Author Topic: Not for the faint hearted  (Read 901 times)

Offline morris

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Not for the faint hearted
« on: 05.01. 2014 22:15 »
Finally got round fixing an oil leak at the rocker box base of the SA.
Couple of hours...nice cuppa in between...job done!
Well....no *problem*
Below a pic of the bolts and some fine examples of the studs that came out. I mean who the hell and what the f***...
Threads in the head and rocker box are knackered, so that 'll be a helicoil job.
The rocker box itself leans to the left, so the tappets are out of centre on the valve stems. The part number I found on the bottom points towards an earlier ('52-'55) type while the head is I think at least 1960
I am thinking of shimming the rockers instead of using the spring washer to get the tappets nicely centred on the valves.
Has anybody got any advise regarding on how much end float to use when shimming?
Thanks
'58 BSA A 10 SA
'52 BSA A 10 Plunger
'55 MORRIS ISIS
The world looks better from a motorbike
Belgium

Offline muskrat

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Re: Not for the faint hearted
« Reply #1 on: 06.01. 2014 08:46 »
G'day morris, they only need a couple of thou float. It gets bigger with warmth.
The box's are the same right through for the iron heads but the later SR type had the casting # over stamped and the castings were relieved around the ex valve area. If it has been excessively faced and at a slight angle I'd bin it. 2nd hand ones on fleabay go cheap.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline morris

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Re: Not for the faint hearted
« Reply #2 on: 07.01. 2014 07:45 »
The box's are the same right through for the iron heads

Thanks Musky.
That's what I thought also.

I should have expressed myself better when I said it was leaning to the left. I did not mean at an angle, but out of centre.
I think at some point someone re-drilled and rethreaded the holes in the head, as I found the thread inside the head looks to be BSF.
That someone didn't do a very good job because the holes in the box don't seem to line up very well with the ones in the head, so I think the head's scrap to *eek*
'58 BSA A 10 SA
'52 BSA A 10 Plunger
'55 MORRIS ISIS
The world looks better from a motorbike
Belgium

Offline muskrat

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Re: Not for the faint hearted
« Reply #3 on: 07.01. 2014 08:46 »
That's a bugga and expensive. *pull hair out*
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline bikerboy

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Re: Not for the faint hearted
« Reply #4 on: 18.01. 2014 21:42 »
I dont think you need to scrap the head. I had a head where the alloy was split all around the brass inserts. I broke the brass thread plugs out and a good alloy welder welded them up to give me a nice surface to heli coil. I only heli-coiled because I thought it would be a bit stronger than a thread tapped into alloy.

Anyway it saved the head which nowadays is a big money saving.

Offline morris

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Re: Not for the faint hearted
« Reply #5 on: 18.01. 2014 22:42 »
Thanks for the advise Bikerboy. In the mean time I've been offered a head at €100 (£80) so I think I'll go for that option, and eventually try to get the actual head repaired to have a spare
After investigating a bit further, I found the threads in the head where rethreaded to 5/16 BSF as this size bolt went in easily. I think this was done to insert 1/4 BSW helicoils.
Because one of the holes has been welded up and tapped to 1/4 BSW (hence the long 1/4 BSW stud in the picture) I think the rocker box must have been held on at some point with four 1/4" BSW studs.
Later someone must have tried to force in three "correct" 5/16 BSC bolts and in doing so forced the helicoils down the bottom of the hole, because when I passed a 5/16 BSF tap through the hole it went in easily until about 1/4" from the bottom where it hit something hard which seemed to be some remains of helicoils. I tried carefully to drill the remains of the helicoils out, but only succeeded partially.
For the moment, to get the thing going, I drilled and tapped the 4th hole to 5/16 BSF and bolted the box down with four BSF bolts.
As it says in the title; not for the faint hearted......
'58 BSA A 10 SA
'52 BSA A 10 Plunger
'55 MORRIS ISIS
The world looks better from a motorbike
Belgium