LT1 to 1968 guages
Thread Starter
6th Gear
Joined: May 2006
Posts: 6
Likes: 0
LT1 to 1968 guages
I am planning on putting one of the LT1 & 8L90-e automatic
transmission GM Connect & Cruise packages into my 1968 (car bought new, but has a non-number-matching 427 engine) so I do not feel bad about this swap.
I would like to retain the tachometer, speedometer, and the other guages except the amp guage (swap in a voltmeter).
Does anyone make electronic and/or mechanical adapters for these changes?
Hoping someone has experience of putting an LT1 in a C3 car.
transmission GM Connect & Cruise packages into my 1968 (car bought new, but has a non-number-matching 427 engine) so I do not feel bad about this swap.
I would like to retain the tachometer, speedometer, and the other guages except the amp guage (swap in a voltmeter).
Does anyone make electronic and/or mechanical adapters for these changes?
Hoping someone has experience of putting an LT1 in a C3 car.
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
You picked an uphill battle there.
There are mechanical speedo adapter for the 4L60/80 but don't know of any for the 8L90. I've heard of people having success with the Abbott cable x box.
With the tach, you can swap the electric 77 vette tach internals. I used an Isspro tach with the same sweep as the 68, swapped those internals.
The 68 temp sender is 1/2" or 3/8" NPT. Way too big for the small metric temp sensor in your heads. The LS blocks had big threaded brass block plugs on the drivers side that are perfect for tapping for the 68 vette sender. You'll have to check the LT1 block.
Mechanical 1/8" NPT oil port can be used in the huge metric LS1 block oil pressure sender location. Speedway motors sells the adapter for the LS blocks, maybe the same for the LT.
With a little experimentation you could retain the amp gauge, I managed.
There are mechanical speedo adapter for the 4L60/80 but don't know of any for the 8L90. I've heard of people having success with the Abbott cable x box.
With the tach, you can swap the electric 77 vette tach internals. I used an Isspro tach with the same sweep as the 68, swapped those internals.
The 68 temp sender is 1/2" or 3/8" NPT. Way too big for the small metric temp sensor in your heads. The LS blocks had big threaded brass block plugs on the drivers side that are perfect for tapping for the 68 vette sender. You'll have to check the LT1 block.
Mechanical 1/8" NPT oil port can be used in the huge metric LS1 block oil pressure sender location. Speedway motors sells the adapter for the LS blocks, maybe the same for the LT.
With a little experimentation you could retain the amp gauge, I managed.
Last edited by Garys 68; Sep 19, 2017 at 05:24 PM.
Melting Slicks
Joined: Oct 2007
Posts: 2,702
Likes: 192
From: Northwestern Connecticut
St. Jude Donor '10 thru '26
TCI and Dakota digital also make cable drive boxes to run a stock mechanical speedometer. Autometer makes an LS adapter kit for the temp senders etc. I'm not sure what to do about the tachometer though since stock is cable driven also. There is a company that converts mechanical speedometers to electronic, maybe they can do a tach conversion as well. I'll try and find there info.
Edit, found it, no association. http://redlinegaugeworks.com
Edit, found it, no association. http://redlinegaugeworks.com
Last edited by 68sixspeed; Sep 20, 2017 at 10:57 PM.
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
Take a look at the Dakota Digital HDX gauges. They really add a lot of nice features and a modern touch to the car. The interfacing is easy too. If you like them then call them and see if they're working on a set for your car. They already have the VHX available which is similar but with simpler displays and maybe you'd like it better anyways.
One nice thing about these gauges is that they have all the lights like the high beam, signals, e-brake warning etc built-in to the gauge faces like a modern car cluster. If you put individual aftermarket gauges into the dash they don't have these lights in them.
One nice thing about these gauges is that they have all the lights like the high beam, signals, e-brake warning etc built-in to the gauge faces like a modern car cluster. If you put individual aftermarket gauges into the dash they don't have these lights in them.
Thread Starter
6th Gear
Joined: May 2006
Posts: 6
Likes: 0
Dakota Digital Displays
Take a look at the Dakota Digital HDX gauges. They really add a lot of nice features and a modern touch to the car. The interfacing is easy too. If you like them then call them and see if they're working on a set for your car. They already have the VHX available which is similar but with simpler displays and maybe you'd like it better anyways.
One nice thing about these gauges is that they have all the lights like the high beam, signals, e-brake warning etc built-in to the gauge faces like a modern car cluster. If you put individual aftermarket gauges into the dash they don't have these lights in them.
One nice thing about these gauges is that they have all the lights like the high beam, signals, e-brake warning etc built-in to the gauge faces like a modern car cluster. If you put individual aftermarket gauges into the dash they don't have these lights in them.
Thanks for pointing me in their direction.
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
I did a "newer" engine swap and just had the gauges converted by Corvette Instrument Service in Florida. No need for any "adapters."
He did the tach- speedo - volt- and even a oil temp gauge to replace the clock- important if you are running a Dry sump.
Even doing a custom dash- would have been easier to go w/ new gauges - but the originals just look too good.
Dakota-
Originals redone-
