'52 Allis WD - Bark, pop, bang!

I recently picked up an old Allis WD, and I have been working on restoring it for the last few weeks.  It’s been sitting outside for a long time, but I managed to get it running.  So I replaced some seals and gaskets and gave it a full coat of paint.  Some of it I couldn’t have done without the wealth of knowledge on this board, so thanks for that.  This is my first post however, as I am running out of ideas with my troubleshooting. 

I will try and provide as much detail as I can...

I only got the tractor about a month ago.  I had it up and running like a watch.  Spent a few hours mowing pasture, commuting around the farm, not a hiccup. I am pretty confident I can rule out any mechanical issues, valves, compression, etc based on how perfect it ran, and the power was excellent.  

Then one morning after a big dumping of snow, I went out to do some snow moving with it.  I had driven it the day before, but now it sounded louder than it should, kinda barky.  When I increased the RPM, it would occasionally backfire out the exhaust, seemed to be running lean.  After checking over the carb 10 times over, I eventually found my points were worn down to nothing on the cam heel piece. 

 Installed new points, condenser, 12v coil,  ignition wires, spark plugs, and set valve lash and it was no better.  Timing set with a light.   It would run perfectly for 20 minutes, and then back to popping and barking.  Though idle is perfect.  Also bypassed the ignition switch and ran power right to coil.  I removed the whole distributor and found it to be nearly seized.  I soaked in in diesel overnight and got it all cleaned up and the timing advance working again, which was stuck at full advance (where I set it with a light).  I thought for sure this would solve my issues, but it didn’t  make anything better.  In fact it’s almost worse. 

The engine will start in about half a second, idles great, but will not let me raise throttle without fire out the stack, and horrible popping and barking. 

I did notice there is some side to side play in the distributor.  The bushing is clearly worn.  Maybe worse than it was after cleaning out all the crud.  With just my fingers pushing, I measured 15 thou of play from one side to the other.  Over 20 thou if I use a screw driver to torque it.  I plan to install a new bushing, so I tried staking the bushing a bit to tighten the tolerance.  No improvement.  I want to think this is the cause, but I have a Ford 600 that has far more wobble to it and it runs great. 

Also when I put the timing light on any given spark plug, they are all firing, but each plug will randomly skip a few beats and then start up again.  I think this has to be electrical issue.  I will probably start by getting another set of points, just in case these are duds. 

I would appreciate any thoughts.  Especially around the distributor play.  I know it’s not ideal, but don’t think it could make it this bad. 

Thanks all. 

Cheers.

I have added fresh fuel to the tank about 3 times, as I have been working the tractor, and I have run the fuel from an auxiliary fuel tank with fresh fuel, just to rule out water in the tank.  I have perfect flow down to the carb, and if I remove the bowl drain, then it will continue to run fuel as fast as it can get through the float valve.

Sticking exhaust valve: I did adjust the valve lash, and ran the engine with the cover off.  Everything seemed to be in good shape, but that doesn’t mean a valve can’t be hanging up intermittently.  Hopefully I didn’t burn an exhaust valve, I don’t really want to pull the head.  The only reason I don’t think it’s a valve, is because it did seem to be intermittent at first, and I can see the spark dropping out when clipping the timing light to any of the ignition wires. 

I have two condensers, one of which is brand new.  Both seem to run the same.  It’s possible they are both junk, but unlikely?  I agree with the comments on the points though, they seem to be poor quality.  The heel has already worn off half way and they kept losing their gap.   But I suspect this may be accelerated by a worn bushing.    

I do not have any resister on the coil, since I installed a 12v coil, and am running a 12v battery. 

There is no soot on the engine.  It’s a freshly painted orange tractor, and there is no sign of any exhaust blowing out from the manifold gasket.  I don’t think it could be a manifold leak, because in my experience, a manifold leak will run okay at higher RPM, but won’t idle.  Mine seems to be the opposite. 

I can really hear a difference in the tone of the engine when I play with the timing as well.  At idle, it will smooth out when I advance it too far.  And it gets louder and barkier the more I retard the timing.  My dad thought my muffler baffles were rotted out, but when it’s running properly, it’s much quieter. 

Hoping my dad will be able to grab me a set of points from his parts bin this week, and I will try that.  Also need to look into getting a new distributor bushing, or a replacement distributor.  Until then, I’m going to try another compression check, just in case a valve is hanging open or burned, that might tell me something.      

I appreciate all the ideas.  I’ll post back when I figure out something… good or bad…

Thanks so much.