Skruball73

Right now I don't know what model of HEI distributor I have, it was already on the 350 eng. but it is not the correct one to allow my mechcanical tach to work. Can an HEI distrib be fitted with something for a mech tach drive or will I have to hunt for an HEI with tach drive all in one unit?




[Modified by Skruball73, 11:33 AM 1/16/2002]

Monkeywrench

Check this thread
http://forums.corvetteforum.com/zerothread?id=216057

Smokehouse69

You have a couple of choices, first buy an electric tach from a 75 or 76, and put it in your dash. This might be the cheapest alternative since you already have an HEI. I bought on off E-Bay for $75.00. The next thing would be to get a mechanical tach with tach drive and go back to point ignition. I know that Lars (distributor expert par excellance) loves point ignition, I'm more of an electronic ignition sort of guy. If you buy mechanical tach. you have a couple of options you can replace the points with a Mallory Uni-lite electronic ignition or Pertronix Electronic ignition, or send the distributor to a specialist and have it converted to HEI.
http://www.davessmallbodyheis.com/ does the conversion
General Motors Corvette FI and/or tach drive
This conversion is remote module mount only, and does not permanently alter the distributor.
Full HEI conversion — $175.00

Or you can buy an HEI tach drive distributor for about $450-550, from Summit or Jegs (I haven't looked for the exact price, but it is in that range.)

BeaterShark

Smokehouse69, what are the connections to the tach? I just aquired a '75 tach and have not really spent the time to figure out the connections.

Smokehouse69

Chris,
I wish you hadn't asked that, it has been a while. Seems like there are 3 terminals on the back of the tach, one is 12V, one ground and one tach signal from the coil or distributor. Make sure you use a tach filter to cut down on the jumping around of the tach.
The problem is that I can't remember which terminal is which, Zwede provided me with the pinout several months ago, and I have sense slept!
Sorry.

V8yunkie

There is a HEI-Distributor with mechanical tach (e.g. available from PAW9 - but it is over 400$. Was lucky on my car: The preowner spent the bucks for me.

Skruball73

Thanx for the info...one other question...could anybody take a fair stab at guestimating how likely it might be to find a used HEI dist. with mech tach drive from say like a used vette parts dealer or something instead of having to purchase one outright from mail order and major dealers?

Flareside

Unfortunately, your chance is very close to 0%. GM never made the distributor you're talking about. The only one available is custom made by an aftermarket company for someone that really wants it and is willing to pay for it.

stevebei

These are the tach electrical connections. Looking at the back of the tach there are 3 spade terminals. Two on top and one below. Top left is "pos+", top right is "neg-" and the bottom connector goes to the "dist" terminal on the HEI distributor cap.

BeaterShark

Thanks stevebei, that was just what I was looking for.