Bad miss

[Hoedown]

My Mid 60's 530ck, 4 cyl gas was running fine and i was digging away when it developed a bad miss. I got the hoe up and the machine on level ground and it died. It is now very hard to start and will die if you try to throttle up. Blows black smoke out exaust. I have replaced all tune-up parts, plus the coil, and carb. Compression on all 4 cylinders are 110 to115. Don't know what to try next.
Someone said stuck valve? Don't know, I've never experienced anything with a stuck valve.
Any ideas would be helpful.
Thanks, Hoedown

 

[Brown David]

Black smoke means it is flooding.

Proceed to remedy that first.

If I understand you right, you replaced the carb? The float setting may be wrong or the needle valve may be stuck or have something preventing it from fully closing.

You have good compression so if a valve is stuck it would have to be stuck closed. I'm not sure of the rocker arm configuration on that engine but I expect all rockers share a common shaft.

An intake rocker may have jumped off the valve or pushrod resulting in a miss, an exhaust rocker off would probably cause backfires, popping through the carb, etc.

 

[Nedd]

My Mid 60's 530ck, 4 cyl gas was running fine and i was digging away when it developed a bad miss. I got the hoe up and the machine on level ground and it died. It is now very hard to start and will die if you try to throttle up. Blows black smoke out exaust. I have replaced all tune-up parts, plus the coil, and carb. Compression on all 4 cylinders are 110 to115. Don't know what to try next.
Someone said stuck valve? Don't know, I've never experienced anything with a stuck valve.
Any ideas would be helpful.
Thanks, Hoedown

Have you cleaned the air cleaner lately. Black smoke and dies on throttle up, sounds like not enough air. That’s where I would start.

 

[Brown David]

Have you cleaned the air cleaner lately. Black smoke and dies on throttle up, sounds like not enough air. That’s where I would start.

Good point.

 

[Hoedown]

It developed the miss while I was using it, then died shortly after that. Once I got it to start, it was blowing black smoke. Thought it might have fouled a plug, or cracked the cap, or the coil was crapping out, so I gave it a complete tune-up. That didn't help, so I replaced the carb thinking the float may have stuck, but that didn't help. Currently, the air cleaner is not hooked up and still a miss with black smoke. It will turn the plugs black in just a few minutes of idle.
I guess I should take the valve cover off and see what's going on under there?
Stumped, I am......Hoedown

 

[used red MN]

With the air cleaner unhooked did you restart with cleaned plugs? If you had the plugs fouled with black fuel soot they will not immediately clean themselves and start firing correctly just because you disconnected the possibly plugged air intake/cleaner. Bird or mouse nest in air intake system changed position and is blocking intake? I have never seen a valve give rich mixture symptoms, could be possible. Broken valve spring, maybe cam gear key is shearing putting cam timing off. Never saw rich mixture symptoms due to that either. I also wonder if the “new carb” is not adding a problem? Still have the old one? If gas does not run out of it after a couple minutes with the gas turned on there is probably nothing wrong with it. Can’t say the same for a replacement carb. Just to add, really “left fielding” here but the oil isn’t way overfull, due to water/coolant intrusion?

 

[Hoedown]

I have cleaned the plugs several times and replaced the plugs, points, condenser, cap and button twice, along with a new coil with no charge in how it was running. The next thing was the carb and there was no difference between the old and new carb. Keep guessing. We'll figure it out.
Thanks, Hoedown

 

[used red MN]

I don’t think you are understanding exactly what I am asking. So rewording, by your recount of what you did it seems it is possible that you did the items to the ignition and spark plugs first. Then moved on to the fuel (carb) not returning to assess the condition of the spark plugs in any way. Say lack of available air to the carb (plugging of intake or air filter) was a contributing factor. You now have the carb air inlet open and are attempting to diagnose if this helps how the engine runs. However, the plugs are still fouled from running with a rich mixture which causes them to misfire. You start it but the engine does not purr like normal before all this started. You immediately say no that did not fix it. However, there is no way to know if it helped or not because you are still running it on the fouled plugs. Capeesh?

 

[Hoedown]

Yes, I understand where you are coming from, and yes I have cleaned the plugs before and after I changed the coil, and after I replaced the carb, and after I rechecked the points, and after I replaced the condenser, then replaced the plugs and did it all over again with no change in how it is running.

Sorry, just venting………breathe………

To me the spark looks weak at the plugs. That’s one of the reasons I changed the coil. Even with a new coil the spark still looks weak. Is there anything that would cut the spark down even with a new coil?

Still stumped............Hoedown

 

[Fixingfarmer]

Generally a week spark is still a spark and once it’s warmed up it shouldn’t still be missing. I’m assuming wires were done? A quick check to make sure they are all in the right place on the distributor cap. Rotor inside doesn’t have excessive wiggle. Then yeah look up top at rockers. Have you isolated which cylinder it is? That can help speed the process up? And can you? Some things can’t be isolated that can tell you something too

 

[rustred]

My Mid 60's 530ck, 4 cyl gas was running fine and i was digging away when it developed a bad miss. I got the hoe up and the machine on level ground and it died. It is now very hard to start and will die if you try to throttle up. Blows black smoke out exaust. I have replaced all tune-up parts, plus the coil, and carb. Compression on all 4 cylinders are 110 to115. Don't know what to try next.
Someone said stuck valve? Don't know, I've never experienced anything with a stuck valve.
Any ideas would be helpful.
Thanks, Hoedown

obviously, its flooding by blowing black smoke. so that means its choking itself to death. check the air cleaner for being frozen with ice., it should have an oil bath air cleaner. I am reply to what i am reading... black smoke is a flooding engine. nothing to do with electric side., even a stuck valve is a dead miss and dont make it blow black smoke. when it starts shut the fuel supply off to the carb and if itis flooding it will clear itself out as it uses the gas up in the carb... then u know the rest of the story.

 

[Fixingfarmer]

He says the air cleaner is not attached. Carb or actual miss at this point

 

[nick831]

Maybe one idea, an old mechanic told me years ago that spark acts like fuel and fuel acts like spark. I know it doesn't sound right but I have seen it a few times in my career. Do you have 12 volts to the positive side of the coil? How about the wire from the negative side of the coil to distributor, in good shape? Is point gap set properly? Does distributor shaft have excessive play? A few things to consider. I am focusing more on electrical as you replaced the carburetor and put the old one back on the tractor with no change. Air filter is off and not in play. Compression is good. Look at the areas I outlined above. You might find the problem. Best of luck. Nick

 

[rustred]

Yes, I understand where you are coming from, and yes I have cleaned the plugs before and after I changed the coil, and after I replaced the carb, and after I rechecked the points, and after I replaced the condenser, then replaced the plugs and did it all over again with no change in how it is running.

Sorry, just venting………breathe………

To me the spark looks weak at the plugs. That’s one of the reasons I changed the coil. Even with a new coil the spark still looks weak. Is there anything that would cut the spark down even with a new coil?

Still stumped............Hoedown

well well , so you have not tryed new spark plugs. i just went through this same thing on my honda quad. i dont know why but the plug only lasts so long then it wont fire any more. with only a faint spark on it. put a new one in and first rank its running. so it might be a good idea to try some new plugs. or at least if its running pull out each wire from the dist. and see which one is the culprit. once plugs get fouled thy will not fire properly. and yes i cleaned mine but it was no change. so something to stew over.