5 replies to this topic

[JetBLICK]

I got a friend called Steve, we're both well into short stroke engines... and with all this talk of short strokes recently, he's let me put this up...

The engine centered around a south african 1071 crank. There are good reasons for using this over an English 1071 's' en40b crank. Firstly it fits into a non-s block easier, and non-s blocks are a damn sight cheaper. Also they have standard size big ends, rather than the smaller 's' type. Another benefit is the stroke of these cranks is closer to 70mm rather than 68mm of the British ones, this means that although the engine will be short stroke, it will also be closer to square, meaning more torque. But the main reason above all this is the price. He bought this crank on a standard grind for the same price you'd pay for an 's' crank on a 40/40 grind.

The crank was then modified, its been backdrilled and wedged to loose weight, crossdrilled for improved lubrication and heat treated to reduce wear.

The block being used is a pre A+ 1300 innocenti block, which has been offset bored to accommodate the pistons and fitted with a center main strap

The pistons are 73.5mm featherlight forged Omegas they're fully floating, and have a smaller 18mm gudgeon pin to save more weight.

Conrods are from Specialist components and have been modified with a bigger bush in the little end for the smaller gudeon pin.

The cam being used is a Piper BP300 and the rockers are 1.3 ratio roller rockers.

The head has been done for the engine, designed for trackday use and to flow with a weber. Its got 36/31mm valves with bronze valve guides and waisted stem inlets.

The engine will be running a dizzy so the compression is being kept to a sensible 11-1

Its not finished yet, Steve rekons he'll have it done and in the car by the new year, and run in and ready to race soon after. He also has no idea on the potential power, we've made educated guesses, but he doesnt want to speculate.

Photos

Ta, Dan

[mini93]

looks good and very clean! love the rods also

where would you enquire about finding a SA 1071 crank out of interest?

[JetBLICK]

he wont even tell me He got it off a friend or something, i dunno how or who tho.

[mini93]

aah well thats just a pain in the...

never mind, ill have to find alternative means if i choose to go that route

[1987_ParkLane]

Sounds good, any pics?

[JetBLICK]

Thers a link to the pics at the bottom of the post. His flickr account is set up so that you cant link the photos direct tho im afraid