John Deere 1020 CBC to JDB Conversion

Ryans1780 · Apr 30, 2023

I have a 1969 1020 that had the injector pump fail. I lined up the two timing pins according to the tech manual before I pulled the CBC pump. The diesel shop that I use called me and said that they couldn t rebuild it. They said the only option was to convert it to a JDB pump. We ordered the kit with all the new lines and and the JDB pump with the adapter shaft.

I have put everything back together, and timed the JDB pump through the window, but the holes on the shaft of the new pump do not line up with the timing gear. I pulled the shaft out enough to rotate it 180 degrees and it still doesn t line up. I talked to the shop, and they said it doesn t make sense. The only thing I can think of is rotate my flywheel until the timing gear lines up with the pump shaft.

I m curious if anyone else has come across this problem and what they did to resolve it.

Muir hill 101 · Apr 30, 2023

Have you got the engine for sure on top dead
center number one ?

used red MN · May 1, 2023

MH, His engine should have been on compression of number one cylinder when he lined up the marks of the first pump he removed.
OP welcome to YT! I suggest you go to the recent post I have linked. There you will find a post by Dieseltech who has a pump repair business, email him through the site email at the bottom of his reply, you have to be logged in to see his email button. He will probably reply with his phone number to discuss you issue.
Recent YT post

Ryans1780 · May 1, 2023

MH, I haven t pulled the valve cover to confirm, but I assumed it was since I had that little timing pin on the CBC drop in and the flywheel pin hit the hole at the same time.

MN, thank you. I will email him and ask.

Thank you both for the reply.

Muir hill 101 · May 2, 2023

You are correct . But i wonder why its boy lining up now ?

Ryans1780 · Jun 16, 2023

Just an update. Pulled the valve cover and barred the engine a couple times to watch my valves work. After watching how the valves worked, I barred it until the exhaust valve on 1 cylinder was almost closed. I took the timing pin and stuck it in the hole, then I barred the engine until the pin pushed in. I took the JDB injector pump and the holes on the shaft lined up with the timing gear. Bolted it all up, bled the lines, and BOOM! Tractor runs like a top.

The spot where the timing pins drops in is in a different spot on the flywheel than the place it dropped in when I pulled the CBC pump. It s close to it, but actually a little before the spot I marked on the flywheel. I don t know if the broken shaft on the CBC threw it out of time or what. Any ideas?

John Deere 1020 CBC to JDB Conversion

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