8N Oil Pump

[coltony]

I'm currently in the process of rebuilding the engine of my grandpas 1952 8N, but I have a few questions on the oil pump. during my oil pump rebuild I replaced the bushing and got the tool kit to ream the new one out. while working on the bushing I noticed the guide was slightly of center from the bushing and there was no way to center it correctly in the hole, the jig only fit one way and it was a tight fit to get the screws through to mount the jig. I proceeded to ream out the bushing with my tool kit but the attached photo is the end result.

is it normal for the jig to be this off center? I'm a little worried about the wall thickness of the bushing on the one side as it is literally paper thin. there doesn't seem to be a ton of play in the shaft I'm just concerned about wall thickness mostly.

 

[Jim in LA]

I had mine rebuilt at machine shop last spring. They had the jig, took two attempts, messed up the bushing on the first one and I think It was because it was of center.

 

[TheOldHokie]

(quoted from post at 18:00:26 05/01/23) I'm currently in the process of rebuilding the engine of my grandpas 1952 8N, but I have a few questions on the oil pump. during my oil pump rebuild I replaced the bushing and got the tool kit to ream the new one out. while working on the bushing I noticed the guide was slightly of center from the bushing and there was no way to center it correctly in the hole, the jig only fit one way and it was a tight fit to get the screws through to mount the jig. I proceeded to ream out the bushing with my tool kit but the attached photo is the end result.

is it normal for the jig to be this off center? I'm a little worried about the wall thickness of the bushing on the one side as it is literally paper thin. there doesn't seem to be a ton of play in the shaft I'm just concerned about wall thickness mostly.

Off center is no good. The issue is not wall thickness. If the reamed bore is off center the gears will bind on each other and/or the walls of the housing.

Your jig should have come with a centering pilot. You put the pilot in the housing bore and use it to center the jig on the housing before tightening the attaching bolts. Then you withdraw the pilot, install a new bushing in its place, and ream the bore in the bushing.

If the jig wont center its worthless.

TOH

 

[coltony]

(quoted from post at 19:19:34 05/01/23)

(quoted from post at 18:00:26 05/01/23) I'm currently in the process of rebuilding the engine of my grandpas 1952 8N, but I have a few questions on the oil pump. during my oil pump rebuild I replaced the bushing and got the tool kit to ream the new one out. while working on the bushing I noticed the guide was slightly of center from the bushing and there was no way to center it correctly in the hole, the jig only fit one way and it was a tight fit to get the screws through to mount the jig. I proceeded to ream out the bushing with my tool kit but the attached photo is the end result.

is it normal for the jig to be this off center? I'm a little worried about the wall thickness of the bushing on the one side as it is literally paper thin. there doesn't seem to be a ton of play in the shaft I'm just concerned about wall thickness mostly.

Off center is no good. The issue is not wall thickness. If the reamed bore is off center the gears will bind on each other and/or the walls of the housing.

Your jig should have come with a centering pilot. You put the pilot in the housing bore and use it to center the jig on the housing before tightening the attaching bolts. Then you withdraw the pilot, install a new bushing in its place, and ream the bore in the bushing.

If the jig wont center its worthless.

TOH

thank you for both of the replies. That's kind of what I thought and I'm going to get a new bushing and re do it. hopefully I can get it straight this time....

 

[lha]

I took mine to an older man [about 10 years older than me,at 70] that has a tractor shop in the Town about 15 miles away. He took
my Tisco that I had for about 10 years and stated that the driven gear wasn't right,but he got one from his collectionand got it
right.These old coots are a rare breed.

 

[TheOldHokie]

(quoted from post at 12:48:55 05/02/23)

(quoted from post at 19:19:34 05/01/23)

(quoted from post at 18:00:26 05/01/23) I'm currently in the process of rebuilding the engine of my grandpas 1952 8N, but I have a few questions on the oil pump. during my oil pump rebuild I replaced the bushing and got the tool kit to ream the new one out. while working on the bushing I noticed the guide was slightly of center from the bushing and there was no way to center it correctly in the hole, the jig only fit one way and it was a tight fit to get the screws through to mount the jig. I proceeded to ream out the bushing with my tool kit but the attached photo is the end result.

is it normal for the jig to be this off center? I'm a little worried about the wall thickness of the bushing on the one side as it is literally paper thin. there doesn't seem to be a ton of play in the shaft I'm just concerned about wall thickness mostly.

Off center is no good. The issue is not wall thickness. If the reamed bore is off center the gears will bind on each other and/or the walls of the housing.

Your jig should have come with a centering pilot. You put the pilot in the housing bore and use it to center the jig on the housing before tightening the attaching bolts. Then you withdraw the pilot, install a new bushing in its place, and ream the bore in the bushing.

If the jig wont center its worthless.

TOH

The bolt holes on the jig are not for alignment. They are for clamping the jig in place once its centered using the pilot tool. If they are interfering with alignment just drill them oot to a larger size.

TOH

This post was edited by TheOldHokie on 05/02/2023 at 12:55 pm.