[alfa] Tach drive on waterpump

[AlfaNeely@xxxxxxx]

In a message dated 10/27/2003 5:15:48 PM Central Standard Time, 
owner-alfa-digest@domain.elided writes:

> Date: Mon, 27 Oct 2003 12:19:36 -0700
> From: alfacybersite <acs@domain.elided>
> Subject: [alfa] Tach drive on waterpump
> 
> Should the tach drive end rotate freely when not in use? Does oil
> pressure (or?) force the internal drive pin to turn the gear by friction
> alone? (I switched out the tach gear from an older water pump and
> installed in 2000 engine). It rotated freely in the old pump also.
> 
> On customer's 1750 engine the tach cable is to firmly attached to the
> drive to remove, but can't turn the cable by hand. Checking on another
> 'loose' engine (which has sat for eons, including outdoors) its drive
> won't move - but could be frozen.
> 
> Pressing two small shafts together by friction alone doesn't seem like
> an accurate way to drive a tach.
> 
> Biba
> Irwindale, CA USA
> 
> 

       I have never paid attention to the tach drive.  I assume they turn 
only when the engine turns.  I do not have an early engine handy to check out.
       But one thought.  What year spider did you install the tach drive on?  
There is a worm gear that drives the tach drive.  Or there is on the early 
cars with a mechanical tach.  
       However, the late cars with electronic tachs and no tach drive in the 
waterpump have a smooth shaft on the front of the intermediate.  The worm gear 
I am talking about is on the part of the intermediate timing chain idler.
       I put an early intermediate timing chain idler in my 1984 spider race 
car so that I could hook up a mechanical tach at some time in the future.  
However, that requires removing the engine front cover, which in turn requires 
removing the cylinder head and the oil pan.

Ciao,
Russ Neely
Oklahoma City
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