What size aftermarket tach fits in the dash of a 1968 Olds Cutlass Supreme? From researching I think it would be the 3 3/8", but I am not sure. Any help would be appreciated. Thank you!

 

Surely, someone knows or has done this.

 

This was mine. It was a Mercruiser tach but I sold it so I can't tell you for sure what size it was. I think it was 3 1/2". A stock gauge is about 4 1/4" so anything smaller than that will fit

 

I like that. It looks really nice. Did it fit in without much modification?

 

I used a 3 1/2" hole saw to cut a hole in a clock delete plate and used that to mount it but with a little tweaking you could gut any factory gauge to act as a mounting pod

I found another pic I have of it. It came out nice. If I didn't find a nice factory tach/gauge set I never would have gotten rid of it

 

Or how about this one, made to match the other gauges and fit right in without any modifications, replaces the clock or blank plate. OPGI at around $145

 

I have read on these forums that those repro pieces are kinda junky and made of plastic. I've even seen one that wasn't completely sealed. That's why I want a nicer unit, such as the American Muscle unit from Autometer.

 

I bought one of those pieces of junk. It doesn't work with an MSD ignition. I bought mine when I first started my restoration. By the time I was able to start the engine, it was out of warranty. I called the dealer and they put me in touch with the guy that makes it. When I told him my setup, he criticized me for using an MSD box. Says it works with points or an HEI. I have an HEI triggered by a 6AL. He gives me move grief about the MSD. He finally told me that the movement inside was from some 80’s GM car. No help other than that.

I called the MSD tech line and they said that the 80’s something tach movement should work when plugged directly into the 6AL’s tach output. It didn’t. They suggested that I try a MSD 8920 Tach Adapter. Well another $60 and that made it work, well sort of. By the time I finished the restoration and put the pedal to the floor, I discovered when my MSD rev limiter hit 6400 rpm, the tach was reading 5000. Not another penny on this piece of ….

Before the restoration I had a cheap Auto Gage tach that worked perfectly with my setup. I just wanted something that looked original.

Buyer beware…

 

In my 72 I used a sunpro suntach in a gutted column shift speedo housing fits in there nicely and I think it looks OK

IDK if the 68 guage holes are the same diameter as the 72

 

Is the 68 the same size as 72?
If so, 3 3/8" fit perfectly.
DSCN0143.jpg

 

Gary those look real nice, please provide brand and availability. Thx.

 

Dolphin gauges, search google or ebay. No mods, bolted right in.

 

Hello Mr Gary! I know this thread is old but I'm at the gauge stage and as far as i know yours is the only post that says "no modification bolt right up" that's what i need I'm definitely a newbie. My real question is how does your Dolphin gauges look at night? Do you have any pictures of them illuminated? Thanks