Re: Tachometer conversion

Rex Funk (rexfunk(at)magick.net)
Tue, 7 Jul 1998 01:30:08 -0700

I had the same problem when I ran a 1725 cc engine in the S II and III. The mechanical tach has a special distributor base with gear driven drive for the tach. I didn't like the way the tach jumped around (it reminded me of the speedometer), so I installed a S V impulse tach. Big improvement. In studying the two types of distributer bases, I concluded that they could not be interchanged. The cable tach base was made for the 1600 cc engine, and is a different height to allow for the different depth of the distributor drive shaft in the 1600 cc engine. You can interchange distributors between the two engines, but not bases. I suppose anything is possible, but I have never seen a mechanical tach base conversion for a 1725 cc engine. Most people run the steadier electronic tach, and some (including me) run the electronic tach even with the 1600 cc engine and mechanical tach base "unplugged". Hmm- - - I wonder how much horsepower that tach drive gear is robbing from my engine?

The S V tach looks enough like the early I-III tach not to stand out. You can carefully remove the needle and lightly spray-paint it the same color as the needles on your other guages for a better match. The flourescent orange for the S III is halfway between flourescent orange and red as sold in most stores. A 50/50 mix is about right.

The S II mechanical tach does incorporate the turn indicator and ignition lights on the face. I have a wood dash, and used seperate lights from a S V for the turn indicators. I have a S II tach that someone tried to "marry" to a S V electric tach in order to save the indicator lights. It's not working, and it looks cobbled together, but I guess a pro, or someone more patient could do a better conversion. There are a number of modifications that need to be made, and it looks like more than a one or two beer job. There are many tech tips covering how to set up and adjust an electronic impulse tach. Check TEAE's "The Sunbeam Survivor".

Good luck.

Rex Funk ---------- > From: LOsoccer(at)aol.com
> To: alpines(at)autox.team.net
> Subject: Tachometer conversion
> Date: Monday, July 06, 1998 7:07 PM
>
> My Ser III has a mechanical tack. I am putting in a 1750 engine that
has an > electric tack. I don't want to change the appearance of the tack face
and > would perfer the electric tack. Has any one made the switch? Does a
Ser V > tack look like a Ser III? Is there an adapter for the distributer for
the > mechanical tack? Help