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Good Times!
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Discussion Starter #1 (Edited)
How loud is the snap with a Fairbanks mag compared to a Wico?
I'm asking because I'm trying to get my '69 SC going again after a clean up, degreasing and paint job but all I get is a sputter, some back firing (very light) and a dead battery:banghead3!
Before I took the tractor apart, it ran fine, a little rich but fine. The head, carb and mag never came off or was even moved during the clean up.
I covered all the holes and mag to keep moister out.


So far I've cleaned and gapped the points and checked for moister and found none.
Replaced the condenser 8 months ago, so it should be ok?
New Plug
I'm getting fuel to the carb the same as before (it still drips some if I leave the valve open under the tank)

Things I'm having trouble understanding:

I did a compression test and was only getting 32 psi. This machine had NO problem with power before the clean up. So I removed the head and inspected and cleaned up some just in case a piece of carbon was stuck on one of the valves or seats. I saw nothing stopping the valves from seating correctly. They were fine.

I also looked at the cylinder and found it to be very smooth/clean and with NO variance in diameter, I mean the gage never moved, so it's perfect, top and bottom. Although I don't know about the rings, they should be fine, right?

I didn't see or feel much oil on the cylinder wall. I'm getting oil from the pump, through the filter and into the fill area up front but it's not a lot and my oil gage never gets out of the red (thats a symptom of low cylinder pressure, right?).

So, I'm left with spark or lack of. Is this a good spark? It's blue but it does seem that big to me and what I noticed while turning to TDC was there was no loud snap from the mag.

http://www.youtube.com/watch?v=LXZz7kLoaWE

So what should I do next.

Thanks
Paul
 

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Old Iron Connoisseur
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2,785 Posts
I've found with the electric start on our C, Bumping the starter seems to work better as opposed to holding the button in. Almost like the starter can spin fast enough to make the impulse drop out but not fast enough for the magneto to make good spark. Not sure but what we've found with our one electric start tractor.
 

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Good Times!
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236 Posts
Discussion Starter #4
Is there any rust on the exhasut valve seat?
None at all. They were both very clean and chiny. There was some carbon build up on the top of the piston and on the head it's all black, so I cleaned it up and vacuumed it twice before putting it back together.
 

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Arcam and HH could be right, add some oil to the cylinder and try to start the engine. If it cures itself it was probably carbon, if not, it may require a valve adjustment.
 

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Good Times!
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236 Posts
Discussion Starter #8
Quote:
Originally Posted by helixhippie
Re-check your valve adjustment
Will do!

That was going to me my next sugestion.

What about your head gasket, is it new or used?
Used

Ok on both, isn't it strange that the gasket went bad or the valves got out of whack while I just cleaned and painted it?

So the spark looks OK?
 

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Good Times!
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236 Posts
Discussion Starter #9
Arcam and HH could be right, add some oil to the cylinder and try to start the engine. If it cures itself it was probably carbon, if not, it may require a valve adjustment.
Thanks - I've added oil twice, once in the beginning when I notice the low oil pressure and once again when I took the head off to inspect and clean around the valves and check the cylinder.

I'll look at a valve adjustment tomorrow, thanks!
 

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Old Iron Connoisseur
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Thanks - I've added oil twice, once in the beginning when I notice the low oil pressure and once again when I took the head off to inspect and clean around the valves and check the cylinder.

I'll look at a valve adjustment tomorrow, thanks!
I think the poster was suggesting a little oil on top of the piston. Sometimes it helps to get compression up for starting one with stuck rings or such and once the motor is going, heat and movement do the rest!
 

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Good Times!
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Discussion Starter #11
I think the poster was suggesting a little oil on top of the piston. Sometimes it helps to get compression up for starting one with stuck rings or such and once the motor is going, heat and movement do the rest!
Yep, thats why I did it, both times. The first time I just squirted oil in from spark plug hole and the second time with the head off, I coated the cylinder wall because it felt dry.

So I'm off to look at the valve adjustments go from there.
Although I still don't understand how they got out of whack by just cleaning and painting.

Is there a way of blowing out the carb without taking it apart?
 

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I'm sure you've already done this, but if not I'd recommend checking the timing and also the spark. I mean how does the spark look -- is it a nice big one or a weak little yellow flicker? Not that this is the preferred "shop" way to do it, but to get you up and running it works. Now, have you measured your cylinder bore? Because I've seen them run all the way up to 3.259 on a std bore. (3.250 is original size.) I had one tractor that the guy I bought it from told me it just wouldn't restart one day when he shut it off to take a break. Pulled the cylinder off and sure enough it was worn .010 over without boring! These things are very simple, but they are VERY frustrating sometimes. If you don't have measuring instruments, take it to a machine shop and get the bore measured. If you've got an extra cylinder/piston that you know is good, I'd try swapping for the **** of it. Not a huge job, and the more practice you get, the more you get used to it! :D
 

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Collector of many tractors
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Put air pressure to the sparkplug hole with an adapter and listen for air leaks intake and exhaust.
 

