The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: AlP on 24.05. 2012 06:43

Title: 55 v 57 A7 Big Fin Barrell
Post by: AlP on 24.05. 2012 06:43

Can anyone tell me if there is any physical differences between the 1955 and 1957 big fin barrel for A7's?

Title: Re: 55 v 57 A7 Big Fin Barrell
Post by: Beezageezauk on 24.05. 2012 10:05

Hi AIP,

On checking the part numbers from the 1956/57 parts list and comparing them with the 1960-on parts list the part numbers are the same (67-1070) for the A7 barrels.

The Roy Bacon "Twin" Restoration Book also confirms this and shows that this part number began in 1954 and went through to 1962 when the A7 was discontinued.

So, as the part numbers are the same for the 1955 and 1957 models the barrels should be identical.

Beezageezauk.

Title: Re: 55 v 57 A7 Big Fin Barrell
Post by: AlP on 24.05. 2012 10:25

Thanks for that.

Title: Re: 55 v 57 A7 Big Fin Barrell
Post by: duTch on 25.05. 2012 00:44

I may be wrong, but isn't there a big fin/thin flange barrel?, and if so is it A7 or A10 or both?

Title: Re: 55 v 57 A7 Big Fin Barrell
Post by: trevinoz on 25.05. 2012 00:52

A7 were always thin flange, regardless of whether they were big fin or small fin.
A10 small fin barrels are thin flange as were the Flash barrels up to and including 1957.
Rocket barrels, according to the parts book, were initially thin flange. Thick from 1956.

Trev.