flywheel end main bearing question

[BAD942B]

A quick question, on the centre & timing case main bearings the 8mm oil drilling goes straight into the main 10mm transverse oil gallery, on the flywheel end main bearing the oil drilling goes in about 3"then stops about an inch from the gallery, spraying brake cleaner down the oil drilling proves that oil gets to the transverse oil gallery, (this is the block that did about 21.5k of very hard miles in my ownership) is there a restrictor with a tiny hole in it down there. Same on my 'new' block. is this because there isn't a cam oil feed from the main bearing like the front 2
Just asking

[imack]

The ' blockage' is the oil pressure relief valve seat. Oil flows from the main gallery, around the seat and the to the main bearing.
Somewhere online there's a picture of a sectioned a series block showing the oil path at the relief valve end of the block. It shows how the 'waisted' relief valve seat allows oil flow to the main bearing.
I've not been able to find the picture.

[BAD942B]

The ' blockage' is the oil pressure relief valve seat. Oil flows from the main gallery, around the seat and the to the main bearing.
Somewhere online there's a picture of a sectioned a series block showing the oil path at the relief valve end of the block. It shows how the 'waisted' relief valve seat allows oil flow to the main bearing.
I've not been able to find the picture.

then they must have machined an anulus then pressed in the OPRV seat afterwards

[BAD942B]

I wondered how they got round the OPRV drilling, hadn't thought of that

[1071bob]

This one? You can remove the PRV seat with with a threaded rod.

[BAD942B]

even cleverer

[BAD942B]

looks like the seat is pressed in to a depth rather than up against the step

[imack]

This one? You can remove the PRV seat with with a threaded rod.

Yes, that's the one I was looking for.

[Peter Laidler]

Sectionalised things like that block reminds me of the stuff that we used to sectionise as 60's era engineering apprentices. Usually a group of 5 or so would be given a task to discuss what was needed, how and to get on with it!

A lot of these examples of past apprentices work was on display in the training schools or presented to visiting dignitaries...... Alas, none of my groups work met with such acclaim. After being marked, it probably went into the scrap

I wonder of they do it now........ Maybe not!

[Spider]

I always pull the seat before sending the blocks out for cleaning and machining and only re-fit them after the final shop cleaning. There's no other way to clean that end of the block.

[MiNiKiN]

This one? You can remove the PRV seat with with a threaded rod.

The obvious question to follow: what is the thread size? 5/16 UNF maybe?

[GraemeC]

Whatever you make it - its not threaded to begin with

[BAD942B]

This one? You can remove the PRV seat with with a threaded rod.

The obvious question to follow: what is the thread size? 5/16 UNF maybe?

far bigger than that, bore size is originally around 8mm but as Graeme says its not threaded to start with

[BAD942B]

I guess the real question is can you buy them

[BAD942B]

MiniSpares list them 2A797

[MiNiKiN]

I lost control of my life - CUT! - parts stock I mean of course.
I just recently bought this along with a new oil pressure release valve (read: not ball)

[Spider]

I tap them 3/8" UNC and use a head stud and a socket as a spacer to pull them.

I guess the real question is can you buy them

999 times out of 1000 I reuse them.