Oil Gallery Screwed Plugs

[philthehill]

There has been some correspondence on this forum regarding replacing the oil gallery plugs with my preference to replace the knocked in plugs with screwed ones.
I have just finished fitting screwed oil gallery plugs in my spare 1275cc 'A' Plus block - but all of the blocks that is 948cc, 1098cc and 1275cc can be treated the same.

I have used parallel 5/8" UNF blanking plugs from Mini spares for the main fore and aft galleries

http://www.minispares.com/product/Class ... c/manifold blanking plug.aspx|Back to search

and 5/16" x 1/2" & 5/16" x 3/4" UNF grub screws for the horizontal/vertical oil galleries that take oil from behind the oil pressure relief valve to the sump.
As photos say a 1000 words I took some photos whilst doing the job.

Photo No: 1.
As the tapping drill is 14.5mm and the drill is quite powerful I decided to secure the block to the drill in case the drill picked up and threw the block to the floor. It is recommended/advised in the engineering text books that when using a drill above 1/2" the item being drilled should be secured to the drill or drill stand.[frame][/frame]

[philthehill]

Photo No: 2.
The depth of the drilling is determined by the length of the blanking plug and the placement of the interconnecting oil galleries.[frame][/frame]

[philthehill]

Photo No: 3.
When tapping ensure that the tap is vertical by putting an engineers square to the tap on several sides.[frame][/frame]

[philthehill]

Photo No: 4.
Use the 1st cut tap then the 2nd cut tap and then the plug tap.[frame][/frame]

[philthehill]

Photo No: 5.
Front of the fore and aft galleries completed.[frame][/frame]
When fitting the screwed blanking plug on the distributer side of the engine make sure that the blanking plug does not obscure the oil gallery from the main front and aft gallery to the front main bearing. If necessary take a little off the inner (cone) end of the blanking plug to ensure that there is no obscuring of the gallery to the front main. To confirm all is clear put a 1/4" dia rod through the gallery from the front main end of the gallery and then fit the blanking plug - if the rod is not nipped the gallery is clear all through - if not reduce the blanking plug accordingly.

[philthehill]

Photo No: 6.
The rear gallery by the oil pressure relief valve has to be drilled shallow and the blanking plug reduced in length to allow the rear engine plate to fit flush.
It has to be drilled shallow because an oil gallery intersects close to the rear face of the engine.
Thankfully It does not have to be drilled that shallow for the screwed plug to be ineffective.[frame][/frame]
Picture No: 6a.[frame][/frame]
To allow the rear engine plate to fit flush the other rear (non distributer side) fore and aft gallery plug has to be reduced in length (allen key end) to sit flush or just under the rear engine face.

[philthehill]

Photo No: 7.
The two 5/16" UNF blanking plugs for the galleries releasing oil from the rear side of the oil pressure relief valve.[frame][/frame]
When the original gallery plugs were removed the galleries were found to be seriously fouled with crud - so whether the original type knock in plugs or screwed plugs are fitted it is most important to clean the galleries when re-building the engine.

[Declan_Burns]

Excellent Phil,
Photo No. 7 is just what I was looking for. Did you use brushes to clean out the swarf? Did you rinse the galleries and if yes what should be used?
Regards
Declan

[philthehill]

Declan.
Thanks for the positive comment and I am glad you found it of help.
Whilst drilling I used a 2000 watt vacuum cleaner to pull the swarf/chippings away from the drilling.
When cleaning the main for and aft galleries I use a long brush which I purchased many years ago from http://www.frost.co.uk which will go right through the galleries (and beyond) from front to the back of the block. Unfortunately they do not seem to do that length of brush any more.
The other galleries are also cleaned with various sized brushes which are still available from Frosts - product code C170 set of 4.
As regards what I use to clean the block I generally prefer to use paraffin applied both with a stiff brush and in a air spray gun.
The block is then washed down with a hose and completely dried with an air line.
If I feel that I need to use say GUNK I will - and again I will use a hose pipe to clean off/remove.
There is no problem as regards using a water hose so long as the block and galleries are completely dry when the job is completed.
Cleaning the block is made easier and allows for a much better job with the core plugs removed,
As I am very meticulous when cleaning the block (and other engine parts also) - It can take me several hours to complete. It takes however long it takes even if it takes all day.
When the inside of the block is completely de-greased and I mean completely de-greased and dried I paint the inside of the block with GLYPTAL (again available from Frosts) as it does make the inside of the block smoother and allows the oil to drain to the sump quicker.
Some people have experienced the GLYPTAL (or similar) lift off the casting but I have never had that happen. The secret I believe is to totally de-grease the block. Any grease remaining will not allow the GLYPTAL to adhere to the block.
I hope that the above is of help.
Phil

[Roni]

A suggestion for the brushes, if you are finding them hard to find, is to look at gun cleaning supplies for the bore brushes.
Good modification to the block too. I have had a leaking plug, aluminium, fresh from the re-conditioner.

