A65 barrels

[Tjwood]

Hi Allan. Have sent you a personal message. Tony

[thunderboltandlightfoot]

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 .

[Allan G]

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.

[Tjwood]

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

[DAVE BRADY]

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.

[thunderboltandlightfoot]

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 .

[chaz]

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.

[Allan G]

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.

[Tjwood]

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

[Allan G]

No worries. Hope you get sorted.

[DerekAnderson8]

set on facebook 5/16 stud holes £275

[Allan G]

I hope they have. A good bore and still on standard for that amount.

[DerekAnderson8]

No idea what they will be like.

[Allan G]

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.

[Tjwood]

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