Ford 861 hard start, bad run

Ford45

New User
I'm working on a ford 861 that has set for 20 years. I've replaced the fuel tank and line with new ones, cleaned the carb and put in a carb kit. Replaced the coil, distributor cap and bug, points and condenser, and the plug wires. I've checked the static ignition timing. I've adjusted the valves with the engine running according to the book. I've replaced the manifold gaskets. I have not checked the compression but when the tractor is cranked it acts like there is a lot. The engine doesn't have many hours on it. It is still a 6 volt positive ground.

Ok now the problem, the tractor is horrible to start, even when pulled and could also run better. Once started it has descent power and will idle smoothly as low as 300 (I have it set at 550). If the throttle is opened to fast it will die or drop to two cylinders. The same thing happens if two big a load is put on it. When it starts it often starts on two cylinders. I can adjust the carb until it sounds lean or spits out black smoke or anywhere in between and the same thing happens. The spark will jump a 1/4 inch gap but is yellow. I have never worked on a 6 volt tractor before but it cranks slower than other engines I've worked with. It also seems to use a lot of fuel for an engine of its size.

This tractor has been in the family for almost its entire life and has never started good,Is that just the nature of a 861? Its sibling a 641 has always started almost instantly.
 
Welcome to the forums. Nope, that's not normal.
Without a compression test or leak down test, my off
the cuff guess would be sticky valves from setting.

You could soak the cylinders in ATF for a few days and/or
add some to the gas and work it to see if that helps it out.

That doesn't explain yellow spark. Wouldn't hurt to clean
and re-gap the points. I like to clean them with contact
cleaner to make sure there was no oil on my gap gauge.

The 8x1 series will use more gas than a 6xx or even a 8/9x0.
Larger intake and carb than on the 8x0, larger engine than the 6xx.
 
What plugs do you have?? I now use NGK 3112 in my ford and they seem to help a whole lot
 
What did you use for a replacement coil? If you used a 12V coil on a 6V tractor that may explain the weak spark.

It is also not out of the realm of possibility that the new ignition parts are bad. They are manufactured overseas and not the best quality parts these days.
 
Let us get back to basics.
An engine needs THREE things to run.
1) Compression

2( A proper fuel and air mixture.

3) A properly timed spark.

Since you already have noted a problem with the spark, that would be the place to begin troubleshooting.
You need a good strong spark in order for the engine to run right. A weak yellow spark simply will not do. You need a decent blue spark to run properly.
Check for the correct ignition coil. Check the points for proper alignment, clean contacts, and resistance. Check the condenser. Any of these items can cause weak spark.
Until you get a good spark, you are wasting your time to try to find the problem elsewhere.
A general rule of thumb in fixing any problem is to repair the KNOWN problems FIRST.
Changing plugs or checking distributor advance is pointless without a good spark.

Also, it is not normal to idle the engine down to 300 RPM. Stick with the manufacturer's recommended idle speed.
 
First make sure you have the plugs in the correct firing order. Sounds to me like 2&3 may be crossed.

Rick
 
Thanks for the ideas, I'm going to check into several of them this weekend. my best guess is an ignition problem, but I'll check the compression.

for the coil since the tractor is positive ground should the + go to the distributor?

About the valves, before the engine was started I inspected them through the spark plug holes and what I could see of the seating surfaces was very good. Later I followed the instructions in the book and adjusted the valves with the engine running. I am very confident that at lower speeds the valves are not sicking. The book implies that valves that work at idle can still stick at higher speeds and or under heavy loads, which is when the this engine gives problems. Has anyone ever experienced this, and how can it be diagnosed?
 
Thanks to everyone. Problem solved, the tractor starts almost instantly now. The old coil was wired up backwards, and when I had replaced it I put the new on on the same way. Switching The wires made The tractor start (and run under a load) better than it ever has. This tractor has had a reputation of being hard to start for the last 40 years because of a simple wiring error.

For other people with the same problem, the coil wired up backwards would still throw a 1/4 inch yellow spark. A test light placed between the distributor and any plug would also light up during cranking. I think running the tractor with the coil hooked up wrong damaged the coil. When I hooked it up right it the spark was still yellow, but the tractor ran great. Switching to another new coil made the spark blue. The tractor is 6 volt positive ground, when it ran badly I had the negative post going to the distributor, switching the wires so the positive post goes to the distributor made the tractor run great.

Thanks again for the help, you saved a lot of headache.
 

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