The BSA A7-A10 Forum

Bikes, Pictures, Stories & more => Introductions, Stories & Pictures => Topic started by: lefty leif on 05.05. 2014 23:34

Title: 1962 A7 project
Post by: lefty leif on 05.05. 2014 23:34
adm edit: split \ renamed \ moved from "A7 & A10 Engine"

so, as promised, here is a picture of the 1962 A7 project.  It was bought as a basket case - tarted up a bit to make it look better than it really was.  There was caked in dirt under the paint in more than a few joints, a hole in the center bung of the gas tank, a few areas on the frame that needed attention etc etc. The kind of stuff that is hard to notice in a dark shed when you're excited and the price isn't terribly unrealistic!  that said, it's been a long road already, but things are slowly coming together.  As is my 1950 rigid C11 project which looked far worse than the A7 when purchased in 20 odd boxes, but ended up being considerably less of a pain in the butt to put back to a decent state. 

I was told the A7 had been traded to the previous owner by a fisherman for some work he had done, and by the look of the crank it wouldn't suprise me if it had spent some time as a boat anchor it is so rust pitted.  Surprisingly, most other items looked really decent in there.  I suspect it got a fair bit of water down inside the cases and was left sitting on it's side for ages and just ate away at the splines and crank cheeks while it sat.

once I finish truing and aligning the wheels and rear sprockets, I can get the fenders on and start with the sorting of the engine.  getting a new crank, or the extensive work in fixing the old one, was the first major hurdle and thanks to Mark at British Cycle Supply he got me one of the ones they bought from the old domiracer stock - and he has more should anyone else find themselves in a similar state.

so to go - the cases need a little weld for a small crack, a rebore on the barrels, and likely lots of work on the head, so don't expect progress to be even remotely fast...

There will be many questions as the days go by - so thanks in advance for all the help you lot can give.


Title: Re: 1962 A7 project
Post by: lefty leif on 05.05. 2014 23:35
and the c11
Title: Re: 1962 A7 project
Post by: a10gf on 06.05. 2014 00:05
Looks like it's evolving nicely! Will be ready for summer? And that's a clean workshop!! Clean as a Chef's kitchen *smile*
Title: Re: 1962 A7 project
Post by: lefty leif on 11.01. 2019 04:34
Well, two kids later, moving to a new house and a change of jobs, and i'm finally getting a little time to pick away at the bikes again!  they look little different so far, but i have been collecting needed parts here and there, and will make more of a point to pick up the pieces again, and hopefully, the pace.

Starting at the bottom end...  I have two sets of conrods, one original set that is hopefully salvageable, and a second that i'm very curious about.

They appear to have been never used and an oddity at that. no pips for the shell bearing to locate into, and the massively oversize and offset small end bushes.  i expected this would be to lower compression or to be able to use a higher crowned piston instead of a flat top style, but both seem to be 6" on center, and with the added weight at the top end, not sure why they would have chosen this route unless they are actually for an A10.  I need to measure the big end as well as i think it was too large to use with my crank.  But if they can be sold to finance the machining work on the barrels and crank bushing etc, then that's fine too.

Any ideas on the casting numbers?  R3Z1Z instead of R1R mean anything to anyone?

Title: Re: 1962 A7 project
Post by: Klaus on 11.01. 2019 08:28
Hi lefty,

Conrods for A7 are allways small journal and 6 inch, the small bush is I gues 11/16 inch
A10 small jounal is 6.5 inch long and a 3/4 inch smal end.

Expekt the A7 Daytona with 6 inch big journal.

Dont know the partnumber.

cheers Klaus
Title: Re: 1962 A7 project
Post by: Swarfcut on 11.01. 2019 08:46
G'Day Lefty.

   A7 cranks all have the same so called small journal big end size.  Early A10s also use the same small journal size, changes over to the big journal A10 crank were phased in from the mid 1950's.

   A7 rods are stamped 67 391,  Small journal A10  67 270, Big Journal A10  67 1160

 By chance I have a few rods lying around to measure.

  Small end of the rod measured adjacent to the forging flash  A7 measures 32.5mm,  A10 measures 35mm, slightly larger to accommodate the bigger diameter  A10 piston pin.

  A crude measure of the length between the eyes, the indented centre of the rod, the bit with the numbers on, measures A7  rod 110mm,  A10 rod 120mm

  This should enable you to identify how they started out originally.

  I have always thought the R3Z1Z etc numbers are to identify the die that forged the rod, so will vary even though the forging number identifying the rod stays the same.

    The overall length of my standard small journal A7 rod is 203mm,  A10 rod is 215mm

  Reckon they are unique, but alas not rods that you could use with confidence. Maybe I am a bit cautious!

Title: Re: 1962 A7 project
Post by: muskrat on 11.01. 2019 08:58
G'day Lefty.
Been a while, sometimes life gets in the road. Good to see your back on track.
I agree with Swarfy, use the R3's for shed ornaments.
An easy way to check the A7 rods is to hold them together at the big end and look at the gap at the little end. Then turn one around and observe the gap, then turn the other. Gaps should remain the same. Twist is a little harder to see. Best take them to an engine re-conditioners to check.
Title: Re: 1962 A7 project
Post by: Swarfcut on 11.01. 2019 10:02
Just had a closer look.....appears to be an A7 rod.... 67 391. I can only guess that back in the day the big end was damaged so badly, and with no spare available, the cap and rod had to be reclaimed in the usual way, enough to remove the tabs.  The small end bushing is a real mystery. See how the overall rod length compares with my measurement. Maybe a factory back door unfinished part, modified for some exotic project.