Farmall Cub Forum -- Questions and answers to all of your Cub related issues.
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Have had my cub (1948 model) for five years now (paid $25,000 for it but they also threw in 10-acres and mobile home) and it ran great. Last year it kept quitting for no apparent reason. Finally traced it to a defective ignition switch that randomly shorted out the mag. Now there seems to be a governor problem. It will idle with no load but advancing the throttle causes the governor rod to cycle repeatedly until the engine dies? What will happen if I disable the governor? The manual says to take it to the dealer but there is no one there who knows anything about it. Any ideas?
Sweet deal on the Cub. Welcome to the forum. Don't be to hasty to blame the governor, sounds like a classic fuel starvation problem causing the governor to "hunt" till the engine dies from fuel starvation.
If the Cub has an IH carb on it, you can pull the drain plug on the bottom of the carb and check for fuel flow, if a good steady stream, then replace drain plug and pull the main jet. Run a piece of thin copper wire through the orifice. (You can use a strand of telephone wire or something comparable) Then use compressed air through the jet to blow out any remaining crud. With luck, this should cure the problem.
If you don't get good fuel flow from the drain, then your problem is upstream, either the sediment bowl or crud in the tank blocking the fuel intake. I'm sure there will be others (with more knowledge than me) that will chime in and help solve your problem.
G'day to you and hey... congrats on acquiring your '48 Cub .. very cool way to do it. 10 acres and a mobile home came free with the Cub .. gotta like them deals
Do not disable the governor
Yup, sounds like fuel starvation. Bet you dollars to doughnuts that there is either dirt/crud, rust or a flake of varnish blocking either the inlet, the small longitudinal orifice in the main jet or the cage in the carb. Solution? Well, drain the tank into a filtered container, then remove the Fuel Sediment Bowl.
Repeat the flushing of the tank with that gas until the fuel runs clear and clean. Check the Fuel Sediment Bowl and clean it. Make sure the screen if clean and not blocked with varnish then reassemble making sure the screen and gasket are installed properly.
Next make sure that the carb inlet screen is clean and there is not dirt/crud/rust/varnish blocking the screen. Then, check the main metering jet, ensure both the horizontal and the longitudinal orifices are clean. For the longitudinal orifice, use a strand of soft copper such as 1 strand of twisted pair -- aka telephone wire and gently insert the wire into the orifice. You should see the end appear in the larger orifice. After that, remove the float hinge pin - remove the needle and cage. Hold the cage up to natural light and see if it is opaque. If so there is varnish, clean appropriately. Also if there is any dirt/crud/rust - same thing. Reassemble and reinstall onto the engine. Give it a shot. Should run better now.
Also.. as part of your maintenance routine it would be a good idea to spray some sort of penetrating oil such as PB Blaster, Nutz Buster, Solvo-Rust, Kroil, Deep-Creep etc., onto all the linkages and connection for the governor. Move the governor rod a number of times to ensure that any dirt/crud that may be in some of the connections is cleaned out. See the drawing below for the points to spray - everywhere there is a joint/connection.
There is a lot of information available to our members and I would encourage you to follow the links below. Well worth your while.
Well we have done everything recommended and found some heavy rusting in the fuel tank (***!!@@** ethanol!), pulled that, cleaned it, and put in sealer. Fuel flows freely but still no joy. It starts but dies under load, that being put in gear. Also pulled the coil and cleaned the contacts. My old 8N runs like a watch so I may have to give up on the Cub. I found a country store that sells non-ethanol gas and will use that from now on but still would like to have old red running. Any more ideas?
If you're still getting good fuel flow out of the fuel bowl I would double check and re-clean the jets. Also - if there's an inline fuel filter other than the strainer I would take it out. If still no "joy" then I would check to see if you're getting good spark. It needs to be a visible blue spark, not yellow and anemic. If not a good hot spark then my guess is the coil in the mag has become weak. I'd clean and re-gap the points too. Others will add their thoughts as well. ...and as an afterthought, if you haven't already replaced them, a fresh set of plugs may be all it needs.
Kinda agree with Ray on this. If you still have no joy after double checking the fuel circuit and ensuring there is no in-line filter .... then the next obvious place to check is the spark.
Remember for combustion to occur you have to have air, fuel, compression and spark. Sounds like you now have the 1st 3 so it has to be somewhere in the spark side. Check the coil .. (is it internal or external?). See if there is a good strong blue spark. If not .. then you have a coil issue. If you have a good strong blue spark at the coil, then the next step is to check the points and condenser. Ensure the gap is correct. Check and ensure that the insulating wafers between the points and the side of the mag are there. Then check for a good spark at each of the plugs. If not then check the spark plug wires. Make sure that they are not carbon composite but are copper core. Mags don't much like carbon composite. While in there you may want to freshen up the plugs a bit or replace if indicated.
Little Red lives! The spark seems to have been the major problem. We had checked the spark and always got a nice blue one but no real joy. An in depth testing of the coil uncovered a short: apparently it was shorting out intermittently from the vibrations of the engine. You all know the price of the original type coil and it seemed a bit much to gamble that was the root of the problem. While browsing TSC I checked their chart for Cub parts. They listed a coil that also fits the 8N. So I gambled the 24.50 and came home with one. Naturally, it did not look anything like original, more in order of a '48 Chevy, but it works! No problem hooking it up although to a purist Cub owner that can hanging out the side of the engine would look weird. Bottom line, my Cub has returned to work. We decided when we get finished with a '66 VW, it goes in the garage for new rings and a valve job. Thanks for all the advice, it was a big help and we cleaned up lot of little things along the way.
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