[philthehill]

Tried my local gun cleaning supplies shop and nothing small enough.
Plenty of the required item on 'e' bay but all in the USA.
The long brushes required were acquired from Eastwood http://www.eastwood.com/engine-brush-kit-set-of-4.html via Frosts Restoration some time ago.
Anyway - I have overcome the problem of the lack of availability of long brushes by taking the correct diameter brush supplied by Frosts restorations, run some solder into the last 25mm of the twisted wire handle, cut off the original loop at the end of the handle, taken a suitable length of pipe and soldered the brush handle into the end of the pipe. I put a loop into the non brush end of the pipe to make a handle.
I now have a long handled oil gallery brush that will reach right through the fore and aft oil galleries on the 'A' Series.
It works well too

[Declan_Burns]

Good idea Phil,
Regards
Declan

[philthehill]

http://www.ajreeves.com/flue-brushes-277-c.asp

The 24" length is more than adequate for the fore and aft oil galleries.

[les]

Phil, if I could refer you to photo 7, on my block there appears no evidence of the hole at the sump/block face being plugged, yet this photo shows you having a threaded plug screwed in. I'm wondering if, in fact, it originally relied on the sump to seal the hole. Is this correct, or another case of me forgetting I had removed a press in plug in the distant past?

[philthehill]

Les
There should be a plug in that hole whether it is pressed in or a screwed plug. The block shown did have a brass plug pressed into the hole which was drilled out and replaced with a screwed plug.
The vertical gallery feeds from the back side of the oil pressure relief valve so that any oil that gets past the release valve piston is allowed to drain back into the sump via the horizontal oil gallery (which is shown plugged & is located halfway between the oil pressure relief valve and the sump gasket face) and the main oil pressure relief valve drain.
If the drain off oil gallery was not there the oil pressure acting on both sides of the relief valve would be the same and the valve would not open. For the oil pressure relief valve to work correctly the pressure must be less on the back side of the piston.
See attached photo below:-

Phil

rear oil galleries.jpg (97.47 KiB) Viewed 5075 times

[les]

The ital block must have had a plug then. Looks the same colour all the way down the gallery even where the plug must have been, this is what puzzled me. However thanks for clarifying this Phil.

[philthehill]

Les
I suspect that the plug has been left out at some time in the past.
No matter - the oil pressure behind the oil relief piston would be very low anyway as most of the oil bypassing the valve will be returned directly to the sump via the front of the oil relief valve piston.
Only the main fore and aft oil gallery plugs are listed in the BL Marina parts list - the vertical oil galley plug may have been removed and subsequently it was found that a new vertical gallery plug was unavailable and the fall back position of using the sump gasket as the blocking/sealing medium was decided upon.
I am certain that all the 'A' Series blocks had the vertical oil gallery blocked with a brass plug. Both my 1275cc Midget block and if I remember correctly my 948cc Minor block had brass plugs in place and all were replaced with screwed plugs.
I am just about to start stripping a 948cc Sprite engine and it will be interesting to see what oil gallery plugs are fitted (or not). The oil gallery plugs in the Sprite engine will be replaced with screwed plugs.
All the 'A' Series engines have similar oil gallery arrangements as featured in the sectioned block photo.
Phil

[les]

That's quite interesting, I want to get this right, looking at the sectional photo, if I'm reading it right, there are two vertical galleries exiting to the sump flange. I've just now checked my block, and I see, again referring to picture 7, that the vertical gallery to the far left on my block, is blanked of with a brass plug. In which case the gallery we are suggesting should be plugged is the only one available that drains to the sump. In fact it is clear of the sump gasket to enable drainage. So from this, I think it is intentionally left open.

[philthehill]

Les
There seems to be confusion as to what the two vertical oil galleries do. No 7 picture shows a screwed plug being fitted to the bottom of the outer small diameter vertical gallery.
Only the outer vertical oil gallery meets the sump flange at its lower end where it is blocked by a brass plug. The inner large diameter gallery is open to the sump.
The inner fully open vertical oil galley you refer to is in fact the oil pressure relief valve main drain i.e. when the oil pressure overcomes the oil pressure relief valve spring the valve is pushed outwards off its seat and the surplus oil drains back to the sump. Most of the time oil is flowing down this oil gallery when the engine is running and the engine has oil pressure.
Both vertical galleries eventually drain to the sump but the oil at the rear (outer side) of the pressure relief valve drains to the sump via the vertical and horizontal oil galleries (the horizontal gallery is plugged from the outside of the block) and out into the main oil pressure relief valve vertical drain .
To reiterate - the main oil pressure relief valve drain (inner) has to be left open for the excess oil to drain back to the sump.
Phil

[les]

From the photo, I mistakenly took it you were plugging the larger of the two vertical galleries. I think we are singing from the same song sheet now!!