jd 420 oil pump timeing

[kwrules]

trying to put the engine back together/ and my manual says you need to time the oil pump it does not say how to do it. cant find anything on youtube any help or info would be appreciated. ( i bought this tractor and the engine was already apart)

 

[wore out]

(quoted from post at 19:18:36 05/04/21) trying to put the engine back together/ and my manual says you need to time the oil pump it does not say how to do it. cant find anything on youtube any help or info would be appreciated. ( i bought this tractor and the engine was already apart)

The reason for timing the oil pump on these GAS engines is that the distributor is driven by an offset "tang" and "slot" system on the oil pump gear and distributor shaft and if all is done as it was originally the distributor housing "clock position" and the exact location of the spark plug wires in the distributor cap will be in the same position as it all was when it left Dubuque.

You must have a "best used as a doorstop" shop manual if it doesn't explain in detail as to the position the oil pump shaft needs to be in as it's assembled.

On the other hand, if you have a basic knowledge of how to time an engine it can be done no matter of how the oil pump gear was "timed" (or not).

When they stretched that block out to four cylinders and made a diesel version the exact timing f the oil pump gear became imperative, but not with what you are working on.

 

[M-MAN]

No idea where you are in your assembly process so I'll try to give you an idea. First off you should retire the manual you have to it's proper flyswatter status and get a real Deere manual on eBay or from Deere.

In a nutshell you need the front ( 1 ) cylinder at the top of its compression stroke. You should see TC or DC in the center of the timing window on the flywheel. You will then mesh the pump gear with the distributor drive gear with the slot in the distributor drive pointing exactly front to rear and the narrow part of the tang on the outside.

Should you happen to have the engine at the top of the exhaust stroke the distributor will be 180 degrees off when you try to set it in. Not a big deal as you can correct it by driving the pin out of the distributor drive and turn it half a round and put the pin back in.

 

[MikeinKy]

The first reply was correct, with the exception of one thing. The slot doesn't go exactly front to rear. It goes about 15 degrees
clockwise which is about one tooth. I have the John Deere service manual and it tells you to use a special tool in the slot and
line the tool straight with the block. The tool isn't available, I don't think. An old deere mechanic told me how to do it. Make
sure the narrow side is out. there is only about .060 difference in the width of the two sides. I use a caliper and measure them
and mark the narrow one with a marker or chalk.

 

[Gene Davis (Ga.)]

These engines will run on one cylinder only when the oil pump is not timed correctly in them. I found that out the hard way.