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Tach and Oil Pressure Guage questions

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Killerdave8813
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Tach and Oil Pressure Guage questions

Post by Killerdave8813 » Sun Oct 30, 2011 8:54 pm

Hey Guys & Gals,
Especially electrical Gurus,does anyone know how to calibrate and wire a G-body (Monte SS) factory tach to work properly with the 200 V-6 in my 78 Bu? I have a Tach dash and the wire with the filter? in it,any info would be appreciated!! Also same car has factory guages and the oil pressure guage is all kind of haywire jumping around like a vacume guage on a car with a bunch of cam in it,
my guess is the guage is junk? Any input before I rip the dash apart? As with the other question any info/help would be appreciated!! Thanks,KillerDave
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81 Malibu Ex V-6 3spd,267 V-8 305 HO cam,600 Holley,HEI,Dougs Headers,3" Pypes exhaust w/ X-pipe,168 toothflywheel,11"clutch,
Muncie M-20 big spline trans,Hurst Comp Plus shifter,3 1/2" steel driveshaft,Moser 9" 3:50,Edelbrock adj uppers,Southside lowers,
Modified Moog springs,Cop Car gearbox,antisway bars & frame braces,
urethene bushings,Goodmark hood,More coming soon!

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Doober
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Re: Tach and Oil Pressure Guage questions

Post by Doober » Tue Nov 01, 2011 3:00 pm

There is a capacitor and resistor in the tach that calibrate the signal from the coil. You won't need the filter either, that was just to filter out RFI so you don't get noise from the radio (whine, etc.).

The "easy" way out is this, however expensive:
http://www.dakotadigital.com/index.cfm/ ... prd127.htm" onclick="window.open(this.href);return false;

I know the resistor calibrated for the v8 is around 210-215k ohms. I'm not sure what it is for the v6, but I'm pretty sure the mentioned capacitor would also need to be changed, otherwise as RPM climbed it would read wrong. Eventually I quit messing with the factory one and hooked up a SunPro tach for now.

Far as the oil pressure gauge, it's just a simple sensor that is wired to the gauge, similar to a temperature sensor. So long as you have the proper year/engine application for the cluster, you could get the resistance range for the sensor, and if the replacement sensor doesn't fit your engine block, just use the resistance range as a reference.
This one is for a 60psi gauge... it's what I have in mine with an '87ish Monte cluster, and it actually came off an '88 350 from a pickup. It's $8.60 from RockAuto.com
http://www.rockauto.com/catalog/moreinfo.php?pk=939037" onclick="window.open(this.href);return false;
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Killerdave8813
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Re: Tach and Oil Pressure Guage questions

Post by Killerdave8813 » Wed Nov 02, 2011 9:16 pm

Hey Doober,
How ya been? I thought my question might bring you around!! That comlicated for the tach huh? Well I'm going to end up with the Tuned Port 267 I've been threatening to build in this car eventually any way so it won't be a big deal then,I thought if it were something easy,well you know! As far as the pressure guage goes it had a bad sender
(leaking) when I bought the car and I replaced it with a genuine GM sender and it worked fine for a while,just started going haywire in the last couple of weeks,I guess I should do the normal checks befor I jump to conclusions but I just feel the guage is bad,of course it could be a bad ground too!!,Oh well I'll get to the bottom of it on day here soon!! Good to hear from you Doober!! I still havn't pulled that green interior yet if you're interested,It won't be too long before I do!! Later,KillerDave
Image
81 Malibu Ex V-6 3spd,267 V-8 305 HO cam,600 Holley,HEI,Dougs Headers,3" Pypes exhaust w/ X-pipe,168 toothflywheel,11"clutch,
Muncie M-20 big spline trans,Hurst Comp Plus shifter,3 1/2" steel driveshaft,Moser 9" 3:50,Edelbrock adj uppers,Southside lowers,
Modified Moog springs,Cop Car gearbox,antisway bars & frame braces,
urethene bushings,Goodmark hood,More coming soon!

