Author Topic: Advice needed on Ball and spring in crankcase 1956 A7  (Read 437 times)

Offline bikerbob

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I have had to strip the engine in order to replace timing side bush whilst I had it stripped I decided to renew the ball and spring next to the bush. I have bought a new ball and spring but the new spring is not the same as the old one as can be seen in the photo attached it is made of thicker wire and is a lot stronger than the original. My question is should I use the new spring and ball or should I keep the old spring and just use the new ball. The new spring is on the right. The  supplier of these parts is MCA for obvious reasons I need to get this right as I don't want to strip the engine down again and could the new spring cause any problems. Thankyou.





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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #1 on: 30.06. 2018 15:36 »
I just changed the spring and ball on my Plungie. The new spring was lighter than the old one!

Offline Wayno

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #2 on: 30.06. 2018 20:24 »
From my experience this ball and spring allow pressurized oil from the pump through to the main crank journal and from there onto the big ends.
Also if the ball is given a sharp tap against its seat to create a good fit, the pressure of the spring on the ball will prevent the engine wet sumping.
The spring pressure needed on mine to allow oil through is very light.  I know as the engine is stripped down at the moment.
But I can leave the engine a full year and she does not wet sump.
I think this ball valve is mainly there to stop the wet sumping but must not be too strong to reduce oil feed to the main crank journal.
If your engine has not wet sumped before then I would stick with the original spring.

Hope that helps
Wayno 

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #3 on: 30.06. 2018 21:37 »
G'day Bob.
That new spring looks like an oil pressure relief valve spring. It should be a very light spring. See pic.
Cheers
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Offline bikerbob

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #4 on: 01.07. 2018 10:45 »
Thanks for those replies I have ordered another ball and spring from a different supplier on ebay and they show a picture of the spring and it is the same as the original. The supplier of the stronger spring is MCA who I believe are based in Birmingham, over the last 20 years or so I have had some issues with the quality of some parts supplied by MCA and I try to avoid them but in this case it was not until the ball and spring arrived  that I realised it was from MCA it was sealed in their plastic bag with the MCA logo on the front.

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #5 on: 01.07. 2018 19:38 »
Could be a misunderstanding over pressure relief valve and anti-wet sumping valve.

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #6 on: 01.07. 2018 21:25 »

 I think it looks like an A65 spring; I bought one for possible future use as a 'mod.' Thought I took a pic of it the other week when someone else was aking about them.....I'll have a look when I have some downtime (had an early morning call *work*)
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Offline Peter Gee

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #7 on: 05.07. 2018 19:42 »
You have an A65 type pring..the original is very fine  coiled and light as your picture shows...now if you had a SRM new pump, probably the stronger one would be fine and, as long as to "tap" it in, give you a strong anti- wet sump ability.

However  far worse than wet-sumping is big end oil starvation due to too much poundage on the spring. You can but a good anti wet sump valve that screws in the crankcase for 35 pounds.... engine lower end rebuild not so cheap.

Hope this helps...err on the side of caution.

Online chaterlea25

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #8 on: 05.07. 2018 20:59 »
Hi All,
Quote
err on the side of caution.

In that case do NOT fit an ASV valve  *warn*
More engines have failed because of them than most other reasons

When the oil leaks away from the pump side of the ASV the pump will not prime itself

My 2 cents worth is to modify the original ball and spring to the A65 setup where the ball sits against the back of the pump!!
Lots of posts on this before
A pump would have to be completely knackered not to lift the photo'd springs
Remember the oil pump pressure will compress the strong spring in the pressure relief valve  *ex*

John
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1963 RGS (ongoing)

Offline kiwipom

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #9 on: 05.07. 2018 21:39 »
hi guys, to remove this ball and spring i would have to grind some of the pump side bush away!!! you will notice that at some time this engine has had a wee bit of trouble staying together, cheers
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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #10 on: 05.07. 2018 22:07 »

 
Quote
I think it looks like an A65 spring; I bought one for possible future use as a 'mod.' Thought I took a pic of it the other week when someone else was aking about them.....I'll have a look when I have some downtime (had an early morning call *work*)

 I couldn't find the pics I took so did another- then found the first anyway...stuck them in the Beeza folder, hey *bash*

 Heavier looking spring is the A65 one,  and is different to Bob's heavy one, so I think that can discount it being one of them  *dunno*


 
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online chaterlea25

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Re: Advice needed on Ball and spring in crankcase 1956 A7
« Reply #11 on: 05.07. 2018 22:38 »
Hi All,

SRM list the same spring for A10 and A65
Which is the fine wound one

http://www.shop.srmclassicbikes.com/product-category/bottom-end-and-timing-covers?page=7

John
1961 Super Rocket
1963 RGS (ongoing)