Farmall Cub Engine Rebuild

Mon Dec 17, 2012 9:43 pm

We have just got through building the engine in my 1953 cub. As long as it is ideling it will continue to run with good oil preasure. We thought that the hydraulics was building to much pressure and causing it to shut down. So we disconected the pump and put a plate on it. Started and it ideled for 30 minutes ran fine stated giving it some gas and it almost sound like the engine bearings are sezzing.but you can hit the starter and it starts back up. anyone have any ideas. thanks Mark

Re: Farmall Cub Engine Rebuild

Mon Dec 17, 2012 9:48 pm

i have had engines with a bad condensor or condensor hooked up to the hot side of the coil do what you describe. could there be something wrong with the governor shutting it down?

Re: Farmall Cub Engine Rebuild

Mon Dec 17, 2012 10:02 pm

Fan connected? Generator? Did you change bearing sizes? Install caps back in correct orientation? Is it hard to turn over by hand?

Re: Farmall Cub Engine Rebuild

Mon Dec 17, 2012 10:17 pm

I would pull the pan and see what is going on. sounds like a foul-up on assembly

Re: Farmall Cub Engine Rebuild

Mon Dec 17, 2012 10:26 pm

try choking when it starts to load down. If that helps look for a fuel problem. If not, the first tries would be points and condenser or coil since it will immediately restart.

Re: Farmall Cub Engine Rebuild

Mon Dec 17, 2012 10:45 pm

Check to see if ignition advance is working. Use timing light.

Re: Farmall Cub Engine Rebuild

Tue Dec 18, 2012 1:22 pm

cant give you any help until we know exactley what you did to the engine to rebuild it. Cylinders over bored? what size bored. correct clearence in cylinders? correct ring gap? what pistons> aluminum or cast iron? all aftermarket pistons depending on who made them have issues when it comes to fit in the cylinders. Cant go by the specks in the book. have to have piston in hand for machine shop to fit. crank reground? what size? rods rebuilt? I have bought rebuilt Blocks in the past that came with tisco pistons. upon assembly the pistons would not begin to fit the cylinders. The seller said the machine shop went by the specks in the book. well I explained that the specks in the book dont work with aftermarket pistons these days.

Re: Farmall Cub Engine Rebuild

Tue Dec 18, 2012 4:54 pm

Did you measure the bearing clearance when you assembled the main and rod bearing caps? Was the crank reground to begin with?

Re: Farmall Cub Engine Rebuild

Tue Dec 18, 2012 5:56 pm

PaulBernier 86662 wrote:Did you measure the bearing clearance when you assembled the main and rod bearing caps? Was the crank reground to begin with?


That was my first thought. If I even suspected a bearing noise I'd check the bearing clearance with plastigage. I'd do that before cranking the motor over again. Then we need the answers to Clarks questions.

Re: Farmall Cub Engine Rebuild

Tue Dec 18, 2012 6:49 pm

Well we took the engine to machine shop. It was already .30 over on pistons, .10 on bearing and piston rods. I put in major overhaul kit and cheched every thing as we went. Cleaned and checked all parts. The engine turns good by hand and even when it seems to lock up you can start it right back up or reach down and turn it over by hand. It seem like when you give is some gas it runs good but then sounds as if it is goig into heavey pull and just shuts down. I am not used to governors it could be that. But it seems if the engine was locking down it would stay locked untill it cooled and then maybe turn over. but soon as it quits I can touch the starter and it fires right back up. Thanks for any help. Mark

Re: Farmall Cub Engine Rebuild

Tue Dec 18, 2012 6:58 pm

Use a good lubricant and lube all of the links/connections in the governor circuit.

Image

If that don't help, then it is most likely a fuel supply issue.

Re: Farmall Cub Engine Rebuild

Tue Dec 18, 2012 7:37 pm

zekie1997 wrote:But it seems if the engine was locking down it would stay locked until it cooled and then maybe turn over. but soon as it quits I can touch the starter and it fires right back up.
True. Oil pressure good, engine ran at idle for 30 minutes. Engine would start locking up as it reached operating temperature and parts expanded. Once locked up - wouldn't release until cooled down - or perhaps never. If fit was over tight and engine still running, when shut off, engine would stop instantly.

My though is that the problem is some place other than engine mechanicals.

Suggest taking one system at a time. I would start with ignition. Timing light. Mark pulley on advance mark and approximately 180 degrees from advance mark. Check timing at idle and for advance on #1 and #4 cylinder using advance mark. Same with cylinder #2 and #3 on 180 degree mark (won't be exact but you can check for advance and identical flash locations for cylinder #2 and #3.).

Re: Farmall Cub Engine Rebuild

Tue Dec 18, 2012 9:58 pm

re-check valve clearence

Re: Farmall Cub Engine Rebuild

Wed Dec 19, 2012 6:26 am

Dumb thought, could you be building up hydraulic pressure due to a dead head in the Touch Control circuit?

Re: Farmall Cub Engine Rebuild

Wed Dec 19, 2012 8:33 am

Rick in his first post he said he disconnected the pump