Wed Jul 31, 2013 10:16 pm
Hey guys, did a 2/3 restoration on a 1957 white grill Cub, meaning only fixed the glaring issues but gave it a complete teardown and quality repaint. Anyway, got it all together and it won't start.
Work done relevant to issue to answer questions ahead of time:
New rings and rod bearings, didn't touch valves or have crank/cam or distributor out.
New copper core plug wires, not composite or whatever they are.
Rewired per operator's manual and double checked after issue started. New regulator.
Turns over but won't start. Tries to catch and will even start a second but gas spits out of carb air intake tube (took it off to see what's going on). Spark tester shows spark to all plugs. Plenty of gas getting to it as it smells flooded. I looked at rotor and its in right. Fiddled with the timing back and fourth. Double and triple-checked plug wire locations per threads on this forum and my other Farmall Letter series tractors convinced that was the issues but they appear to be on right. I thought maybe a valve sticking but I went way beyond typical clean-up insuring no carbon was left in valve seats when cleaning up to avoid another tear=down.
I plan to check compression on each cylinder tomorrow and double check TDC with #1 cylinder and rotor location while at TDC. Should tell me if I have to tear down for a valve or head gasket seating or something. Otherwise what else am I missing? It ran fine before tear-down and repaint, I didn't touch the timing so that shouldn't be it, and rebuilt carb and had it running BEFORE tear-down so shouldn't be carb. I would think it has to be in the distributor, wires, or compression but even if a valve was sticking I've seen Cubs run on two cylinders with broken cranks and 3 would still be working if one valve happened to have carbon under it.
Thu Aug 01, 2013 6:51 am
Try and pull start it. I bet that helps.
Thu Aug 01, 2013 6:58 am
Check valve tappet clearance. It that's not the problem then the compression tests.
Thu Aug 01, 2013 12:39 pm
I second what Jason said above. If you have triple and quadruple checked the timing and plug wire location and are not getting a backfire when you try to crank it, then I am willing to bet that a pull start for the first fire will make it start right up. Merlin did just that every time that I tore into the engine (twice) and after a pull start the first time, he would then start right up on the first pull of the starter with no choke.
BE CAREFUL when pulling and only hook to the drawbar on the rear when you are pulling. Put the tractor in 3rd gear and have the person pulling you go really slowly and watch you at all times. If the tractor comes to life, make sure that you don't run up on the rear of the pulling vehicle...
Be safe, but give it a shot!
Thu Aug 01, 2013 5:29 pm
Sounds like intake leak possible.
Thu Aug 01, 2013 8:23 pm
I've pulled my fair share of tractors and always park them close to a hill "just in case". Didn't have much time to work on it tonight but did find the problem. Started with compression test to ease my mind and no compression on cylinder 3
. Reluctantly pulled the hood and was thankful I tap all threads upon reassembly on my restorations. Looked down the plug hole before I pulled the head and stuck valve (one closest to the rear of tractor). Tried to lightly tap it to see if I could get lucky and not have to pull everything off to get head off but it was tight. It worked fine upon reassembly so don't know if it was carbon that snuck in or antifreeze sneaking in and seizing it since reassembly or what. I shot gas in there through the plug hole and slowly got it to budge trying not to damage valve. Worked it up and down about 10 times tapping it lightly with a soft punch then turning motor over to push it up. Finally it just popped back down right and worked. Hit the starter without the hood off and it fired right up and ran right. Ran out of time with work tomorrow to get it all together but it ran decent. Now I can tune in the distributor perfect and watch the new paint smoke off the exhaust as I get it all tuned in and try. Worst part is over though.
Thanks for the help. I guess the least I could do is show a before (month and a half ago) and after pic of it. First actual Farmall Cub I've redone in 10 years. Tried something new and did some parts in blue including making custom covers in blue just to change it up a bit. Did a bunch of Cub Cadets and other big tractors but missed having a Cub. Enjoyable little underpowered things to rake hay and mess with.
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Thu Aug 01, 2013 9:53 pm
Glad you got it figured out!
You did a nice job on the paint, so hopefully it will now run as good as it looks!
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