Console Mounted Tach Reading High

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68VAHCODE

68VAHCODE

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All....just installed my console mounted tach on my '68 GTS 383 4Sp which originally had a standard points ignition.

I had already replaced that ignition with a PerTronix Ignitor solid state ignition 1381A....now tach appears to be reading high.....appears to be double what it should be.....anybody have any thoughts.
Thanks
Greg
 
It probably needs a tachometer filter. It's a common problem with hot ignitions.
 
I see several posts on the subject...should have searched first......let me see if I can figure this out
 
68VAHCODE said:
That something you can buy at Summit I suppose?
Click to expand...

It is, but I prefer the mid 70s Corvette version. It's a very simple condenser design with one wire in and one wire out. I found mine on Ebay.
 
If it wasn't double what it should be I'd say it's the tach. Most of them are off. I had several Autometer tachs that were off by as much as 500 RPM at 8500.

The cheap Autogage I have now is off 250 at 1000, a hundred at 2500 and is dead nuts at 3200.

I used to send them out to have them checked and verified but the ignition I have now can check the tach.
 
I had to have my tach retired to accept an electronic ignition. Wiring on the old console tachs were pretty complicated. Guy in Seattle did mine. Do you have a gray wire coming off the firewall?
 
Yes.....it goes to what looks like some kind of sending unit just in front of the bell housing...see attached.

SENDING UNIT.JPG
 
That's the oil pressure sending wire. The tach wire should go to the coil.
 
@Eddie348 knows a little about this issue< I can't remember what he said the fix was, but maybe he can stop in here and help...
 
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