Alloy head Rocker box

[bsa-bill]

I have been told about this by forum members but it's a case of a picture is worth a thousand words when getting stuff into my rocker box.
This link shows quite nicely the difference for the Rocket Rocker box where it is relieved for the springs, I had not understood this entirely and was looking in the wrong place on my bike, so when the head needs torqued down I will address this

http://bsa-a10.hailwood.com/thehead.html

[LJ.]

Bill have you got a part number handy for the alloy head Rocker Box? I have a few boxes and now need to go and check them all out.

[bsa-bill]

I'll check in the shed today LJ, I bought an (alleged) Rocket rocker box but broke out a stud hole while fitting new studs (Draganfly supplied wrong studs), I used another box but did not check the valve spring clearance at the point in the article, this might even explain why I had a little bit of valve sticking.

I was led to believe the difference in the part numbers was down to the rocket rocker box having longer studs for the alloy head but this article would prove that to be wrong.

[redbeeza]

Why did I look at this post?  Now I think I've fitted the wrong rocker box!  I changed the rocker box on my SR because the mating face with the head was very chewed up amd leaked oil.  I got a better one from Newark AJ.  It has fitted OK and the engine runs but I haven't had it on the road yet.  Does this mean something catastrophic will happen when I open the bike up on the road?

The box I removed was numbered 67-200 (I think, it is quite hard to read and probably isn't likely to be 67-800).  Of course I can't guarantee that this is the original box; there certainly wasn't much else original, or correct, on the bike.  I can't remember the number of the replacement box that I have now fitted to the bike, but it wasn't the same, it was 67-1**.

I've just had a look at the 67-200 box and it looks like material has been ground away (in fairly amateurish way) in the region annotated in the photo.  It also looks like the top of a spring/retainer has clouted the box on one side, high up above the ground away area.

[bsa-bill]

Well if my box is wrong Redbeeza I doubt if anything catastrophic is going to occur as mine has been out and about on half a dozen occasions with journeys of  upto ten miles.
The sticking valve issue was found when turning the engine over by hand and I think was probably caused by one of the front primary case screws binding on the crankshaft , possibly the valve spring might have also contributed - don't know.
Anyway it runs well enough that I'm not at all bothered by it but will check it out when I tighten the head down, I won't be twisting it's tail for anytime soon anyway

LJ sorry but I have to go into Berwick this afternoon so could be tomorrow before I get the r/box's checked

[Rocket Racer]

My understanding is that the alloy head rocker boxes have the original cast number overstamped. 

[bsa-bill]

Hi Rocket Racer - yes as quoted in the article

They are identifiable by the manual stamping of the part # on the underside

If the difference is just relieving a bit for the springs then I would assume BSA would just do this in house to normal rocker boxes then overstamp them, so all you need is a Dremel and a few minutes and a set of longer studs to modify a normal box.

I bought a so called Rocket rocker box of Ebay, this is the one I broke out a stud hole in so discarded it, I'll check it today for over stamping ( must have done this already I think but memory ? )

Can't believe an Ebay seller would sell me something other than advertised 

[1660bob]

Well i never..... I just looked at mine-it Should be a S/R type but it isnt,but its not got good threads anyway.Imagine my surprise when i drag out the replacement i bought off Fleabay thinking at the time that the only difference was the studs, and the replacement IS an S/R type-ground back in the areas stated, it has a hand stamped X close by the cast in part number.My only worry-there are three part numbers in the parts book-one for theA7/ A10, one for the S/R and one for the A7ss- anyone know what the difference is for the A7ss? Bob.

[bsa-bill]

Just checked my spare box's in the shed and there all standard so unless the one on the project is the one I bought I don't have a Rocket box.
Forecast is to get a bit warmer so as I have a leak somewhere around the Rocker box it might be a good idea to remove it next week and modify it whilst it's off, would be so nice if the roads dried and I could run it up and down to get the engine warm then could tighten head down as well - ( one can dream )

The leak is a small one, there always seems to be a bit of oil around the head bolt just behind the spark plug on the drive side, the rest of the head is clean, it also seems to happen when the bike is in the shed idle, defo not coming from the rocker oil feed

Bob -  just a thought - as the A7 SS box will have longer studs for an alloy head but perhaps not relieved like the Rocket one it might then have a different part No 

[muskrat]

Bill, think you may be right about the SS box as they don't have the larger springs etc.
Just noticed you have gone over the 1K posts, congrats.
Cheers

[bsa-bill]

Just noticed you have gone over the 1K posts, congrats.
Cheers

I think it you lot that need congratulating for putting up with my 1K ramblings

[LJ.]

Bill... I had a look at all my rocker boxes and most seem to be 67-208 one is a 67-206 but its damned hard to make out the difference between the 6 and 8 even with a magnifying glass. Also spent the day looking at other rockerboxes at Newark & Notts autojumble most of what I see are the 67-208.

[trevinoz]

I would like someone to measure the difference between the "standard " box and the "alloy" box".
I have never seen a box with the over stamped number and don't have any problems with spring clearance on any alloy head engine which I have.
Perhaps these boxes were early production and all were made later to suit all engines.
Trev.

[LJ.]

Trev... Looking at the two I have, I did not even bother to get the vernier gauge out as they both looked identical.

[bsa-bill]

Had a very close examination of the valve springs and clearance to Rocker box this afternoon, I can't really see where there could be a problem, bit difficult to be 100% as my torch was running out.
Anyway I've got out of jail with Kitchen unit job due to a sort of Siatic leg so can't do much other than in short bursts between morphine hits (do I hear violins) so I think I'll have the box off and get a mirror or two and see if can shed some light  (pun intended) on the box clearance, could even be a Rocket one that is on.
Could also be BSA changed the box dimensions after Rocket alloy heads.

Also got a job to do on the barrels, the rear two stud holes are almost shot, I got over it last by turning down some cast head bolts so they would engage threads further down into the barrel.

One day - one day I'll finish this thing