The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: lefty on 30.01. 2009 17:34

Title: resleeving / is this barrel possible to fix?
Post by: lefty on 30.01. 2009 17:34
hi all,
i'm trying to rebuild my 61 a7 and among the problems is the barrels. looks like a conrod went and snapped off the bottom portion of the barrel. the liners i bought are 3/32" thick, and the original wall is 1/4".  so even with a new liner the damage will be apparent. photos follow.

what i need to know is this:
-are these too far gone to fix?
-will the missing piece of original barrel lessen the strength of the fitted sleeve?
-are sleeves available to replace the 1/4 barrel and still give a 66mm inner diameter?
 

thanks for your help

leif
Title: Re: resleeving / is this barrel possible to fix?
Post by: RichardL on 30.01. 2009 17:54
Lefty,

Others may have actual experience with this, but this is what I would, at least, investigate.

Get a piece of cast iron pipe (or other cast shape) that can be turned to the same inside and outside diameter as the bottom portion of the barrel. Cut away the bottom portion until you leave a clear, square-cut arc where the break once was. Cut the equivalent arc portion from your cast turning and have it professionally welded in place. Bore the now weld-laden cyclinder to fit the sleeve. Install sleeve. I think this is where a "oila!" might apply, unless I am completely wrong.

Richard L.
Title: Re: resleeving / is this barrel possible to fix?
Post by: beezalex on 30.01. 2009 19:55
My A10's been running on a similar bodge job since I've owned it for about 5000 miles and god knows how long before that.  When lining, the A10 barrels get paper thin down there and I'm supposing it broke out when it was sleeved.  The steel liners are a whole lot tougher than the cast iron they replace and there's really not much load on the skirt down there.

Then again, my A10 may blow up tomorrow, so who knows.....
Title: Re: resleeving / is this barrel possible to fix?
Post by: terryk on 31.01. 2009 03:58
It'll be right with the cast part brazed back in place as Richard says and new liners. It will last for years I have seen this lots of times in different engines I have dismantled and rebuilt. Even just liners without repairing the broken part have worked successfully, not that I have done it this way but I have seen it done.
Also just brazing up small cracks and rebore the cylinders without liners has been done successfully lots of times.

The best thing to do is repair the broken part as described then fit liners etc, good as new. Of course it should be done by an experienced engine reconditioner or the cylinders can be destroyed beyond repair.
Terry in OZ
Title: Re: resleeving / is this barrel possible to fix?
Post by: fido on 31.01. 2009 16:36
Alternatively:
http://cgi.ebay.co.uk/BSA-PLUNGER-STANDARD-BARRELS_W0QQitemZ300290016068QQcmdZViewItemQQimsxZ20090129?IMSfp=TL090129129001r11530

Not certain they would be correct for 1961 though. Did they do thick/thin flange on A7s or was that only A10s?
Title: Re: resleeving / is this barrel possible to fix?
Post by: trevinoz on 31.01. 2009 21:27
A7's stayed with thin flange but went to large fin as A10.
Trev.
Title: Re: resleeving / is this barrel possible to fix?
Post by: A10Boy on 01.02. 2009 20:06
The main thing is to stop cracking from that V in the break you've got, because that will track further up over the years if not treated. An engineer will drill a small hole at the end of the crack to stop it progressing. Then fit your sleeves as normal.

BTW, those Ebay barrels look like the early small fin type to me, no good for a 61.
Title: Re: resleeving / is this barrel possible to fix?
Post by: RichardL on 01.02. 2009 20:44
But, Andy, do you not think the replacement of the lost material is the best fix and best support/backing for the upcoming sleeve? The sleeve thickness at 3/32" seems lightweight for hanging in space without backing. If the fix is implemented there is no remaining deep "V" to worry about.

Richard L.
Title: Re: resleeving / is this barrel possible to fix?
Post by: olev on 02.02. 2009 02:44
Lefty,
I was in a similar situation a few of months ago.
I bought a 20 thou over size set of small fin A7 barrels complete with pistons and new rings from ebay in England.
Even allowing for the horrific postage costs, it cost me less than a resleeve from Serco.
I would suggest you check out the cost of a resleeve before you go much further. Unless you have the machinery yourself or a mate in the industry, or you're a lot wealthier than me, you will be better off waiting for a set to come to you.
cheers
Title: Re: resleeving / is this barrel possible to fix?
Post by: lefty on 02.02. 2009 18:48
hi all, thanks for the replies.

i just talked to a reputable machinist...and he wasn't at all happy fitting the thinner diameter sleeves in without first addressing the barrel's shortcomings. these parts are from a basketcase, which had an A10 head among the other surprises i'm yet to find. i don't have the missing pieces, so short of finding something comparable to cut and weld in place at a high cost, and this may still possibly make an issue of fitting where the flanges meet...it seems overly thick sleeves which replace the entirety of the flange are they only option they will come at. ouch!
may just watch for a while for one on ebay unless someone has one spare?

all the best
leif
Title: Re: resleeving / is this barrel possible to fix?
Post by: RichardL on 02.02. 2009 21:52
Lefty,

Understand, regarding the cost of machining and welding. I think I'm going to take to calling the broken part the "collar" for lack of a better term (until someone corrects me about five minutes after writing this). The problem that I think exists is that the thickness of the collar may be about all there is between the cylinder wall and open air at the base of the fins. Bore out that much and you could end up with a stack of fins laying on top of the base flange. Also, I would think the cost of boring out that much material would be equal to or more than spinning a tube to the right ID/OD and brazing or welding in place. Anyway, waiting to see if you can find one that needs less work may be the right choice. Though, you would probabaly be giving up starting out at standard bore with, maybe, three rebores possible. (I don't know if you could actually take 0.030" from the 0.094" wall for the 60-over rebore.) If you put yours up on Ebay, someone with his own shop (could even turn out to be one of our members) will buy it, fix it and use it.
Title: Re: resleeving / is this barrel possible to fix?
Post by: bsa-bill on 02.02. 2009 22:22
Hi Manosound - sorry I could not resist  *computer*

Collar - would be nearer the head, down there it's got to be skirt *lol*

All the best - Bill
Title: Re: resleeving / is this barrel possible to fix?
Post by: RichardL on 02.02. 2009 22:36
Yup! Agree. Skirt it is. I've always liked them better anyway.
Title: Re: resleeving / is this barrel possible to fix?
Post by: fido on 03.02. 2009 13:16
Not sure if this is what manosound means but you could have liners machined that were the thickness of the sleeve at the bottom, exposed section and a smaller diameter in the section that  goes inside the casting.
Title: Re: resleeving / is this barrel possible to fix?
Post by: trevinoz on 04.02. 2009 23:04
Good thinking ,Fido. I have had that done to the set on my '55 Flash. No trouble yet.
I would hate to think what it would cost to do it though.
I had a Mate do mine in exchange for tasks I could do for him and only cost was the cast iron.
  Trev.
Title: Re: resleeving / is this barrel possible to fix?
Post by: Richard on 05.02. 2009 22:26
It must be about time to do some more tasks for your mate.
Good luck with the resleeving
Richard