B25 oil pump drive spacer

Here you can talk about all kind of TECH for the B50 B44 B25 And Other BSA unit Singles

Moderator: minetymenace

Post Reply
User avatar
madsundaysurvivor
>80
>80
Posts: 94
Joined: Fri Mar 27, 2015 11:28 am
Location: Valencia (Spain)
Has thanked: 12 times
Been thanked: 4 times
Flag: Spain
Contact:

B25 oil pump drive spacer

Post by madsundaysurvivor » Sun Jan 20, 2019 9:59 pm

I'm a Little confused with this part and need some help
when I got my engines (BSA's B25 1968) they were completely disassembled and some parts were missing
In parts manual of 1971 this part appears as 71-2291 (number 57):
bsa b25 1971.JPG
But in 1968 parts manual don't appear:
bsa b25 1968.JPG
In my crank the pump drive occupies all the space and don't gap for the spacer, and the out diamerter of the drive is the same of the crank arm, then te spacer will not hold anything and I do not understand what it is for
20190119_174509[1].jpg
Then when I put the crank pinion the nut doesn't hold the crank to the ball bearing, I'm right??

User avatar
kommando
>1400
>1400
Posts: 1774
Joined: Mon May 24, 2004 8:41 pm
Location: Scotland
Has thanked: 0
Been thanked: 18 times
Flag: Ireland

Re: B25 oil pump drive spacer

Post by kommando » Sun Jan 20, 2019 10:37 pm

When the crank had 2 ball bearing mains the crank was located on the driveside and the timing side floated, no spacer needed. Once a roller went on the driveside then the location of the crank moved to the timing side so the spacer was fitted. If you have fitted 2 ball bearing mains as per 68 stick with the 68 parts book. If you have fitted the roller main on the riverside then get and fit the spacer.
These users thanked the author kommando for the post (total 2):
minetymenace (Mon Jan 21, 2019 8:51 am) • madsundaysurvivor (Mon Jan 21, 2019 2:50 pm)
Rating: 66.67%

User avatar
JB
>420
>420
Posts: 438
Joined: Tue Jun 15, 2004 8:32 am
Location: Devon, England
Has thanked: 3 times
Been thanked: 3 times
Flag: England

Re: B25 oil pump drive spacer

Post by JB » Mon Jan 21, 2019 9:27 am

From memory if you change an early two ball bearing crank to a roller on the drive side you will need to machine the shoulder on the crankshaft on the timing side.

The earlier two ball bearing crankshaft was located on the driveside ball bearing. You have to machine the shoulder down that the timing side bearing fits onto so that it is shorter than the width of the bearing meaning that the bearing inner will be clamped to the crankshaft to locate it, you will also need the later spacer as mentioned.

The modification is fully detailed in Rupert Ratio's book.
These users thanked the author JB for the post:
madsundaysurvivor (Mon Jan 21, 2019 2:50 pm)
Rating: 33.33%

User avatar
madsundaysurvivor
>80
>80
Posts: 94
Joined: Fri Mar 27, 2015 11:28 am
Location: Valencia (Spain)
Has thanked: 12 times
Been thanked: 4 times
Flag: Spain
Contact:

Re: B25 oil pump drive spacer

Post by madsundaysurvivor » Mon Jan 21, 2019 2:47 pm

thank you for yours answers, Now I understand it. Then will not use spacer, I prefer two ball bearings, in engines not for Street, many times I use C4 poliamide cage.

Another doubt... Which is the correct float end axial slack of the camshaft axle? I can not find this data

I use a megacycle x4 cam and have more axial play that the OEM, and don't konw if use a shim washer to correct it

User avatar
kommando
>1400
>1400
Posts: 1774
Joined: Mon May 24, 2004 8:41 pm
Location: Scotland
Has thanked: 0
Been thanked: 18 times
Flag: Ireland

Re: B25 oil pump drive spacer

Post by kommando » Mon Jan 21, 2019 4:54 pm

Aim for 5 to 10 thou, if possible fit the shim behind the flange of the cam bush so it is not rubber against.

User avatar
madsundaysurvivor
>80
>80
Posts: 94
Joined: Fri Mar 27, 2015 11:28 am
Location: Valencia (Spain)
Has thanked: 12 times
Been thanked: 4 times
Flag: Spain
Contact:

Re: B25 oil pump drive spacer

Post by madsundaysurvivor » Mon Jan 21, 2019 9:47 pm

Thank you kommando

Ufff is late for this, the bushes are fit and grinded, I had not thought
Although I could start over
Do you see any problema if the shim is between the cam wheel and the Bush in the timmin cover?, of course always the cam lobers are aligned with the cam followers.

User avatar
kommando
>1400
>1400
Posts: 1774
Joined: Mon May 24, 2004 8:41 pm
Location: Scotland
Has thanked: 0
Been thanked: 18 times
Flag: Ireland

Re: B25 oil pump drive spacer

Post by kommando » Tue Jan 22, 2019 12:45 pm

Depends upon the thickness of the shim, 10 thou could rip up easily, 25 thou would be ok. A bodge is to tap one of the bushes in to take up the slack but it can always them move back in unless the gap is filled.

User avatar
madsundaysurvivor
>80
>80
Posts: 94
Joined: Fri Mar 27, 2015 11:28 am
Location: Valencia (Spain)
Has thanked: 12 times
Been thanked: 4 times
Flag: Spain
Contact:

Re: B25 oil pump drive spacer

Post by madsundaysurvivor » Wed Jan 23, 2019 6:26 pm

efectively if it is too much thin could be break. At the end I decided not risk in this episode. So I have made a new bush with the correct inner wall, to keep a clearance of 7 thou.
thanks for your tips,

Post Reply