# 1948 Cub



## farmallzach (Feb 10, 2010)

I have been working on a 48 cub, bought last fall with the motor stuck for $200 and it had brand new tires and a belly sickle mower. I got it home and got the engine unstuck and then cleaned it all up and oiled down the engine and put in the back of the barn till I could work on it. Ive had it in the shop for a month now working on it. Put new rings in it and cleaned the motor all up, all new gaskets and everything. But the problem is I still cant get it started any ideas? Im getting plenty of fuel to it too.


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## Hoodoo Valley (Nov 14, 2006)

And spark I gather? Is the timing on?


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## farmallzach (Feb 10, 2010)

yeah its on time and i got really good spark, all the wiring harness on it is all riged up that wouldnt have anything to do with it would it?


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## avmcalister (May 15, 2004)

I have a similar problem with my 49 cub.
It must have three things to start, Gas, spark, & compression. If it gets these in the right order it will run. 
I know this is an old thread so if you have it running please let me know what you did so I might try on mine and get it going.

The Big A


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## Paul5388 (Oct 9, 2007)

That's what it takes in its simplest form, but there are other things to consider. 

A simple check for compression is to remove all of the spark plug wires and remove one spark plug. Stick your thumb over the hole and get someone to crank it over a little. It should have enough compression to blow your thumb off of the hole, just like on a lawnmower. 

The normal firing order of a 4 cycle 4 cylinder engine will have one cylinder firing while it's opposing cylinder will be between intake and exhaust. With the valve cover off, watch for the cylinder that is between intake and exhaust when the timing mark indicates TDC. If valves on #1 cylinder are opening and closing, rotate the engine one complete revolution. You can check valve clearance on #1 in that position. You can also check to see if your spark is anywhere close to TDC and know which is the opposing cylinder.

Back the engine up from TDC on #1 firing stroke, put the plug wire on #1 plug and with the plug out of the hole, ground the hex portion, with the key on. When the engine is turned back toward TDC, there should be a spark at the plug close to TDC. If not, the cam timing is off, the distributor cap is wired wrong or the distributor timing is wrong.

An engine won't run if the exhaust, or muffler, is stopped up, even if there is fire, compression and fuel.


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## avmcalister (May 15, 2004)

It will fire if the exhaust is stopped up.Something is going to give, it will blow it clear or burst something. It is an explosion that is fairly powerful.
AAm


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## Paul5388 (Oct 9, 2007)

A completely clogged catalytic converter will not let an engine run. It will possibly fire one cylinder, but without a place for the exhaust to go, the engine won't turn to let the next cylinder intake fuel. The pressure will just leak past the rings as it sits there dead headed. It's the same principle as having all the exhaust valves adjusted where they won't open.


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## farmall2009 (Feb 3, 2009)

Two things to check on this tractor:
1. Intake manifold gaskets. make sure you used new gaskets and that the mating flange to the block is nice and flat. Because of the up draft carb you have to make sure you have no intake leaks.
2. Do you have the original IH carb? These are notorious for having warped housings therefore sucking too much air. The replacement is a much better Zenith carb. (which cured the very same problem on my tractor.)
Also you didn't mention if you're running a 12 volt battery. That makes these little guys crank and fire a lot better.


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## avmcalister (May 15, 2004)

I am not an expert on gasoline motors. I have never seen a tractor with a catalytic convertor. This is the last time I will respond to this subject. I never intended to get in an argument about this.


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## avmcalister (May 15, 2004)

Thanks Farmall2009
Just saw your response, that sounds like it might be my problem. I will try it at my first chance.


AAm


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## avmcalister (May 15, 2004)

Hey Farmall2009
I took the carb off and cleaned good put a little gasket sealer on the gasket and it started.
Couldn't run but a few seconds because don't have the cooling system up and running yet.

Thanks for the info


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## Paul5388 (Oct 9, 2007)

Well, it wasn't meant to be an argument, it was an illustration of what happens when a dirt dobber builds in your exhaust and stops it up. 

I just assumed you had fuel to the cylinders, since you are the one that mentioned it being a necessity.


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