The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: scotty on 25.02. 2010 21:32

Title: A10 thick flange barrel
Post by: scotty on 25.02. 2010 21:32
Greetings all,

I just purchased a very useable A10 thick flanged cylinder block for a future build and it has one notch in the top fin front L/H side.
I'm assuming that the notch has something to do with the exhaust pipe collar clearance. It's a very clean/uniform notch with clean edges.
If its a clearance notch shouldn't there be a notch on the RH side as well ?

No's on the block are
67-1210
Y2
567020

Has anyone come across a one notch top fin like this or am I looking at a broken fin ?

My work in progress 55 A10 iron head engine has notches in the head but not on its thin flanged cylinder block.

Any wisdom greatly appreciated

cheers

Scotty

Title: Re: A10 thick flange barrel
Post by: octane on 25.02. 2010 22:19
Greetings all,

I just purchased a very useable A10 thick flanged cylinder block for a future build and it has one notch in the top fin front L/H side.
I'm assuming that the notch has something to do with the exhaust pipe collar clearance. It's a very clean/uniform notch with clean edges.
If its a clearance notch shouldn't there be a notch on the RH side as well


Yep!,  it's really weird that it's only on one side that you have it

(http://i184.photobucket.com/albums/x214/octane98/050708.jpg)

Quote
Any wisdom greatly appreciated

Sorry; I can not offer any wisdom


.-)

.
Title: Re: A10 thick flange barrel
Post by: muskrat on 26.02. 2010 06:06
Looks like a broken fin has been repaired.
Cheers
Title: Re: A10 thick flange barrel
Post by: scotty on 26.02. 2010 17:20
Thanks for taking the time to respond.

Octane:
Thanks for posting the pic. It's a great help.

Muskrat:
Thanks for the response. I'm going to clean off the paint this weekend and look for evidence of repairs and examine if it's possible to notch it out to match the other side.

Seeing Octanes bench I was wondering if the thick flanged barrels used with A10 alloy heads are the same as those used with A10 iron heads or were they different ?

Thanks again for the replies !

cheers  *smiley4*

Scotty




Title: Re: A10 thick flange barrel
Post by: MG on 26.02. 2010 17:24
Quote
Seeing Octanes bench I was wondering if the thick flanged barrels used with A10 alloy heads are the same as those used with A10 iron heads or were they different ?

They are all the same.
Title: Re: A10 thick flange barrel
Post by: scotty on 26.02. 2010 17:47
Thanks MG  *smile*
Title: Re: A10 thick flange barrel
Post by: groily on 26.02. 2010 17:50
Surprises me there are that many thin-flange barrels still around . . . thought we destroyed them all in our carefree youth . . . Must have missed a few. I have someone else's A in the shed at the moment for what people euphemistically call 'recommissioning', and lo and behold, a thin flanger still going strong. On A7 cases mind you, so it might be a real survivor. (Actually, it's turned out to be quite sweet  - testimony to the basic ruggedness of the design, as it hadn't run for years till this week. But . . . who knows what's in there . . . just lurking . . . like the calm before the storm probably.)
Title: Re: A10 thick flange barrel
Post by: LJ. on 26.02. 2010 19:21
Amazes me how often you see early A7 barrels crop up on ebay, some there now for about £35 but no one wants them.
Title: Re: A10 thick flange barrel
Post by: MG on 26.02. 2010 19:37
Speaking of barrels:
Are there any news about the SRM thick flange barrels? The last information I got about a year ago was that they had problems with the casting, which I find, let's say, ehm, rather "remarkable", considering the fact that it worked pretty well more than 50 years ago.  *doh*  *dunno*
Soon afterwards all information on the website disappeared without any further comment.

Maybe you guys in the UK got some more "insider knowledge"?


Who knows, maybe they would like to get rid of the casting moulds, I definitely could use them  *smile*
Title: Re: A10 thick flange barrel
Post by: muskrat on 26.02. 2010 19:40
G'day Scotty, should be easy enough. Make a cardboard template and flip over to mark the other side. Then grind out with a dremel.
LG, most people wanted the 650. Next rebuild on the '51 A7 it will grow to A10.
cheers
Title: Re: A10 thick flange barrel
Post by: scotty on 26.02. 2010 19:51
thanks again Muskrat..sounds like a plan !



cheers

Scotty
Title: Re: A10 thick flange barrel
Post by: A10Boy on 27.02. 2010 19:10
Scotty, unless the old eyesight has finally failed, it looks to me like your work in progress has a set of small fin barrels with a large fin head, is that the case?

