Author Topic: 1952 A7 oil to rocker box  (Read 2325 times)

Offline anjimehra

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1952 A7 oil to rocker box
« on: 28.01. 2017 13:32 »
Hi guys
Just started up the basket case A 7 today & she fired up instantly & soon settled down to a steady fast tickover. One problem. Very little oil going into the rocker box, resulting in too much clatter. Rocker box dry. Closed the hole in the return pipe & a a little oil seeped out from the sides of the rockers. Tappets remained dry & no oil going down to the camshaft. Assuming holes in rocker shaft clear as newly assembled. To the best of my knowledge there should be a lot of oil spraying around in the rocker box. Any suggestions  Thanks
Anji

adm edit: title edited to reflect topic content

Offline stu.andrews

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Re: 1952 A7 oil to rocker box
« Reply #1 on: 28.01. 2017 14:57 »
No, there should not be a lot of oil up top as it will run down the valve guides & burn. A little oil should be up there so I would see if there is any restriction in the feed.
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Offline muskrat

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Re: 1952 A7 oil to rocker box
« Reply #2 on: 28.01. 2017 18:24 »
G'day Anji.
As Stu said a lot of oil is no good but how much is just enough? I've never measured the oil flow to the rockers. I'll be doing a bit of work on my 51 A7 this week so will run a test.
Cheers
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Online Klaus

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Re: 1952 A7 oil to rocker box
« Reply #3 on: 28.01. 2017 19:10 »
My experience is another. There is a lot of oil coming out from the oilfeed banjo. Open the inspektion covers and you can seethe oil runimg down from the rocker spindels. The most oil is feed to the exhaust rockers were the oil is spreading out by running a few minute.
The cam is running in a tube filled with oil so the cam is well lubricated as the camfollowers too. Oil from the inlet rockers going down the push rods  to the top of the followers and through two holes back in the crankcase. So check the connection from the oilfeed junktion ift they is free off dirt.

cheers Klaus


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Offline anjimehra

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Re: 1952 A7 oil to rocker box
« Reply #4 on: 29.01. 2017 06:33 »
My experience is another. There is a lot of oil coming out from the oilfeed banjo. Open the inspektion covers and you can seethe oil runimg down from the rocker spindels. The most oil is feed to the exhaust rockers were the oil is spreading out by running a few minute.
The cam is running in a tube filled with oil so the cam is well lubricated as the camfollowers too. Oil from the inlet rockers going down the push rods  to the top of the followers and through two holes back in the crankcase. So check the connection from the oilfeed junktion ift they is free off dirt.

cheers Klaus

Thanks Klaus. Have checked oil at banjos & it's getting there. Have also blocked the return hole in the oil tank & a little oil seeps out from the sides of the rockers but stops when I let oil flow back into tank. Because of this no oil reaching the camshaft & tappets. Engine newly reconditioned
Anji

Offline anjimehra

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Re: 1952 A7 oil to rocker box
« Reply #5 on: 29.01. 2017 06:40 »
G'day Anji.
As Stu said a lot of oil is no good but how much is just enough? I've never measured the oil flow to the rockers. I'll be doing a bit of work on my 51 A7 this week so will run a test.
Cheers

Hi Muskrat
Agreed, too much oil counter productive, but it's not even getting to the tappets & the camshaft is running dry as no oil is draining down via the pushrods tube. The rocker shaft oil galleries appear clear as oil seeps out of the sides of the rockers if I block the return hole in the tank. Totally foxed !!
Take care, Anji

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Re: 1952 A7 oil to rocker box
« Reply #6 on: 29.01. 2017 07:01 »
Have you checked there is plenty of oil returning to the the oil tank?

A proportion of the oil returned to the oil tank is bypassed to the rockers, by the action of a slight restriction placed in the return where it attaches to the oil tank, the restriction will hardly be affecting he return rate, as if needs be, the return side of the pump could reach the same psi as the feed side, in practice it doesn't, as there is very little restricting the oil flow back to the tank.

