Hi. I'm still looking for a set of barrels for my 1968 A65 engine. The parts book says that the part number starts with '68' but the only A65 barrels I can find (on eBay or elsewhere) have a part number that starts with '71'. I'm guessing that the barrels with a '71' number are for engines made after 1970 . I've been told (rightly or wrongly) that two of the bolt holes were spaced differently on barrels made after 1970 so they won't fit my engine. Any confirmation or denial of that would be useful to know.
Thanks
Regards
Tony
do you mean the part numbers on the castings?
this will be the casting number, the complete painted and machined barrels will be a different number.
Hi. Thanks for your reply. What I'm trying to establish is whether a barrel that has the number 71-1033 stamped into it will fit onto a 1968 crankcase and cylinder head, given the differences in bolt diameters (5/16 vs 3/8) and bolt spacing. I'm new to BSAs so getting the correct barrel is proving challenging as my knowledge is limited to what I can glean from the internet.
Thanks
Tony
my Roy Bacon twins book is at my unit.
maybe someone has one to hand that can look in the back to check part numbers, might possibly help.
the only other check would be checking individual parts books to see if any differences.
1968 68-886 Lightning Spitfire Thunderbolt Firebird or 68-888 Royal Star (500)
1967 68-43 L S T H 68-48 for R W (500)
1966 same
1964 same
1969 as 1968
1970 71-1195 L T F 71-1196 R (500)
seems to suggest 68 and 69 the same, 64-67 same and 70-71 same, but its not unknown for changes to part numbers , im finding it with 69 parts at the moment, some Triumph numbering.
maybe just bolt hole diameters, unlike the Triumphs where they went from 8 stud to 9 stud barrels and heads.
71 1033 is a later barrel.
This one is from a 1971 OIF Lightning.
Thanks Julian.
Regards
Tony
The later barrels have bigger crankcase stud mounting holes, later barrels will fit earlier crankcases but earlier barrels would need to be drilled to fit later crankcases.
In other words the later barrels will fit but you might have to put the later studs on your crankcases which is a mod that can be done.
;)
derek
:) :) :) :)
I seem to recall that there were collars available to pet on the earlier studs instead of needing to 're stud' with the later size. ????
Mike 8) 8) 8) 8)
Thanks guys. I was worried about using a later barrel for three reasons:
1. Would the earlier (1968) cam followers that I've already bought work in the later barrel?
2. Making sure that the later barrel with 3/8 holes wouldn't move around on the 5/16 studs during engine use. If sleeves are available they'll only have a 1/32 wall thickness but I guess they'll be supported by the barrel stud hole walls so should be ok. The only problem now is where to get them - I'll get onto Google.
3. I've read that the two front stud holes in the barrels are in a slightly different pattern on the later barrels and that to use a later barrel on an early crankcase, you have to get the front two holes elongated - if that's true, it sounds like a major engine job and might not give a good fixing for the nut as it won't be supported by the barrel over its whole circumference.
Thanks again
Tony
the "spacers" hollow dowels are a standard feature on many Japanese bikes, I would not worry about fitting them, I have made some on a lathe where damaged on removal.
My engine is from 63, barrel 68-44. 5/16 studs and the 2 backbolts also 5/16.
The head is a lightning 70 head with all 3/8 headbolts. The 2 back are 3/8 bolts with altered thread 5/16.
Gr gup
If you try and fit a late barrel to an earlier bike, the 2x studs front and centre are spaced differently.
There seems to be a bit of a glut of OIF barrels on eBay at the moment, but they are quite rare compared to an earlier type. 68-44 is quite common, though often need the rear studs for the head changing to 3/8" which isn't difficult.
Be patient. There will be a few early types on the market before you know it.
Hi Allan (and everyone who replied). Thanks for your thoughts and comments. Allan, I wish I shared your optimism about the correct barrels turning up on eBay soon. I've been looking for about four months and not seen anything apart from barrels with badly broken fins and/or wrecked bore skirts. However, I'll keep looking!
Regards
Tony
I think its very doable to use later barrels on earlier cases, here is an earlier post that explains
https://www.bsaownersclub.co.uk/bsaoc_forum/index.php?topic=11263.0
If you cant get earlier barrels its certainly a route i would go down.
;)
or get a Triumph i have been working on a nice 1965 TR6 and you can get all the parts you need.
Try these.
It does have one broken fin. But it will be hidden by the down tube or you could have it replaced.
Hi Allan. Have sent you a personal message. Tony
The barrells part number for a 1968 is 68-0886 for a 1967 68-43 as far as I can see there are lots of varieties so be sure you have the right ones. I am nearly completing a build on a 1968 Thunderbolt and have had to be very carefull when ordering parts good luck .
TJWood.
In answer to your question. I think they might have sold as I can no longer find them.
