Rebuilt Farmall Cub has Fire but won't start

[ovrszd]

what do u think about the pantronix fireing where it fires faster

I know nothing about that.

 

[Briggsman4188]

it just does away with the points makes electronic ignition

 

[Briggsman4188]

it will through more fire i think another problem is its a six volt system the battery gets weak fast

 

[Briggsman4188]

if the compression is right, it should crank on the first cpl rounds but it takes more rounds to crank thats why i been pulling itr off too get to crank to make the cyl get warm

 

[Citydude]

Chucky 2009 on you tube changed his to electronic. He switched to 12 volt as well. Might check out his channel.

 

[ovrszd]

Pull cranking results in stronger spark because power isn't being used by the starter.

It also turns the engine faster which better overcomes any fuel issues.

Plugs are new?

 

[Sonny580]

The transistor ignition will NOT work on ALL cubs.--Be smart, put the good ole' points in!!! ---I had to!!! ----Also compression has to be at least 90,--110 , 130 is best. thanks; sonny580

 

[LouNY]

With that low of compression I'm surprised that it starts even being towed.
If the cam is timed correct, how much are the ring gaps?
Are the ring gaps staggered?
Starting and dying is unusual if its keeping spark and fuel.

 

[ruffdog]

I don't know this engine at all, but was anybody into the timing chain or gears? That compression is way too low. Right sized pistons installed? Leave the valve clearance at .015. Ethanol gas won't prevent it from starting. Stick with the standard ignition system. Start changing things and you introduce too many unknowns. It should start run on 6 volts. I think you have multiple issues to deal with.

Yep, I agree.

 

[DJ54]

Did you check to see if there was enough cylinder wear, to justify a re-bore kit..?? I'm not really seeing a tell tale lip at the top of the piston ring stroke, yet, I am seeing some wear. In the second picture, on cyl. #1 there appears to be a couple decent vertical gouges. Personally, if it were me, that right there would have told me to have it bored to clean that up, or which ever cylinder was the worst, and get an over sized piston kit. If the cylinders were honed, I'm not even seeing a decent cross hatch pattern. It does appear either the hone was held in one spot trying to clean up some grooves, where it looks like the pistons have stopped, in their normal 2 places they would stop, when shut off. Circular grooves in 1 & 4, and 2 & 3 cylinders match, as they should. The color difference in the bore tells me there is some wear there. At the very top is the original bore size. Just below that shows the wear where rings have worn it. And further down, shows where the hone made contact. The dark area just below the original bore tells me that is where the hone rode on the original bore, and brighter area below that dark streak is where it also made contact, bridging across that top 1" or so of worn area.

If you have that much wear, plus the gouges in #1 cylinder, and put standard pistons & rings back in, I'd have to guess that's where your compression loss is. Even with soft rings like Hastings brand, which we always used, it would take a good while to set themselves in, with a lot of run time, if ever... It's much better to have the rings wear, rather than putting chrome rings in, and wearing the cylinder bore. Until that issue is corrected, I'd venture to say you'll have to resort to starting it, like you have been.

As far as the carb., sounds like the float could use a little tweaking to get it set top a proper level. The specific gravity of leaded, and unleaded gas is different. The float will sink a little lower in unleaded gas, causing it to flood, or drip. We found this out in the mid-70's, when unleaded first came out. We were told this by a mechanic who was a pretty sharp cookie, and knew his stuff. A minor adjustment of the float, and everything worked fine.

With all of that being said, it also would depend on if that tractor was going to be put back in service to use for work, I'd imagine it would surely disappoint you on power, as they were only 9 hp. on a good day. With having compression of 30-50 psi, when it should be 120 psi tops, it'd be lucky to pull itself around, let alone any minor chores.

I'm not sure what they charge to do a cylinder bore anymore, but it used to be $50 a hole. It'd be up to you, if it's worth spending another, approx. $500 on a re-bore, and a new piston set to match.