A rocker feed copper pipe with too small an I.d. Might slow the oil supply down?
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Offline Rocket Racer

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Re: 1952 A7 oil to rocker box
« Reply #7 on: 29.01. 2017 07:10 »
keep in mind the camshaft runs in a bath fed if I recall by the feed from the pressure bypass valve on the front of the cases, so shouldn't be running dry and doesn't rely on the rocker feed for oil. The cam follower shafts are lubricated by the drain from the top end.
If blocking the return hole in the oil tank sends oil to the rockers then thats what I would expect, the main function of the oil is for lubricating the spindles.
Many prewar machines ran dry top ends and a rocker oil feed was only introduced for the late c11's.
For a rebuilt motor the top end should have been liberally primed with oil and once the engine is above idle the higher pressures should be sufficient.
The most common problem with top end oil lines is leakage.
Is an after market in line oil filter fitted on the return side?
If you loosen a rocker oil nut slightly does it weep? It should

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Online Greybeard

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Re: 1952 A7 oil to rocker box
« Reply #8 on: 29.01. 2017 09:04 »
Many prewar machines ran dry top ends...

Am I correct in thinking that the early A's had no rocker oil feed?

Online bsa-bill

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Re: 1952 A7 oil to rocker box
« Reply #9 on: 29.01. 2017 10:11 »
Quote
Am I correct in thinking that the early A's had no rocker oil feed?

Yes GB I think most early bikes had no feed to the rockers and indeed no covers on them either, possibly they got a squirt from an oil can before a journey and maybe some sort of misting device (not sure about that one).
Other forms of lube could have been - reservoir and wick - grease pot with screw top (you know what I mean)
Covers may well have to keep the rider clean
All the best - Bill
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Offline duTch

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Re: 1952 A7 oil to rocker box
« Reply #10 on: 29.01. 2017 11:15 »

 
Quote
Am I correct in thinking that the early A's had no rocker oil feed?

 I think the first 'A7 Vertical Twins', and some singles had feed to one rocker (ex?/In *????*), but not the other   
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Online Bsareg

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Re: 1952 A7 oil to rocker box
« Reply #11 on: 29.01. 2017 13:29 »
C11 handbook says "top end is lubricated by oil mist". Possibly  OK if used engine gets good and hot but doubtful when used for short journeys, maybe this is why they added an oil feed later. I fitted the mod to my  C11 in 1964 and could hear the difference a proper oil feed made
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Online chaterlea25

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Re: 1952 A7 oil to rocker box
« Reply #12 on: 29.01. 2017 21:48 »
Hi All,
Going back to the original question..

Anjimehra
What size holes are in the banjo bolts ?
I know that there are quite a few different size drillings to suit various models ?
Next Question, does the early A7 have the same size drillings as the late A7/10 ??

John
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Offline muskrat

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Re: 1952 A7 oil to rocker box
« Reply #13 on: 03.02. 2017 08:52 »
G'day All.
I just did a flow test on my 51. Opperating temp, fastISH idle, before banjo's. New 25/70 oil & KN153 filter in line before rockerbox junction, 2 beers after work!
2 minutes = 12ml. So not a loy.
Cheers
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Offline anjimehra

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Re: 1952 A7 oil to rocker box
« Reply #14 on: 05.02. 2017 11:18 »
Hi Muskrat & Chaterlea25
Sorry for not responding earlier, but just got time to go back to the bike. Heres what I have checked:
1) Loosening the banjo nuts indicates oil reaching the end of the rocker spindles. Closing the return hole in tank increased pressure Inserted a a washer with a smaller dia ( 2mm ) hole in the return pipe to increase pressure to rockers. Ran the engine for 5 mins on fast idle. No oil present in the rocker box. Tappets etc bone dry
2) Dismantled the rocker box & checked spindles for blockage. All clear
Engine very noisy. Suspect no oil reaching camshaft & timing gears also. How do I check if the relief valve is operating w/o a pressure gauge? Will malfunction of relief valve cause excessive valve gear noise?
By the way, return oil is coming in bursts, as I think it should, considering return pump capacity = 2 x feed pump

HELP !!
Thanks
Anji