01-03-2018, 04:29 PM
My 1950's Hepolite catalogue confirms that the Austin Big Seven 900cc 1937 to 1939 and the New Eight 1939 onwards used the same engine and therefore the same Hepolite RS7665 pistons. However Big Seven pistons differ from those in the earlier model Austin Sevens 747cc 1923 to 1939 which are Hepolite RS11063.
The differences are as follows:
Austin Big Seven & New Eight: Bore: 2.235", Compression Height: 1.25", Length: 2.5"
Austin Seven: Bore: 2.20", Compression Height: 7/8", Length: 1.13/16"
Zeto will need to confirm if his are the earlier 747cc pistons (which I think they probably are) or Big Seven pistons.
The differences are as follows:
Austin Big Seven & New Eight: Bore: 2.235", Compression Height: 1.25", Length: 2.5"
Austin Seven: Bore: 2.20", Compression Height: 7/8", Length: 1.13/16"
Zeto will need to confirm if his are the earlier 747cc pistons (which I think they probably are) or Big Seven pistons.