Air Guide Speedo Calibration Question. MPH VS KM

Hello,

Recently, I acquired two mint NOS Air Guide Speedo's. These are the ones that were used in the 70's and early 80's. They are the tall chrome units. The chrome on my two older speedos that are currently mounted on my 80 SN are not in perfect condition. I have been keeping an eye out for some speedo housings with better chrome, and was also considering rechroming my current speedos. I just purchased two mint units with Black Faces, but they are 0-80 KM and not the 0-50 MPH (USA). They have never been used. I can swap my current internals into these two new housings, but I have another idea that I want to run by you guys.

When you look at a car speedo 80 KM is very close to 50 MPH. When you look at the Air Guides with the White Face Overlays that have the 0-50 MPH and 0-80 KM on the same face, it appears that 80 KM is very close or equal to 50 MPH.

Last winter, I restored the faces and needles on my two current Air Guide Speedos with the 0-50 MPH Black Overlays from Don (DWCAR) in Houston. The came out great and I dialed both Speedo's in with my hand held GPS. They worked great all summer. Today, I ordered some more 0-50 black overlays from Don C.

This is my question:

Am I correct to think that the 1970's and 1980's Airguide internals are the same on the MPH and KM units? Can I just place a 0-50 MPH black overlay on top of the black 0- 80 KM overlay? When I dial it in with the GPS will the speedo with the new face read correctly in MPH?

Any thoughts would be greatly appreciated.

Thanks,

Donald

Pete,

I was hoping you would see this. Thanks for the help.

Thanks again,

Donald

Tim,

Thanks.

Donald