Farmall Super A

Recently replaced the head gasket and after putting everything back together the tractor was extremely hard to start and is running extremely bad. Could it be a timing issue?

Your likely to have the firing order wrong. 1,3,4,2 is the correct firing order with #1 being the cylinder by the radiator

I made sure that the plug wires were put back in correct order.

make sure the valves are set correctly. if it ran good before cant be timing as you dont touch timing removing the head. so i would say valve problem, or did you even set them? and the valves should have been removed from head and inspected as it might of been due for a valve job. and it should have had a compression check before taking apart also.

Valves looked ok when we removed them. Did not set them when we put it back together. Can you give me some guidance on setting the valves?

Unless the distributor was turned or removed, it shouldn't be out of time. Maybe the plug wires crossed?

Check the point gap. Check the plug gap. Check for a blue hot spark at each plug. It should be able to jump 1/4" to ground at each wire. At the plug end, not just at the distributor cap. Is the under side of the cap dry?

When the head was installed, was the valve lash set? Now that it has been run, might check them again. Sometimes they change after the initial start up. If the head bolts were not retorqued, do that first.

Check for vacuum leaks, especially around the manifold gasket. The design of the intake/exhaust manifold makes it possible for the exhaust to burn through to the intake causing exhaust to enter the intake. It happens, but save that for last as the manifold has to come off to be tested.

How is the carb doing? Gas clean? No flooding? Gas getting to the carb bowl? Take a sample from the carb bowl drain plug. It should flow a continuous stream with the fuel valve open, not slow to a drip or stop flowing. Look at what was caught. If there is water or trash the tank is contaminated and will need to be cleaned.

That's likely the problem, the valves need adjusting.

Before adjusting them, retoeque the head bolts.

They are supposed to be set hot, but that is near impossible to do before it cools off.

The hot setting is .014", so setting them .016" cold will be close enough.

You will need a feeler gauge. Remove the plugs so the engine will be easy to turn. Start at the front, turn the engine until the first valve goes closed. Put the feeler gauge between the valve stem and the rocker. Adjust the lash until the feeler gauge just drags but is not tight. Keep turning the engine until you find the loosest point. You will have to turn it through a few times to find it, but that is the best method. Once you find the loosest point,lock down the adjustment, recheck the gap, go to the next one. It gets easier as you get the hang of it.

You also may have a valve or 2 that needs to be adjusted which should be done when you do a head gasket

well there is your problem. firing order is 1342. so you get #1 cyl on compression stroke at TDC and set those two valves as they will be loose and the running mate to that cyl is #4 cyl. and those will be tight. that is how you double check to make sure #1 is on compression. you can only set valves this way as the cyl. being adjusted needs to be on compression. after setting #1 cyl. you turn engine 1/2 turn and set #3 valves watching #2 cyl. making sure those valves are on the rock , or overlap, or just being tight. then do #4 then #2 the same way and your done. there is the simplified version also where you only turn the engine over twice. also valve adjustment is part of a major tune up and should be done regularly. as parts wear the clearances change, get the clearance to tight and the valve will burn. to loose and it also causes excessive wear on parts. soon as you retorque the head your clearances will decrease.

Just follow the pictures and torque values and clearance settings in your manual. If you lost the manual time to order one online and you will have it in 2-3 days.

(quoted from post at 14:13:16 10/08/20) I made sure that the plug wires were put back in correct order.

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So did I. I checked them. Several times.

In the end, I had 2 and 3 swapped. No idea how it got past seven separate inspections, but apparently I had such confidence in my work that I was completely blind to my mistake.