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tachometer question

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K

kalist

Senior Member
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Does anyone know if an rvi tach., the one with the wire looped through the pickup on the back of the tach will work with a capacitive discharge ignition with a pertronix pickup in the distributor?
 
According to the Pertronix info it will if you don't do the typical double-loop thru but just run the wire thru once.
I can scan/post that section of the info if you need it.
BillM
 
Tryed everything on the electronic ignition on my Datsun engined Midget and can't get them to work. Changed my own to negative ground and tryed that and also tryed one modified by an e-bay seller that he guaranteed. Both give the same eratic operation. I'm going to swap the guts for a Steward Warner I think.

Kurt.
 
Tryed everything on the electronic ignition on my Datsun engined Midget and can't get them to work. Changed my own to negative ground and tryed that and also tryed one modified by an e-bay seller that he guaranteed. Both give the same eratic operation. I'm going to swap the guts for a Steward Warner I think.
At below about 2500 there is no reading and if the tach is calibrated to be about right at 3000 its reading 5 or 6 thou at 4000.
Kurt.
 
Tryed everything on the electronic ignition on my Datsun engined Midget and can't get them to work. Changed my own to negative ground and tryed that and also tryed one modified by an e-bay seller that he guaranteed. Both give the same eratic operation. I'm going to swap the guts for a Steward Warner I think.
At below about 2500 there is no reading and if the tach is calibrated to be about right at 3000 its reading 5 or 6 thou at 4000.
Kurt.
 
Whoops-----distracted. Not just double but triple!!!

Kurt.
 
This is the shot but I see that it is from a Crane Fireball and not Pertronix but it may help:
Bill
I can't get it to load here so PM me an email address and I'll send it.
BillM
 
Good luck. The problem isn't the number of loops or other tricks. The RVI tach was designed to work with a certain charge/discharge window that is different between points and electronic ignitions. I know of only two (2) people who have had success using an RVI with any electronic ignition. Let us know if you are successful. If not, there is no shame in replacing the RVI with an RVC. Purists have been known to fit the RVC movement behind the RVI face to keep the "original" look.
 
One of the tricks after taking ONE loop out --that is simply passing the wire through once--- is to take the back off and locate the adjustment pot(entiometer). Drill a hole in the back so that a small screw driver can be inserted to make tach adjustments "on the fly". I have a Crane unit installed and set it to read correctly at mid-range. Knowing the speed vis a vis tach readings --with a 4.22 rear end every 1000 rpm ~ 15 mph,--- I drove at 60 mph and set the tach to 4000 rpm. .. .. it may not be EXACT, but it's close enough for me...

Be sure to do this on a relatively empty, straight road. It can be a challenge to get the screw driver into the back of the tach at speed.
 
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