Mechanical Tach

[Greg Kingman]

Hey fellow A-4 owners-
Does any one else out there have a mechanical take off for their Tachometer, and if so, is it possible it is set for gear reduction?
I have never been able to get my A-4 to register over 1200 RPMs on the tach and am looking for an explanation.
Cheers,
Greg

[jhwelch]

I had to replace my previous tach when it started reading too high, then way too
high, and then the needle hit the far stop. And my newer one was reading
50% or 100% too high yesterday, maybe some moisture or corrosion has
gotten into it.

Check the little switch that lets you pick 4, 6, or 8 cylinders and move
it around a bit. Perhaps there is a bad electrical contact and moving it
will clear it up.

-jonathan

[67c&ccorv]

Jonathan, I think Greg is saying he has a mechanical tach and is wondering why it doesn't register over 1200rpm - is that correct Greg?

[Greg Kingman]

Yes , that is correct. I have a mechanical Tach (that is with a cable running to a takeoff at the distributor Base). Is it possible that this has somehow been adjusted for 2:1 power reduction and thus only reads half of what the motor is actually turning?
Thanx,
Greg

[MikeB.330]

No, The tach is reading crankshaft speed not prop shaft speed. The crank doesn't know or care what it's attached to so there's no reason for the tach to read 1/2 speed.


Mike

[67c&ccorv]

Greg - what year is your motor?