DC won't run

We've got on a DC tractor, with DC stationary
unit block, and a Tractor head:
Good valves, all adjusted .012 clearance.
Spark to the plugs.
Compression in all cylinders.
Clean carb (won't run on ether, or gas placed
in cylinder like they did before ether).
6V starter, cranking on 12V.

Any thoughts as to why we can't get it to run
after swamping out the head from a tractor onto
a Power plant block?

Thanks
 
Knew I'd forget something on the list, Mag has never been off, and it ran before the swap due to a water leak leaking head.

Thanks all the same, keep the guesses coming!
 
Well, the wires are hooked up by the order cast in the block, so they are correct.

If knew the head would come back off without damaging the head gasket, would consider putting the other head back on and trying to start. But at $100 a gasket, not wanting to do all that work with the risk to the gasket!
 
I've seen plugs so fowled, they would not fire. Double check your wires. #1 wire to # 1 plug comes out of the Mag Cap @ the 1:00 O-Clock tower. Next, going around clockwise, about 5 o_clock, the wire goes to #3 plug. On around clockwise to 7 o-clock & the wire should go to #4 plug & up at 11 o-clock should go to #2 plug. I cannot think of what you could find by pulling the head.
How are the intake manifold gaskets?
 
One time I rebuilt an engine and could not get it to fire after checking all the usual stuff. An old mechanic told me to squirt some oil into each cylinder through the spark plug hole. It started up instantly. He said it wasn't getting enough compression to draw the air/fuel mix into the engine. All I know is it worked. Don
 
Will give it a try. The though on pulling the head is this: It ran with head A that has a water leak. Doesn't run with head B. Both have good valves and manifold gaskets, don't think there's any way manifold could be plugged up with rust, and its not sat with out carb. Just annoying it ran with the leaky head, but won't with a better one (that we've never seen run!)

Though some here on YT don't advise pull starting, may try that, just to see.
 


If you get it going reset the valves to .018 cold, unless you have a reground cam and your grinder tells you otherwise that would be the factory setting. That is however not why it's not running for you. If you have access to a compression gage take the compression. If the engine ran before it should run now. If you used the old plugs out of the other head I would replace them with Autolite 3116 and verify the firing order is correct. Does it have a mag or distributor and do you have good spark at the plugs?
 
Keep us posted. I think it's something simple. If you haven't yet, pull a spark plug & check spark there. If they are Champions, trash them & install Autolite 3116. If you pull start, use 4th gear, engage clutch slowly. Very hard on the ring & pinion because it's on the input shaft.
 
It is a mag, fire order is correct, and in time
verified by rotor location and #1 TDC. What is
ideal compression range on DC?
 
I am not a dc exspert but is firing order and rotor button going in the right direction????? What about valve spring issues?? or rocker arm issues??? This piston coming up would give some compression anyway. What about leaks in the intake gasket???? And last what about it taking in water/antifreeze in the combustion chambers??? ALL THE ABOVE HAS PUT ME DOWN FOR THE COUNT.
 
All internal combustion engines needs three things to run. Fuel/air mixture, compression, and a source of ignition. Sounds like you have the fuel and ignition covered, so there has to be something going on with the compression.
 
If you put your hand over the carburetor air intake when the engine is cranked over, do you feel a vacuum? If you don't, the valves are out of time with the pistons.
 
Possible bad coil in the mag. I know you said you have spark but is it enough under compression? Sounds weird but I see it in the automotive world. Are the combustion chambers in the new head the same?
 
my guess is the same as everyone else's. your out of time. everything is probably exact as needed except the mag is 180 out. double check tdc and see if your on the exhaust stroke. no cylinder will fire on exhaust stroke, not even with ether. how was this possible? someone previous put the mag on wrong and reran the plug wires. now you have everything correct it don't work. very easy test. pencil mark a line on the mag and housing to realighn the timing. remove mag, turn 180 backwards and reinstall. please give it a try! chuck
 
was it starting on 12V prior to working on it? I've heard of engines with mags that wont start on 12 because they spin to fast for the mag to create its impulse. If not that then I would say that your plug wires are 180 degrees off on the mag.
 
I know this is frustrating for you but kind of fun for us to hear all the opinions. Could you please report what finally works to get your DC running? Thanks, Don
 
John touched on this, but just to pull it out in a separate post...........
Are the wires in the mag (you already said in the correct firing order) but.... GOING IN THE PROPER ROTATION ON THE CAP ??????????
 
Maybe the cylinders and plugs are too wet.
There's been times when I've had to remove all the spark plugs and then crank the engine over a few times to blow out the cylinders. Then dry the plugs and put them back in. You can wash fuel and oil off of the spark plugs with a shot of ether. That works pretty good.
And like was said you may need a different set of plugs.
I've had old stale gas that was so bad that an engine would barely start or wouldn't start at all and ended up with flooded cylinders and wet fouled plugs.
 
Desert eagle hit on a problem I had with my SC once. Ran perfect one day and the next, nothing. Tried everything and nothing worked. Had spark to the plugs but would not run. Put in a new set of plugs and fired up instantly. Old set of plugs would not fire under compression anymore, go figure. Just another piece of information. Good luck, Allan.
 
Hi David swap your #2 and #3 plug wires at the head it takes less than a min. I'm sure we all have done this.
 
Doing a vac 1947 and couldn't get tractor to fire did electrical test starting at ignition switch and found that a brand new switch was at fault, check circuit all the way thru. Get number 1 cylinder top center on combustion stroke, rotate engine, half turn clockwise and do number 3 cylinder, rotate half turn do number 4, rotate half turn do number 2, if rotate one more half turn should be back on number 1 cylinder, good luck maybe one of many ideas will work. 47 vac is running fine and waiting for some warm weather to finish up tractor as far as paint
 

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