Farmall Cub

Yeah timing is spot on, I am changing out the plug wires because the ones that are on the tractor pull right apart when you try and remove them from the cap or a plug. (you know the cheap crappy ones I am talking about) I also need to put a kit in the Carb and maybe give it a pull as I may not have enough oumph to crank her up at first.

sugarbush wrote:Yeah timing is spot on, I am changing out the plug wires because the ones that are on the tractor pull right apart when you try and remove them from the cap or a plug. (you know the cheap crappy ones I am talking about) I also need to put a kit in the Carb and maybe give it a pull as I may not have enough oumph to crank her up at first.

Use only solid copper core plug wires on a magneto.

Do you have a source for solid core copper? The sets of wires I have are all stranded.

NAPA stocks it. I bought all my spark plug cable supplies in bulk .. box of boots, 90 deg boots and a coil of copper wire. Pretty reasonable, although the wire is pricey.

TM Tractor sells two varieties also.

Bob

Yup, I keep forgetting Tom does:



spark plug wire set braided,

Very reasonable price point as well and already made up

Item description: replacement spark plug wire set braided, new, original style, made in the U.S.A., replaces 407487R1, lacquer covered cotton braid over PVC with copper core, for use with 6 volt or 12 volt electrical systems and J-4 magneto.

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spark plug wire set

Item description: replacement spark plug wire set, new, for use with 6 volt or 12 volt electrical systems and J-4 magneto, copper conductor, replaces 407487R1

SUGARBUSH----STRANDED IS THE RIGHT WIRE TO USE-------

lombard wrote:SUGARBUSH----STRANDED IS THE RIGHT WIRE TO USE-------

That's what TM is selling SB, my terminology of solid copper core is probably off, just as long as you use copper core wires you will be good to go.

Oh okay... I thought you meant solid copper instead of stranded copper core.

So today I pulled the carb off, boiled it in lemon juice and installed the new kit. I also replaced the plugs with autolites... tomorrow I will put the tank back on, prime the oil pump, and see if she will start.

Copper braid as compared to composite/carbon braid. Solid would be kinda brittle unless it was thick like hard line/coaxial cable. Maybe we should be using solid copper braid as the right term for mags equipped Cubs.

Look at this thread.....I had a similar problem with my mag and had the static timing correct but the actual timing of the rotor was out of time.
viewtopic.php?f=1&t=74472
Check toward the bottom of the first page ........the reply from Jim Becker.

Okay so the start up today was a no go. So back to square 1. I decided to actually test the compression so I ran to autozone and got a loan-a-tool compression gauge. Got home and it isn't reading anything on any of the cylinders. If feel compression with my finger over the spark plug holes and I feel it at the intake and exhaust on the manifold. So I thought the gauge was junk so I checked my snowblower and it read it just fine.

So where to start on my assumed compression issue? I don't have an air compressor so cant really pump air in to find where it is leaking out. All the valves are moving and seem to be sealing properly... that leave the rings... I pulled the head and the sleeves look good, not scored at all like stuck rings.

When doing the compresion check did you do it twice? Onece dry and the second time you do it put about a table spoon of oil in each spark plug hole. This should help seal the rings and not let as much air pass by into your crank case. If still no preasure on the gage then you probubly have valves that an not seating.

Yeah I checked it dry and wet and got 0 psi on all 4 both ways. I don't understand why the compression feels good, but not showing on a gauge?

sugarbush wrote:Yeah I checked it dry and wet and got 0 psi on all 4 both ways.

Valves not sealing.