mechanical tach drive

[flyguyeddy]

im curious about something i saw while looking through the limbach DE parts catalog. apparently they have two types of mechanical tachometer drives, one comes out of the distributor hole with an angle drive, and another uses the oil pump gears to drive a cable. i see that the porsche 356 engines had such a beast, but they seem to be wildly expensive. i have heard of a VDO unit made for the industrial engines, but have not had much luck finding them. is there such a thing available anywhere? what size is the vdo pump? what size is the 356 pump? it appears that the 356 uses a 3 piece crankcase with a front cover that has the pump built in to it. can an aftermarket t1 pump rear piece be used with those units? dished or flat cam required to use 356 pump?

thank you for any answers you can provide.

[bugguy1967]

The 356's pump's gauge only went to 4000 rpm. You'd have to fashion something up.

If you're clever enough, maybe go right off the crank via a modified speedo cable or something?
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[flyguyeddy]

The engine I desire to use this on wont breach 3600rpm pretty much ever.

I sadly dont have access to the crank for this application, as one end drives a magneto and the other drives a propeller.

I look to do this out of a desire to have a mechanical tach, just like the venerable a65 aircraft engine.