Hints and Tips - Austin Seven Blocks

Pete Bishop wrote:
> I have a 1933 ish Ruby engine and a bare 1930 ish coil ignition
> crankcase plus flywheel. Do you know if it is possible to swap the block
> and internals from the Ruby engine into the earlier crankcase to build a
> vintage spec engine?
>
> That way I will have a VSSC acceptable "spare" engine when the first one
> does let go.

Pete

Blocks are all interchangeable. Early ones last better, late ones will bore out further.

Splash feed cranks are in three sizes. Early vintage were tiddly 1-1/8th big ends until about 1928. The common size is 1-5/16in. Some sports engines had 1-1/2in both splash and pressure feed. The only mod to fit a 1-5/16 into an 1-1/8 is to drill an oil drain hole for rear main. The early cranks had a tin cover and felt to keep the oil in the back of the engine while later ones have an oil thrower and scroll.

In 1937 the three bearing engines came in. A two bearing crank will fit a three bearing crankcase but you need to take an angle grinder to the inside to remove a bit of the bearing housing. Desperate measures but the three bearing crankcases are cheap cheap cheap. Some of the 750 club racers prefer the three bearing crankcase as it is stiffer and stronger.

The book to get for this type of knowledge is the 750MC 'green book' which is A5 and spiral bound with reprints from their news letter from the days when such mods were necessary for cheap day to day transport and/or keeping a race car fed with engines.

My specialist-du-jour is Tim Myall who runs Pigsty Engineering. He helped with tints and hips and repaired my front bearing housing same day for me. The Pigsty is on 01342-870-988. He's modifying the best of my blocks to 'full race' spec for the next engine with very large inlets and opened out ports. My current block wasn't suitable for this treatment as an exhaust stud hole had been extended into a water passage and blocked with a bit of solder.

David
David Laver


Home | Hints & Tips | Suppliers | Engineering Data | Links | Events | For Sale | Gallery | Books | Videos | About Us