Original Chevy Speedo with V8 conversion?

Hey all.

I have a techy question regarding speedometers. I have a 1953 chevy with the original dash controls. The car has undergone a v8 swap with new diff and gearbox. I wanted to see if there is a way of having an accurate fully functioning speedo with the new driveline without loosing the look of the original speedometer. Maybe by replacing the guts of the speedo behind the original face? I'm not sure. Has anyone got advice on this?

Cheers

J

 

You should be able to simply hook the speedometer up to the transmission- but to get the speedo accurate you'll need to change the gears on the transmission tailshaft. maybe.

What did you swap in?

 

Currently the car has an Australian 4 speed and 2.78 radio diff. BUT it will be getting a turbo 700 gearbox in the near future for highway cruising.

 

the speedo really doesn't care what trans or engine is in there...it just reads the revolutions from the speedo gear...also there are many speedo gear boxes that will correct any deviations coming out of the trans or rear end ratio...

your question reminds me of a question I sent in to a rod magazine in the 50s when I was a kid..."Wanted to know what I had to do to install a hemi Chrysler in a '50 Chev and I mentioned that I knew I would have to change my vacuum wiper to electric as the Chrysler cars all had elect wipers...."

 

All American speedometers that are driven by the transmission are 1:1 or 1000 cable revolutions per mile. So calibration is done on the transmission end with the speedometer driven gear by changing the number of teeth. Or by using a speedometer gear ratio adapter. When you get it running I can help you get it dialed in. Or see your local speedo shop.

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Thanks guys. I've never done anything with speedos before but from what you've all said it appears reasonably straight forward. Sweet deal.