Archive for April, 2008

Jetting of a single Weber 40DCOE 2

Tuesday, April 22nd, 2008

Our Lotus has the basic configuration of a single Weber 40DCOE 2 on a Lotus alloy manifold. The performance of the basic engine is moderate, 66 HP at 4600 rev/min. The ports of our engine have been enlarged and the combustion chamber has been flowed moderately. Also, humps and edges in the inlet manifold have been smoothed out and the exhaust is 4-2-1. But most importantly, the engine is equipped with a fast road A2 cam. With the 0.06″ overbore our data show a power output of some 80 HP at 5200 rpm. Not a high reving engine but an engine with good midrange torque.  This power figure has been used for jetting of the Weber extrapolating from the unmodified engine. 

                                Basic 66 HP              Modified 80 HP

Camshaft                      Ford                                   A2

Choke                              26                                   28

Aux. venturi                     4.5                                  4.5

Main jet                          115                                 125

Air jet                             165                                 160

Emulsion tube                 F16                                 F16

Idle                                 45F9                              45F9

Pump jet                          65                                   65

With this setup up the car is lively and has no hesitation during acceleration.

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Smiths RVI tachometer reconditioning

Tuesday, April 15th, 2008

rvi-1400

The aquired RVI tachometer did not work, so a repair was necessary. The circuit board was in a fairly bad shape, but fortunately the board from the aquired RVP meter could be swapped. Apparently, Smiths used the same circuit boards for several models. The two transistors were unidentifiable (not the standard GETs), so they were exchanged with two AC 128 (NTE158 is difficult to source in Europe). The major capacitors and a few resistors were also changed and, voila, a working unit.

A note on bezels. The old, nice full-V bezels are no longer available for 3″ instruments, so care must be taken to save the old one which is not always possible. Apparently, these bezels are avaiable for 2″ and 4″ instruments so maybe there is just so much more demand for 3″. One can only hope that someone starts to produce them again, and this time slotted so assembly is easy.

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