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Good Times!
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Discussion Starter #14
I'm sure you've already done this, but if not I'd recommend checking the timing and also the spark. I mean how does the spark look -- is it a nice big one or a weak little yellow flicker? Not that this is the preferred "shop" way to do it, but to get you up and running it works. Now, have you measured your cylinder bore? Because I've seen them run all the way up to 3.259 on a std bore. (3.250 is original size.) I had one tractor that the guy I bought it from told me it just wouldn't restart one day when he shut it off to take a break. Pulled the cylinder off and sure enough it was worn .010 over without boring! These things are very simple, but they are VERY frustrating sometimes. If you don't have measuring instruments, take it to a machine shop and get the bore measured. If you've got an extra cylinder/piston that you know is good, I'd try swapping for the **** of it. Not a huge job, and the more practice you get, the more you get used to it! :D
All good questions.
Here is a vid of the spark http://www.youtube.com/watch?v=LXZz7kLoaWE
What do you think?
The cylinder was re-bored to 20 by the PO and I havent had it measured . . . but the tractor was strong before I painted it???????? NO Problems, just a little rich as it would back fire once in a while and drip fuel from the bottom of the carb

I also looked at the cylinder and found it to be very smooth/clean and with NO variance in diameter, I mean the gage never moved, so it's perfect, top and bottom. Although I don't know about the rings, they should be fine, right?

Kbeitz, Put air pressure to the sparkplug hole with an adapter and listen for air leaks intake and exhaust.


I did try that and the piston wouldn't stay in place, another words the pressure forced the piston down from TDC. That must be a good thing?

I didn't see or feel much oil on the cylinder wall so I was worried that I'm not getting through the filter and into the fill area up front but I am, it's not a lot and my oil gage never gets out of the red so is low oil pressure a symptom of low cylinder pressure?

How much fuel does it take to stop the tractor from starting. I mean, could it be that it's just flooded???

Thanks for the help guys. I'm still very new to all this.
 

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take off the carburetor and spray a shot or two of ether or carb cleaner down the spark plug hole. Then try starting it. see if it pops on those shots. If it does, your problems are not cyl or valve related. If this method does not get it at least to fire after a few tries, I would still suspect cylinder/ring/valve troubles.
 

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Good Times!
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236 Posts
Discussion Starter #16
Well I reached the end of what I could do so I took the '69 to Paxton Auto, in Paxton, MA and had some real mechanics look it over. Rusty was the guy with the nice 450 with the loader and Jeff had the nice L that he rebuilt from the ground up. Both of them were a little perplexed with why it wouldn't start, but they gave me some solid trouble shooting directions to run in.

We tested spark, fuel, compression.
Spark: good! But even they noticed the silence or less of a snap coming from the Fairbanks.
Fuel: good!


Compression: Weird> It started below 40psi built up to 45/48 and as the machine slowed down, it increased to just over 50/52 psi.

We squirted oil into the cylinder and got lots of smoke, so there is some combustion going on.

Next was Timing: They noticed the mark on the fairbanks lined up with the coupling at TDC, BUT Rusty put a timing light on it and it was all over the place, I mean way before and way after the mark!

So I'll start with taking the mag apart and take'n a look around. Once I have it snapping again, I'll try it out.
Then if that doesn't work it's time to test the springs on the valves and make sure their not getting jammed up or just weak spring(s).

Any other ideas are welcomed and much appreciated.

Thanks
Paul
 

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Old Iron Connoisseur
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If the timing is all over and the impulse isn't working all the time... there is your problem. Those are tied together. Sounds like you are well on your way to figuring this thing out.
 

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Right. It sounds to me like the impulse coupling is just flailing around.

I dunno from FM, but on a Wico, there's a big spring in there which winds up when the pawl contacts the stop, then releases. I would expect there to be a similar arrangement on an FM. I'm guessing that the spring is broken or disconnected, or maybe even that the stop mechanism is busted.
 

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Good Times!
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236 Posts
Discussion Starter #19
I really struggled getting the Fairbanks apart (and it's still not apart) so I picked up a Wico for $40 and BAM! She started right up and sounded perfect :trink39:!!!
Anyone have advise on how to get out the hub from the fairbanks? I'd like to get this mag running right.

Here's a few pix:
 

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Gravelyyard.com
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Yes! Don't! If you go much further it might not go back together. Fairbanks are very tricky to disasemble, and they realy can't be adjusted. If you remove the rotor, you will weaken the magnets. Stick with the Wico, it's a much more servisable mag.
 
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