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Stupendous 750

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The modified Austin Seven engine

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Many of the special parts offered by SPEEDEX were to tune up the engine to develop more power. Engines hold a distinct interest for car enthusiasts, they all like looking under the bonnet to ‘see what it’s got’ and modifications to other parts of the car although useful are less visual in appeal. This is a picture of my engine that I’ve built up and incorporates many SPEEDEX parts or equivalents. The sharp eyed ones amongst you will notice it’s a three bearing engine and not quite finished when the shot was taken, some of the parts are only loosely held on!

This is a negative shot of the same picture labelled to show the special parts. Most of these are described separately on the SPEEDEX parts page.

Aluminium high compression head with improved plug location, special rear facing water outlet

(Not visible) large inlet valves, opened out ports, double valve springs, relieved block and racing pistons

Aluminium tappet chest cover

Oil system piped out to a full flow oil filter

Square headed bolt replaced by normal bolt tapped right into the bearing bush to prevent movement and oil leaks

Blanked off ‘nose’ piece—no starting handle

Vee pulley to drive water pump

(Not visible) reground high lift extended overlap camshaft with flattened followers

Deep finned aluminium sump with extended oil pump pick up pipe. Over bored oil pump.

Blanked off petrol pump flange

Free flow four into one large bore exhaust manifold

Lightened flywheel and clutch assembly

Twin 1 1/8” SU carburettors on cast aluminium inlet manifolds

A few more pictures of some of the interesting parts

Lightened flywheel

Three bearing engines can easily incorporate an extra block holding down stud. The second centre bearing stud has a block stud fitted with the block being drilled. Note also the cut down tappet guides to give clearance with a modified camshaft and the double valve springs.

Large inlet valve and ‘relieved’ block. The edge of the block going into the top of the cylinder is chamfered down to smooth the gas flow. Only make it as wide as your combustion chamber and gasket and don’t go too far down the bore—the top piston ring shouldn’t be exposed. Oversize inlet valves are available from John Barlow, make sure they don’t get too close to the hot exhaust seat, 1 1/8” to 1 5/32” is about as big as you should need to go with a standard 1” exhaust valve.