model A 1950 starts when cold, stops when warm

[Mark Pengelly]

I"ve scoured the forum to find something like my problem which is that when stone cold the old girls fires up fine. All appears to be well. Ignition timing, spark, carb all seem OK. After running for about 5-10 mins it all goes pear-shaped. Tractor stalls when more power required (load needle opened plenty) or just peters out for no apparent reason.

this makes me think carb right? all fettled, except I haven"t bought the set of drill bits yet, but: new gaskets; float height set right; good steady flow of good gas from tank/bowl (gas only mine)...

THEN she won"t restart, crank for ages. try choke in and out; check spark, looks OK. pretty sure timing is right, have advanced and retarded mag... bit of white smoke when cranking. but no firing. Check plugs next, slightly sooty/black. no sign of excess fuel in cylinders - maybe not enough gas in bowl?? set it to 3/8 from top as manual suggests...

frustrated!

Any thoughts appreciated - Mark P

 

[Greenday]

white smoke could indicate coolant in the cylinders

 

[Mark-Ia]

slightly sooty/back is a sign of excess fuel being burnt. Probably not warmed up before idle. replace the plugs.

 

[wilamayb]

Sounds to me like you are losing fire. Often coils and condensors will act in such a way. You should Check for fire next time it quits and wont start back.

 

[rick deere]

agree

 

[GaryinKs]

Magneto or Dist?

 

[Mark Pengelly]

Dear All,
THANKS so much for your prompt and helpful replies. Excuse the timelag in my reply - I'm UK based, just got up!

To respond to your replies:

My 1950 A has a Mag - although I have always suspected that it would have originally had dizzy/coil perhaps? (SN 649004) It also has a generator, not an alt.

When it stops working, first thing I did was check spark plug was still sparking. looks OK, although not a massive spark? How big should it be?! Nice spark across the points.

The tractor was totally restored 18 months ago, and I have probably run it 8 or 10 times since. always started up OK, and some of those times I've just quickly loaded it onto the trailor to take to a show, so it's only now I'm trying to do a bit more with it that the longer term running issues are showing I think.

I always had the feel there was too much fuel going in, sometimes it would run out the petcock valves etc after not starting - BUT none of that at present??

I bought new spark plugs from Deerly Departed for the restore - Autolite 386's. OK? Will try some different one's tomorrow. I also fitted new spark plugs leads.

Not sure it's firing evenly on both cylinders ALL the time?? That'd most like be a timing/mag issue right?

Don't think there's coolant in the cylinders, but will check...

Shall be working on the old girl again tomorrow... so more to follow. Maybe a video would help?

 

[bmiller36]

put a new condenser in and your problem will more than likly be solved. Doesnt cost much either so it wwont hurt to try one .Bob

 

[M-MAN]

Hook up a timing light and watch the flash. That's the easiest way to tell whether it's spark or fuel related when it dies.

 

[CLW]

Condenser would be my first guess also. Also try leaving the fuel cap loose. It could be a vent problem with the fuel cap.

 

[730-LP]

If you have a mag,tractor needs spark plug wires with WIRE not resister type wires,as others have said hook up a timing light and watch it as the tractor gets hot and see if the light gets weaker or goes out,my bet is coil or condenser.post back and let us know what the problem was.

 

[DRCA]

just went thru this with my GM, tried new condensor--no change. Bought new/rebuilt Magneto and all is good now. My mag sat unused for years before it failed me, like yours after 8-10 runs.

 

[Mark Pengelly]

Thanks all for your encouragement. Update: OK so I"m pinning my hopes on the new condenser. not easy getting these Wico parts this side of the pond(!), but found a v helpful guy from the (beautiful) county of Devon (my home) who has condenser, points and rotor cap all in stock. Sadly didn't arrive this morning in the post. Hopefully tomorrow (I have a show next Monday!)

In the meantime I have been checking the timing. Found that I haven"t enough adjustment on the rotation of the mag to get it to "click" when the fly is aligned to the LH Impulse mark. SO I"ve moved the governor gear one tooth clockwise so that the drive lugs of the mag are horizontal as they should be (right?). Q. Is it OK to do this?? Before I moved that gear the registration "V"s" were aligned; to get horizontal mag lugs I"ve had to move a tooth. OK to do this? Why do I need to do this?, pretty sure they were originally aligned with the Vs? Better check that I put on the flywheel right, eh? If that was off a notch on the crank the governor crank timing would be off also - relative to tdc - right?

I carry on learning. As I"ve read in other posts it is important to remove the mag before trying to replace the cover plate of the governor shaft other side. If you don"t you can press on the mag with the lugs mis-aligned and break the ear off the mount on the bottom! Note that I didn"t break mine, but a previous owner did; upon removal of mine (for the first time ever) I found that the dodgy looking soldering repair on the bottom lug was doing nothing. Also discovered the nut on the mag back had fallen off. So where to get a Wico XH-1042 body/housing in UK? No where! My Devon man pointed me to "Mark"s Magneto Services" in Minnesota. Excellent service. One phone call and a 2nd hand one is on the way, only $35 plus shipping... Let you good folks know how I go with the new condenser tomorrow.

 

[Mark Pengelly]

OK next update.

Points, rotor cap and condenser for the Wico XH-1042 arrived in post today. Good service from www.magneto.co.uk in the UK

all fitted along with some different spark plugs just for luck, NGK replaced the Autolite 386's. After quite a bit of cranking she started. I have the governor gear in it's original place ie with the timing mark with the cam gear lined up. As previously noted I don't think this is the perfect alignment, as the mag lugs are not totally horizontal, but friends says it should be near enough...

Anyway spluttered into life and adjustment of the load needle got it running fairly well, after five minutes spluttered and died. checked fuel running out the bowl, just a dribble and then nothing. AHA moment. eased off fuel cap and voila, running again. Fuel cap not breathing. presumably it should???

thought I'd really bottomed the not running after a few minutes issue with the above, but another 10 minutes running, sputters and dies AGAIN, tricky to get running again and then dies as soon as try to move off, ie no power. back to square one.

Should I try a new nozzle in the carb perhaps?