Thunderbolt and lightfoot: I have used 68-44 cast barrels on my A65, they are more common than the 68-886 ones you mention. The only thing you need to do is increase the size of the two rear stud holes from 5/16 BSF to 3/8 BSF.
I used a drill press when I did mine, set the barrel up so it is dead level and set the tap in the chuck, and manually wind it in. If you use a taper
Tap you could get away with just using the taper as a reamer and clean out the smaller threads.
Hi Thunderbolt and Allan. All of the barrel studs on my crankcase are 5/16. It sounds like the 68-44 barrels have some 3/8 holes for the barrel studs, so they wouldn't work for me. It sounds like I'm going to have to try and find some very early barrels that are the 68-886 type - I won't hold my breath for a quick result!
Regards
Tony
Hi,
SRM do "3/8 UNC TAPS & Drill kit for convert base studs to 3/8 UNC". There is no mention of re-centring any studs.
I would suggest ringing them up and asking what using the later barrels entails.
Dave.
Hi Tj , Barrels do come up quite often but lots have fin damage Try somewhere like Owens wrexham chaps name is Eldon I believe they are very good I do have a friend who might have a set I will ask him good hunting .
fin damage!!!
are there no good welders locally?
we used to have a ex foundry welder, always picking up pieces of 4mm thick cast material and welding new fins on, once dressed off and painted, who would know.
wouldnt stop me buying a barrel with a damaged fin. Ive even known people buy a second barrel and breaking the fins off using as spares.
Quote from: Tjwood on 09 Dec, 2023, 22:19
Hi Thunderbolt and Allan. All of the barrel studs on my crankcase are 5/16. It sounds like the 68-44 barrels have some 3/8 holes for the barrel studs, so they wouldn't work for me. It sounds like I'm going to have to try and find some very early barrels that are the 68-886 type - I won't hold my breath for a quick result!
Regards
Tony
Hi Tony, I think you are getting confused, or I have explained it poorly.
Any barrel with the 68-xxxx has 5/16 barrel to crank case studs.
The 68-44 was the first form of that barrel, it had 3/8" head to barrel threaded holes (BSF) however the rear 2 behind the pushrod tunnel were 5/16".
Around 1966 +/-1 year. The barrel was changed to the 68-886 you mention was the later and the last version of that barrel used right up until 1970 production. The 68-886 barrel had 3/8" BSF headbolt threads all around..
The good thing is, the 68-44 barrels can easily be opened up to accept the larger 3/8" head bolt threads which the 68-886 barrel has.
Any barrel (A50 or A65) which starts with 71-xxxx has the 3/8" barrel to crank case holes and has the two front and center bolts in a different position.
I have used 2x 68-44 barrels now which i have converted the rear stud holes to 3/8"... Very easy to do and your also working with new threads.
Hi Allan. Thanks very much for that excellent
explanation. My fault for not understanding - this is my first BSA rebuild and it looks like I might have stumbled into a total minefield as far as parts compatibility goes! I've plenty of experience rebuilding mid-60s Triumphs and Nortons, but the A65 is a complete unknown. Thanks again for your help.
Regards
Tony
No worries. Hope you get sorted.
set on facebook 5/16 stud holes £275
;)
I hope they have. A good bore and still on standard for that amount.
(https://scontent-lhr8-1.xx.fbcdn.net/v/t45.5328-4/333434306_5934108963291080_7760316786824651508_n.jpg?stp=dst-jpg_s960x960&_nc_cat=108&ccb=1-7&_nc_sid=247b10&_nc_ohc=N4DIZoqwnX0AX-2jFSW&_nc_ht=scontent-lhr8-1.xx&oh=00_AfA5WiGiPJ0SGKMCTRTItAU0G5Yz3YHdKjxjIFH958eyFA&oe=657E1455)
No idea what they will be like.
I'd leave them where they are. The bore is offset and has little gasket seal near the rear studs compared to the front ones. You could have them sleeved to bring them right again. But it makes them an expensive barrel.
Derek, thanks for posting up details and photo of that barrel. It looks a bit 'tired' and appears to be on +60 already so little chance of improving the bores without sleeping. That would make them a lot more expensive than I want to pay so I'll keep looking, but thank you again.
Allan, well spotted re the narrow gasket face on those two rear bolt holes - I've never seen bores get that close to fixing holes on any barrels I've ever looked at.
Regards
Tony
Tony, barrel here.
https://www.ebay.co.uk/itm/134855696889?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=S0Z9ets9TTS&sssrc=4429486&ssuid=nWtb5UlMTYW&var=&widget_ver=artemis&media=COPY
Looks to be on about +040
It's the pre 1970 type, which is noticeable because it doesn't have the cut outs in the lower fins to access the later 12pt nuts with a ring spanner. So it has the full lower fin.
Thanks Allan. I'll have a go at them.
Regards
Tony
Burton Bike bits have a set. Give Carolyne a call.