Tach dash question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

f.monroe · 05-14-2005, 12:07 AM

I have a tach dash from a 1980 one ton 454 truck . I was going to use this in my 77 because I like the look of these gauges better but have decided to use a 77 gauge panel instead . I have a question . There is a resistor ??? ( looks like a conderser for a points type distributor )or something that plugged into the distributor , mounted to the firewall , and then hooked to the tach wire . What is this part used for . I have seen tach dashes where the wire runs from the tach straight to the distributor . Just curious about this one part . Frank

Russell · 05-14-2005, 01:20 AM

I'm not sure exactly what it does, but there is no harm in leaving it there. My tach does not have one hooked up to it though...

jermasaurus · 05-14-2005, 01:26 AM

I think it is a capacitor that keeps your tach from jumping around when voltage is used. For example, I put in a full set of factory gauges in my 87 monte carlo and ran a wire strait from the negative terminal of the coil up to the connector. When I would use my turn signal or hit the brakes at idle, the tach would bounce up about 100 RPM or so when the turn signal blinked.

NeCrOmAnCeR · 05-15-2005, 10:51 AM

jermasaurus is correct, it is a tach filter. Used to eliminate any "high frequency" noise from causing erratic tach operation.

05-14-2005, 12:07 AM	#1
f.monroe Senior Member Join Date: May 2004 Location: Caldwell,Tx. Posts: 3,648	Tach dash question I have a tach dash from a 1980 one ton 454 truck . I was going to use this in my 77 because I like the look of these gauges better but have decided to use a 77 gauge panel instead . I have a question . There is a resistor ??? ( looks like a conderser for a points type distributor )or something that plugged into the distributor , mounted to the firewall , and then hooked to the tach wire . What is this part used for . I have seen tach dashes where the wire runs from the tach straight to the distributor . Just curious about this one part . Frank Last edited by f.monroe; 05-14-2005 at 12:08 AM.

05-14-2005, 01:20 AM	#2
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I'm not sure exactly what it does, but there is no harm in leaving it there. My tach does not have one hooked up to it though... __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

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05-14-2005, 01:26 AM	#3
jermasaurus Registered User Join Date: Dec 2004 Location: New Lenox, IL Posts: 442	I think it is a capacitor that keeps your tach from jumping around when voltage is used. For example, I put in a full set of factory gauges in my 87 monte carlo and ran a wire strait from the negative terminal of the coil up to the connector. When I would use my turn signal or hit the brakes at idle, the tach would bounce up about 100 RPM or so when the turn signal blinked.

05-15-2005, 10:51 AM	#4
NeCrOmAnCeR Registered User Join Date: Feb 2004 Location: Hodgenville, Ky Posts: 735	jermasaurus is correct, it is a tach filter. Used to eliminate any "high frequency" noise from causing erratic tach operation.



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