912 Manual


The 912 manual is a slim edition that supplements the 911 manual for the same period. It covers the major differences between the two models.

Engine Description

912_fig_1 The engine shown is for a 1965-1966 SWB car and has the German heating system. There is no smog equipment on the car other than crank case ventilation from the oil filler can to the right hand head.

In late 1966 the motor mount changed from the flat plate shown to a U-shaped channel with 4 rubber motor mounts. ...More
912_fig_2 Here we see a diagram of the engine showing how the cylinders are numbered. One additional piece of information is the cylinder firing order: 1-4-3-2 ...More
912_fig_3 The figure shows a cutaway view of the engine with major items identified. ...More
912_fig_5 The bottom view again shows the German edition of the 912 with different heater components including modified heat exchangers and muffler. This version was used for Sweden and Germany. The rest of the world recieved 'flapper boxes' patterned after the VW Beetle of the period. Notice also that the mounting system for the exhaust system is different with what appears to be connections to the third piece of the engine case. ...More
912_fig_6 We often refer to the timing gear cover as the 'third piece'. The manual description is interesting because there it includes assembly instructions which seem out of place in this section of the manual. ...More
912_fig_7 Here we see the crankshaft and connecting rods.

The four connecting rods ride on the plain-bearing crankshaft in lead-bronze bearing inserts. All connecting rods have bronze piston pin bushings. All crankshaft journals are soft nitrided. ...More
912_fig_8 The light-alloy pistons in the Type 912 engine have 3 piston rings each, the lowest ring being the oil scraper. The piston pins float in the connecting rod bushings; they are contained within the pistons through the use of circlips.
912_fig_9 A big bore kit has larger diameter pistons, from 83.5mm to 86mm. The cylinder description is, of course, for the stock cylinder which are not suitable to be bored out to accept the larger diameter pistons. Cast iron cylinders used for the 356C engines are often used for this purpose. ...More
912_fig_10 The clylinder heads are symetrical left and right. The combustion chamber needs to be modified for the narrower sealing surface of big bore cylinders. ...More
912_fig_11 The 3-journal camshaft rides on the base metal of the crankcase. Camshaft drive is through helical gears; the timing gear is of light alloy. Valve timing is effected through cams, valve lifters, push rods, and rocker arms. Each cam alternately actuates one valve of two opposing cylinders. The exhaust valves are cased with high-grade chrome-nickel steel. ...More
912_fig_12 The engine is cooled by an air blower. The blower impeller is situated on the extended generator shaft which is driven by the crankshaft over a V-belt. The blower draws cooling air through an intake in the blower housing and forces it over the heavily finned cylinders and cylinders heads. The cooling air is guided by deflector baffles.
912_fig_13 The engine oil supply is in the bottom of the case, normal with wet sump lubrication systems and unlike the 911.

Engine lubrication is effected through a forced feed system and includes an oil cooling provision. ...More
912_fig_14 The stock oil cooler is made of steel and is associated with cracks in the case. An aluminum replacement is available which has better head transfer characteristicsand is lighter weight, putting less stress on the case.

The oil cooler is mounted on the crankcase in the stream of cooling air forced through by the cooling blower. The oil cooler is so inserted into the oil circuit that the oil pumped by the oil pump must pass through the oil cooler before it reaches the points of lubrication. ...More
912_fig_15 There are two electrical sending units shown in the diagram. The vertical one is the pressure sender and the horizontal one behind it is the temperature sender. It is not uncommon for these to fail and to leak oil. ...More
Last modified: Mon, 17 Jan 2005


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