it had a 12v battery. ( though there will be an oem ballast resistor on the back of the dash.. key switch connects from lower post to one o fthe top posts, and the other top post over to the coil.
Try pull starting her once you get the carb sticky flaot issue fixed, as you are probably flooding her if fuel pours out the intake.
soundguy
Jerry/MT
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I doubt you could have lost compression from 90psi to 75ps in a month. How did you check the compression to get 90 psi? Was the engine at operating temperature? Did you check the compression the same way when you got 75 psi?
You're kind of bouncing all over checking this and checking that. Start with checking the spark. Using an old spark plug, gap it to 3/16" to 1/4", stick it into the boot and hold it against a good ground , turn on the key and try a start. You should have a FAT, BLUISH-WHITE SPARK, THE COLOR OF LIGHTNING. If you don't have that, you gotta' find out why. worn, misdjusted, burned or corroded points, 12V coil on a 6V system, burned out 6v coil on a 12v system, bad condensor, etc. Something in your primary igntion circuit isn't right. if you havve the requisite spark,next check the timing and the firing order to make sure they are correct. If ythey are correct, move to the fuel system. open the tank valve and take the plug out of the bottomof the carb,holding a suitable container underneath it to catch the gas. The gas should come out in a CONTINUOUS FLOW not dribbling or intermittnet. If it doen't you've got an obstruction in the fuel delivery. Check the screen in the carb elbow and the filter in the sediment bowl. Check the tank vent for obstructions.
you said the electrical system was changed to 12 V with a generator. Is the genrator in fact 12V? Was the coil changed to 12V or was a resisitor put into the primary circuit with a 6v coil to limit the primary current? If that resistor isn''t there, then the coil could be damaged.
Conduct these checks in the orer that I've given you one at a time. If you find a problem, fix it and see if the tractor starts. if not move on to the next step. If you do this systematically, you find the cause of the problem.
Egon
Epic Contributor
There are additives that could make this happen!
I checked the compression both times with all the plugs removed and the engine cold. I only have the resistor mounted on the dash. I did get my carb cleaned tonight the main jet was clogged and at least it is not flooding at the moment but still will not start but it at least sounds like it is trying now. As for spark one time I check it is a blue spark then it seems to just be a orange spark. I did put a new set of points and condenser in and gapped the points at .025. The coil is now a 6 volt that I bought new but it did have a 12 volt on it. I personally do not think the generator is a 12 volt but how can I for sure tell? As for the fuel tank I have the whole hood, tank off of the tractor now and I am using a bottle with fuel in it hanging above the tractor. I am going to try the ATF fluid down all the cylinders yet tonight and when I get home from work tomorrow check everything else. I will let all know what I make out. Thank you for the advice.
Jerry/MT
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Does the voltage regulator have any markings on it that say 12 V ? otherwise you'll have to look for a data plate on the generator. Chances are that it's a 6V. Usually 12v conversions use a Delco 10Si Alternator.
An orange spark is not good. Needs to be a FAT, BLUISH-WHITE SPARK.Do you have a front mount or a side mount distributor? The front mount requires an 0.015" point gap as I recall and the sidemount is 0.025".
You might want to go to Yesterday's Tractors (Antique Tractors - Yesterday's Tractors : Antique Tractor Headquarters) and get on the Ford N forum. Those guys have a bazillion years of experience on the N series Fords and they can provide more help than I can on the old Fords.
Soundguy
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front mount points gap at .015
6v coil on 12v needs oem resistor plus another to reduce current to 3-4a. 6v coil on 6v just needs the oem resistor.
soundguy
6v coil on 12v needs oem resistor plus another to reduce current to 3-4a. 6v coil on 6v just needs the oem resistor.
soundguy
DiskDoctr
Platinum Member
Try hooking up a temporary gas tank (old lawnmower?) and line to the carb. These are notorious for getting gunk in the tank and the little screen in the bottom of some tanks.
It acts like a carb problem, including using the choke to run, then it stalls it, then it runs it, etc. Inconsistent fuel delivery.
In any case, it will eliminate one variable and is easy to do
Good luck.
- JC
It acts like a carb problem, including using the choke to run, then it stalls it, then it runs it, etc. Inconsistent fuel delivery.
In any case, it will eliminate one variable and is easy to do
Good luck.
- JC
I had a 1952 do exactly what you state in your post. I worked on it and cleaned the carb it didnt work . Took the carb and cleaned again and found the little jet in the float bowl had some rust in it . Man this is a little jet about the size of a bb . Check it out it will probally fix your tractor.