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Bouncing Tach

PostPosted: Sun Jul 05, 2020 10:06 pm
by Pete M
Could someone confirm my thinking? My '71 Elan s4 has electronic ignition and an RVI tach which bounces around a lot and may not provide accurate readings. My information, so far is that if I buy an RVC tach from another 4 cylinder MGB (for example) and change the wiring, it will work in my car. If my info is correct, you wire the RVC to the negative side of the coil but do you also need a 12 volt source?

Re: Bouncing Tach

PostPosted: Sun Jul 05, 2020 10:08 pm
by pharriso
Do a search on spiyder tacho conversion, highly recommended. No other wiring mod(s) required.

Re: Bouncing Tach

PostPosted: Sun Jul 05, 2020 10:26 pm
by Pete M
Thanks, Phil. This looks a little beyond my skill level. I wonder if my original plan would work better for me.

Re: Bouncing Tach

PostPosted: Sun Jul 05, 2020 10:59 pm
by pharriso
Pete M wrote:Thanks, Phil. This looks a little beyond my skill level. I wonder if my original plan would work better for me.

You can mail your Tacho to them & they will do the conversion & calibration for you.

Re: Bouncing Tach

PostPosted: Sun Jul 05, 2020 11:42 pm
by Craven
Your RV1 will have the necessary + 12volts supply already, and yes you connect the pulse input on a RVC to the negative side of the coil.
No guarantee it will work with electronic ignition though.

Re: Bouncing Tach

PostPosted: Mon Jul 06, 2020 11:59 pm
by Pete M
Phil,

I looked again and found Youtube videos on how to do this. It actually looks well within my skill level. I've ordered one and wanted to thank you for the good advice.