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A7 & A10 Engine
A7 1946-1950
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The BSA A7-A10 Forum
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Technical (Descriptive Topic Titles - Stay on Topic)
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A7 & A10 Engine
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Oil feed to Rocker box
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Topic: Oil feed to Rocker box (Read 356 times)
Gavin
Valued Contributor
Join Date: Oct 2006
Posts: 283
Karma: 5
Oil feed to Rocker box
«
on:
04.07. 2022 20:01 »
Just a random question I'm pondering:
There are 2 different sized holes in the bolt through which oil passes as it's fed to the rocker box. (65-306) How does one know if the engine requires the larger or smaller holed bolt? As far as i can see neither Roy Bacon or Haynes covers this wonderful detail. obviously there have been changes to the rocker box oil feed over the years. Any insights would be appreciated. thanks.
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Mandurah Australia
Brian
Wise & Enlightened
Join Date: May 2007
Posts: 1806
Karma: 43
Mt Gambier, South Australia.
Re: Oil feed to Rocker box
«
Reply #1 on:
04.07. 2022 22:11 »
These bolts come with two different size holes, the small holes are oil feed to the rockers of the A10/7 series and the ones with large holes are oil drain bolts for the B33/31 series.
In the attached pic you can see a pipe running from the rear of the cylinder head down in front of the magneto, that pipe attaches to the crankcase and lets the oil in the cylinder head drain back down. The bolts with the large holes are used on both ends of this pipe.
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Peter in Aus
Valued Contributor
Join Date: Feb 2014
Posts: 430
Karma: 2
South West, West Australia
Re: Oil feed to Rocker box
«
Reply #2 on:
05.07. 2022 01:42 »
Hi Gavan, use the ones with the small holes that gives more than enough oil up top, from memory they are about 1/16" holes, quite small any rate, some where in the forum there is a bit about them.
See you at Kal.
Peter
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Busselton West Australia
49 A7 longstroke
58 A10 SA
RichardL
Outside Chicago, IL
Wise & Enlightened
Join Date: Nov 2007
Posts: 6387
Karma: 55
Re: Oil feed to Rocker box
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Reply #3 on:
05.07. 2022 02:15 »
I believe this post from dpaddock (what happened to him?) may be the definitive answer regarding rocker feed holes:
https://www.a7a10.net/forum/index.php?topic=592.msg3432#msg3432
Also, if you choose, you can read my meanderings from 2008 leading up to learning this answer.
Richard L.
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Colsbeeza
Resident Legend
Join Date: Aug 2015
Posts: 690
Karma: 5
Re: Oil feed to Rocker box
«
Reply #4 on:
05.07. 2022 04:17 »
More here too Gavin.
https://www.a7a10.net/forum/index.php?topic=17105.0
My measurements verify that the standard size is 3/64".
Col
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1961 Golden Flash
Australia
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Oil feed to Rocker box