Console Mounted Tach Reading High

[68VAHCODE]

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

 

[RustyRatRod]

It probably needs a tachometer filter. It's a common problem with hot ignitions.

 

[68VAHCODE]

I see several posts on the subject...should have searched first......let me see if I can figure this out

 

[68VAHCODE]

It probably needs a tachometer filter. It's a common problem with hot ignitions.

That something you can buy at Summit I suppose?

 

[RustyRatRod]

That something you can buy at Summit I suppose?

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.

 

[yellow rose]

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.

 

[dart4forte]

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?

 

[68VAHCODE]

Yes.....it goes to what looks like some kind of sending unit just in front of the bell housing...see attached.

 

[mopardude62]

That's the oil pressure sending wire. The tach wire should go to the coil.

 

[krazykuda]

@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...

 

[dart4forte]

Bump