A10 Rocker box differences (solved)

[Bsalloyd]

 I am just starting to assemble my 1962 RGS engine. The bike came with a lot of spare parts including five rocker boxes. I went to the parts books and found that there are numerous iterations of this part. I am assuming that the difference may be in the distance between the rocker spindles and possibly the height from the center line to the base. Can anyone advise which box would fit my bike?

[Billybream]

I think you will find that the difference is mainly to provide clearance for larger valve springs associated with alloy heads.
I purchased  one recently of Ebay and was just lucky it suited my bike.
Best check with dry assembly and pay attention to all threads as they have history of stripping.

[JulianS]

Three basic rocker boxes;

First A7 A10 iron head basic box with short fixing studs.

Second A7 Shooting Star basic box with long fixig studs.

Last A10 Rocket engines, long studs but as Billybream says extra machining on the inlet side to basic box clear wider rocket valve springs.  You can see the extra machining in the photo.

Despite the extra machining the same gasket was specified.

[duTch]

 Hiya lloyd - my phone died earlier when I read this.....what they already said, mainly the spring cutaways, but I fitted a Plunger model cover onto a later big valve head/sprigs no probs...(using the obvious 'other' bits).....

 Ps; just between you and me, you better sneak over to the 'introduction page' before yo're sprung... (I won't tell)

[Seabee]

I think you will find that the difference is mainly to provide clearance for larger valve springs associated with alloy heads.
I purchased  one recently of Ebay and was just lucky it suited my bike.
Best check with dry assembly and pay attention to all threads as they have history of stripping.
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I love learning something new!uote]

[Bsalloyd]

Thanks everyone for the great information. From your comments I believe I can use any of them with the correct studs installed. I had the head rebuilt with the beehive springs so it is very small at the top end. Lloyd

[Swarfcut]

Hi Lloyd,  I  find it a whole lot easier to replace the rocker box with no vertical studs fitted. This gives a bit more lateral movement to get the box round the valve caps and springs, plus makes pushrod location easier. Trick here is to make sure the studs go in nice and easy with finger pressure beforehand. Also to have some gynaecological skill working in confined spaces.

Swarfy.

[Bsalloyd]

Hi, Swarfy. I kind of got that idea from the comments. Thanks for confirming it. I could have used this hint when installing a rocker box on an Ariel Huntmaster last year. What a job! Lloyd