BTW, I got a set of old long stroke a7 barrels and NOS pistons if anyone ever needs any.

Title: Re: A10 thick flange barrel
Post by: scotty on 27.02. 2010 20:00
Hi Andy

thanks for the 20/20 vision observation...it does look like the head fins have a considerably larger footprint than that of the cylinder block.

Here's a couple of pics of the bitsa in mock up with thin flange barrel and iron head before I sent everything away to me machined.

We're there considerable differences with the cast iron heads fitted to S/A A10's over the years ?

When I spotted the thick flange barrels with pistons and rings in some local classifieds at a sensible price I snapped them up PDQ with the idea of doing , one day, a RGS replica. However...as I continue to learn more from this great forum ..I am now toying with the idea of putting the thick flange barrel on the work in progress instead.

decisions...decisions  *smiley4*

cheers

scotty
Title: Re: A10 thick flange barrel
Post by: trevinoz on 27.02. 2010 20:31
Scotty,
                  Use the thick flange barrels on your engine and keep the small fin set as the basis of a plunger project.
Should keep you occupied finding the rest of the bike!
  Trev.
Title: Re: A10 thick flange barrel
Post by: scotty on 28.02. 2010 19:07
Trev,

Yeh...mulled it over with a few cold ones.....thick flange will go on the current A10 replacing the thin flange.
Both thick & thin barrels are at +40 so should be good to swap and I guess I'll fit a new set of longer barrel/crankcase studs for the thick flange
A bit of work to un do but no big deal on the grand scheme of things seeing as it's taken me over 2yrs to get this far  *eek*

as far as collecting parts for a plunger I rather thought it would be nice for me to die of old age as I would surely meet a premature demise if "she who must be obeyed" suspects yet another vintage bike build on my radar screen  ;)


Thanks again to all that pitched in to this thread  *smiley4*

Cheers

Scotty
Title: Re: A10 thick flange barrel
Post by: muskrat on 28.02. 2010 19:58
Looking good Scotty, wise move with the barrels. All future projects top secret, say they belong to a friend.
Cheers
Title: Re: A10 thick flange barrel
Post by: 1660bob on 28.02. 2010 20:24
MG- I made some enquiries with SRM recently (well 4 months ago) regarding A10 barrels,their website lists them, but the relevant page is obscured by a large "NOT IN PRODUCTION" sign.I spoke to one of the staff there as I like many, could also use a decent set .The chap at SRM explained that problems with porous castings are the issue, as he said "BSA had their own foundry and any rejected barrels went straight back in the melting pot to be re-cast", I assume from this that casting iron has a high rejection rate due to porosity, and thus small production runs would be too costly..... They have done it before though, (according to the SRM web page under "Special Products") "using the original BSA" moulds ?, so perhaps they will yet make some, we live in hope.....Bob
Title: Re: A10 thick flange barrel
Post by: MG on 28.02. 2010 20:36
Bob, thanks for the info. Let's hope the best. Fortunately I have found a decent set on ebay in the US that I'm using on my A10 now.
Title: Re: A10 thick flange barrel
Post by: BSA_54A10 on 01.03. 2010 21:27
One little thing that oft gets overlooked is when you "improve" the bike by fitting the thick fin barrels your original pipes will need a little tweaking to compensate for the exhaust ports now being a little higher.
Title: Re: A10 thick flange barrel
Post by: MG on 02.03. 2010 07:36
Quote
One little thing that oft gets overlooked is when you "improve" the bike by fitting the thick fin barrels your original pipes will need a little tweaking to compensate for the exhaust ports now being a little higher.

I don't think so, the overall height of the barrels is the same, just the flange is bit thicker. Otherwise using the thick flange barrel would lower the compression ratio, too.
Title: Re: A10 thick flange barrel
Post by: trevinoz on 02.03. 2010 20:46
I agree with MG.
                               Trev.