55 v 57 A7 Big Fin Barrell

[AlP]

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

[Beezageezauk]

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.

[AlP]

Thanks for that.

[duTch]

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

[trevinoz]

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.