B31 oil pipe banjo bolts

[Brad837]

There are posts about these but none answer my query. Bought some oil pipe banjos at Newark for my 1959 BSA B31. So, the two items at the top are the original items removed from the oil return pipe, with the large drilling, which I believe is correct. However, they were screwed direct into head without any washer between banjo and head, is that right?

Also, the two on the bottom row at left are my original items removed from the rocker feed pipe, and on the right, the two replacement items bought. As you can see, these oilway drillings on the replacement items are very small compared to my originals. The vender says these replacement items do have the correct small hole size, but says it is recommended that the one fitted to the exhaust side be opened up. So which size hole is right, my originals or his replacement. Any comments welcomed.

[Pete C]

correct, no washers are needed.
the vendor is also correct and I think your originals are 2 exhaust items with the larger hole than the inlet.

[Pete Gill]

An interesting thread for me as when i rebuilt my 1949 B31 engine i was concerned that the very small ?1/64" hole in the rocker feed bolt was too small. I feared that such a small drilling might be easily blocked by even the tiniest of debris so i drilled it out to open it up a bit.
I wonder if the top end is over oiled now? although i do not get any evidence of oil down the valve guides - no smoke-  i do get quite a bit of oil spiting from the breather tube and now wonder if this is due to excessive oil draining down over the timing gears adjacent to the breather tube.
Has anyone experienced this? I have bought some new replacements and intend to change them back to original specification to see if this helps - but i would be interested to see what others think or have experienced in this matter.
Pete

[idie]

The small hole for the inlet valve.

[Rog1]

The small hole for the inlet valve.

Then I did the right thing last week. I was surprised to find my rocker feed bolts had different sized holes, so I used the one with the smaller hole for the inlet valve, as you said.

[martinh10]

BSA specified the same part (65-317) for both inlet and exhaust rockers (~1/64" dia hole) and part 26-1253 (~3/32" dia hole) for the top and bottom of the oil return pipe. My B31 had the latter fitted to both rocker feeds when I got it. I can't say I noticed any difference when I changed them for the correct items.

[idie]

The bolts for the oilseed are the same as those for the A series. My M33 and myB33 both have the larger hole for the exhaust

[Ian C]

I'd like to know where this larger hole for exhaust oil feed came from? As martinh10 posted, part numbers were the same for both rocker feed banjobolts, plus BSA stated on their Service Sheet 303 as attached. I rebuilt my M33 using smaller hole bolts for rocker feed and larger for drain as 'You ought not to put more in that you get out'. Also don't forget the washers that go between the rocker oil feed banjos and cyl head (p/n 31-8430)

[idie]

The drain bolt has a very large hole

[Pete C]

I'd like to know where this larger hole for exhaust oil feed came from? As martinh10 posted, part numbers were the same for both rocker feed banjobolts, plus BSA stated on their Service Sheet 303 as attached. I rebuilt my M33 using smaller hole bolts for rocker feed and larger for drain as 'You ought not to put more in that you get out'. Also don't forget the washers that go between the rocker oil feed banjos and cyl head (p/n 31-8430)

good point on the hole sizes. I can't remember who told me to use a larger hole on the exhaust side. I have a number of these bolts with all different sized holes   

[idie]

I have had my. B33 50 yes.Always with larger hole on exhaust feed. If it ain't  broke!

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[Calum]

My B31 had the small hole banjos on the feed pipes and on the bottom return banjo where it goes into the crank casing. The result was an embarrassing smoke screen at traffic lights etc after moving along at speed. The oil pump would be filling the rocker boxes with oil which couldn't drain fast enough!
Checked the banjos after a suggestion on here. Annoyingly the bottom one of the return pipe hits the inside of the primary before coming out so I had to remove the primary just to move it 1/8" or so. I drilled the banjo out to match the other and it instantly cured my problem. I shortened the threaded portion slightly too so it can be removed with the primary in place in future if needs be.

As said no washers, they seal on the tapered faces. Mine were all all scored/poor finish so I refaced then in the lathe to aid sealing and I've had no leaks from them.