JD 420 UPDATE

[grandpa Love]

Need a bit of help. New plugs and wires
today, fired right up. But, still back
firing through carb. Pulled valve cover,
found the issue. Cotter pin on front of
rocker arm assembly was broken, the
washer and spring were off and the
rocker arm was wedged out of place.
Front valve is stuck. Push rod was bent.
I straightened it 98 percent good. But
valve is stuck!! Finally pushed spring
down and removed keepers. The valve
spring in bent crooked and deformed.
Also the tube that the rocker arms ride
on is bent up a bit on the front. Anyone
have a 420 parts tractor that can sell
me a few parts??

 

[J Hamilton]

If nobody here has any, try 2 cylinder plus salvage. They should be able to help. 417 589 3337

 

[old]

If there still open. I have a card from them but it s a good 20 plus years old

 

[grandpa Love]

Thanks! I'm a Farmall cub and ford guy

 

[wingnuttx]

Kevin. Once you go green youll never go back to anything else. Its a hypnotizing experience. lol. Wingnut

 

[J Hamilton]

I haven't been ther in years, their website still shows they are

 

[J Hamilton]

You're welcome. I'm a die hard Case guy but I have a few friends that are JD guys. If 2 cyl plus can't help another place would be McGrew.

 

[old]

There south west of me about 35-40 miles

 

[J Hamilton]

I was thinking they were fairly close to you

 

[old]

Yes there at Conway MO which is just west of Lebanon Mo and Lebanon is around 25 miles from me

 

[Geo-TH,In]

If intake valve is stuck closed. Just leave it closed, remove rocker are, and make it a one cylinder if the 420 is a 2 cylinder. Might run cooler if you pulled the plug too.

That would be half of a Johnny popper, just a pop, no per.

Sounds like you may be pulling the head and get new a complete valve job.

Hope you have a good machine shop. All the old machine shops are gone in my hood.

 

[onefarmer]

You can try this place too. I drove by it while down in Indiana stopped in and they have a complete reconditioned head for my JD620 in stock. I got it and put it on that winter.
New Paris

 

[Steve@Advance]

If the valve is stuck so hard it can't be broken loose, the head will have to come off and the valve freed, possibly with a new valve and guide.

Replacing the broken and bent parts without freeing the valve will just break and bend the new parts, or worse.

Last thing you want is to have the damaged valve break off inside the cylinder!

 

[J Hamilton]

Lucky for me, I have a very good machine shop about 10 miles from me and they are always a month out for return. And double lucky for me, last year I was offered a very nice Souix valve and seat grinder with an extra box of parts and acc for it for $350 which I bought on the spot!

 

[grandpa Love]

Steve, problem is the valve will move down with just a light tap from a hammer. Very little room to get vice grips on it to try turning it. Also with the head on we can't tap it up.....grrrr. Off with it's head!! Done enough cubs, ford N tractors and a Farmall B. Just had hoped to get it running to sell for our friend. If it runs good enough our son will want to keep it. As will my dad!!

 

[Jim.ME]

(quoted from post at 08:26:24 10/17/21) Steve, problem is the valve will move down with just a light tap from a hammer. Very little room to get vice grips on it to try turning it. Also with the head on we can't tap it up.....grrrr. Off with it's head!! Done enough cubs, ford N tractors and a Farmall B. Just had hoped to get it running to sell for our friend. If it runs good enough our son will want to keep it. As will my dad!!

With the piston down, use a long length of small rope, like clothes line to feed in through the plughole. Once you get the cylinder filled up, carefully turn the engine to bring the piston up. The rope will compress some, should push the valve up, and hold it for you. You could work it up and down, Turn the engine to lower the piston a bit, tap down, turn engine for up, while applying penetrating solvent of your choosing.

 

[Geo-TH,In]

About 20 years ago I sold my antique valve grinder and seat grinder.
Regrets.

All the places in town that used to bore, turn cranks, turn cams, do head work, flatten heads or blocks are all out of business.

Goes to show engines today last longer that they used to or people just buy new instead of overhaul.

 

[MSD]

Try Tom. He has a pretty good selection of parts for these and is reasonably priced also. If you need to push the valve back up, try attaching an air hose to the spark plug hole. If the valve is not stuck it will push it back rip.

 

[formerly ny bill]

I had 2 exhaust valves on the Regular that would stick open, pop back up with a little lift from a pry bar, and then stick open again as soon as the rocker arm pushed it down. pulled the head and took out the valves. All that came out was a tiny grain of carbon, but that solved the problem.
Can't recall any 420 I have seen that didn't have a wide front axle. With the tricycle, I would try for a few extra bucks for your friend when you sell it.

 

[buickanddeere]

(quoted from post at 21:04:49 10/16/21) If intake valve is stuck closed. Just leave it closed, remove rocker are, and make it a one cylinder if the 420 is a 2 cylinder. Might run cooler if you pulled the plug too.

That would be half of a Johnny popper, just a pop, no per.

Sounds like you may be pulling the head and get new a complete valve job.

Hope you have a good machine shop. All the old machine shops are gone in my hood.

You can not be serious .