The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: sean on 13.02. 2020 17:54

Title: valves 1962 super rocket
Post by: sean on 13.02. 2020 17:54
hi
having trouble finding the part number (and the parts ! ) to replace my valves and guides and springs on my 1962 super rocket .
head casting .....67-1549
in the parts breakdown they list 4 different part numbers for the intake valve and 3 different numbers for the exh valve with no mention of which head casting or year they fit or size .
I would like to buy a complete kit from one supplier ....prefrably Canada or USA .
my intake valve measures 1.455 my exh valve measures 1.380 across the valve face.
i was under the impression all big valve engines were 1.500 .
any recommendations on parts and suppliers would be a big help.
tia
 sean
Title: Re: valves 1962 super rocket
Post by: chaterlea25 on 13.02. 2020 20:21
Hi Sean,
Quote
i was under the impression all big valve engines were 1.500 .

I have seen 1549 heads with 1.5in valves and 1571 heads with 1.45in diameter head valves so It is not an exact science
A forum search might reveal previous discussions on these heads and valve sizes

Sorry do not know who stocks them over there
SRM in Wales have high quality hardened valves and all the other bits to suit

John


Title: Re: valves 1962 super rocket
Post by: sean on 14.02. 2020 14:12
srm dont list valve sizes or part numbers on their web site 
but thanks for the reply
Sean
Title: Re: valves 1962 super rocket
Post by: Swarfcut on 14.02. 2020 14:47
sean,
    Try Alpha Bearings. They have an online catalogue for valves and guides, but like everyone else don't list dimensions. A further problem is that recently the company has gone through a bad patch, and although the website and contact details look fine, I do not know if the company is still trading.      Website www.alpha-bearings.com   May be worth a look anyway, lots of goods stuff there.

 Valves can be dimensionally the same, but have different part numbers to identify a change of material or something  as simple as a variation in collet groove.

 Swarfy
Title: Re: valves 1962 super rocket
Post by: Klaus on 14.02. 2020 15:56
SRM had this valves:

http://www.shop.srmclassicbikes.com/product/inlet-valve-a10-1-12-38mm-plasma-hardened-rgs-670961


chees Klaus
Title: Re: valves 1962 super rocket
Post by: sean on 14.02. 2020 16:02
thanks for the reply

 srm valve is 1.5 mine are 1.455 on the intake
1.380 on the exh
at this point dont mind where they come from except india
I dont know if my valve seats can be cut back to accept the 1.5 valve set
Title: Re: valves 1962 super rocket
Post by: Klaus on 14.02. 2020 16:18
This valves are not from India. I do run this 38mm valves on my race bikes with no problems.
Title: Re: valves 1962 super rocket
Post by: trevinoz on 14.02. 2020 22:09
I think that the valve sizes are actually 37mm & 35mm.
Title: Re: valves 1962 super rocket
Post by: chaterlea25 on 14.02. 2020 22:30
Hi Sean,
SRM list both size inlet valves 67.1551 and 1.5in  67.0961 (SRM215 )

It takes very little seat cutting to accommodate the  bigger valve, so if the seats are in any way pocketed the bigger valve will be fine

Last week I was working on a 52 Star twin cylinder head where the seats were pocketed and the exhausts fairly pitted
After cutting the seats just enough to get a good surface the original valves were well recessed  *sad2*
Options
fit seat inserts ?
live with it?
find some larger head valves?

A trial fit of an A10 exhaust valve looked good, and the heads could be reduced if necessary?
Yesterday the new A10 valves arrived and a quick lapping showed that they were seating nicely and no machining needed
I will need to check clearances between the valves and valves to pistons but I do not anticipate problems

The Star twin head inlet ports looked quite different to each other ????
One looked to have very little "meat" behind the seat area to support a seat insert if one was going to go that route
Maybe those odd ports are a reason why some BSA's show cylinder bias *????*

John



Title: Re: valves 1962 super rocket
Post by: sean on 14.02. 2020 23:53
thanks for the reply
my valve seats are fine  .... no pitting , i dont think the extra 60 or so thousandths of an inch is going to make a great difference and not really looking for performance on a 58 year old engine just reliability if possible .
this motor has had some work done but the previous owner couldnt remember what was done and the person that did the work isnt on the green side of the grass so I cant ask .
I dont know if the correct valve springs are installed as SRM seems to specify a 2 inch spring and mine are all over the place .
Sean
Title: Re: valves 1962 super rocket
Post by: chaterlea25 on 15.02. 2020 00:12
Hi Sean,
I always fit new springs on rebuilds

John
Title: Re: valves 1962 super rocket
Post by: sean on 15.02. 2020 00:30
me too just trying to find the right ones
Title: Re: valves 1962 super rocket
Post by: chaterlea25 on 15.02. 2020 12:51
Hi Sean,
Best to buy the lot from the likes of SRM who know their stuff

John