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Doober
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Re: Tach and Oil Pressure Guage questions

Post by Doober » Thu Nov 03, 2011 12:25 am

Doin' pretty good :) The printed board could be corroded (traces are copper and it's just two layers of plastic sandwiched together), that would be my first guess, either that or a poor connection to the harness at the dash.
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MR.com Facebook page
'92 Sierra - EBL/TBI-fed Vortec 383/700R4/3.08
'87 Fiero GT - 2.8/5-speed
'78 Malibu - Vortec 350/4-speed (for now)

User avatar
Killerdave8813
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Re: Tach and Oil Pressure Guage questions

Post by Killerdave8813 » Fri Nov 04, 2011 10:12 pm

Thanks Man,
I'll look at all that stuff but I have a Monte SS dash to stick in there for the V-8,I might as well have a Tach that don't work for now as opposed to a clock that'll never work!! I've just got way to many projects
these days!! Later On!! KillerDave
Image
81 Malibu Ex V-6 3spd,267 V-8 305 HO cam,600 Holley,HEI,Dougs Headers,3" Pypes exhaust w/ X-pipe,168 toothflywheel,11"clutch,
Muncie M-20 big spline trans,Hurst Comp Plus shifter,3 1/2" steel driveshaft,Moser 9" 3:50,Edelbrock adj uppers,Southside lowers,
Modified Moog springs,Cop Car gearbox,antisway bars & frame braces,
urethene bushings,Goodmark hood,More coming soon!

User avatar
Killerdave8813
Dragway Regular
Posts: 869
Joined: Wed Jan 16, 2008 5:16 am
Location: Cincinnati,Ohio

Re: Tach and Oil Pressure Guage questions

Post by Killerdave8813 » Thu Nov 10, 2011 12:56 am

Hey Doober,
Here's a good one for the I feel like a Dumb As$,should look before you leap,sometimes thinking too much is a bad thing file,the oil pressure guage issue,loose plug! The other morning I fired it up and the guage was pegged wide open! I said to myself,self what do you want to bet if you look the plug will be disconnected? Well shure enough,just kinda dangleing there!! Plugged it back on the sender and it works like brandy new!! I'm guessing that when it was going all haywire is because the plug was loose and wiggeling around on the sender!! Well an easy fix anyway!! Catch Ya Later! KillerDave
Image
81 Malibu Ex V-6 3spd,267 V-8 305 HO cam,600 Holley,HEI,Dougs Headers,3" Pypes exhaust w/ X-pipe,168 toothflywheel,11"clutch,
Muncie M-20 big spline trans,Hurst Comp Plus shifter,3 1/2" steel driveshaft,Moser 9" 3:50,Edelbrock adj uppers,Southside lowers,
Modified Moog springs,Cop Car gearbox,antisway bars & frame braces,
urethene bushings,Goodmark hood,More coming soon!

User avatar
Doober
Moderator
Posts: 14704
Joined: Mon Jun 02, 2003 11:15 pm
Location: Catalina, AZ

Re: Tach and Oil Pressure Guage questions

Post by Doober » Thu Nov 10, 2011 10:57 am

Heh heh, I've definitely had those moments :lol: Just last night actually... I'd downloaded a previous episode of American Horror Story to watch, and was in the process of moving the laptop near the tv/receiver/etc. After seitching to the proper inputs I realized I hadn't plugged the HDMI cable into the laptop :roll:
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MR.com Facebook page
'92 Sierra - EBL/TBI-fed Vortec 383/700R4/3.08
'87 Fiero GT - 2.8/5-speed
'78 Malibu - Vortec 350/4-speed (for now)

User avatar
Killerdave8813
Dragway Regular
Posts: 869
Joined: Wed Jan 16, 2008 5:16 am
Location: Cincinnati,Ohio

Re: Tach and Oil Pressure Guage questions

Post by Killerdave8813 » Sun Nov 13, 2011 1:02 am

Hey Doober,
I meant to tell you about an interesting bit of Malibu trivia,I changed the heater core in the 78 the other day,Ac car,when I went to put it back together I decided to do it right and seal the box top to the bottom with fresh strip caulk since I happen to have some,well anyway it takes exactly 4 full strips of 3M strip caulk to seal the box,not 3-1/2 or 4-1/4 but exactly 4 lengths and it's configured in such a way that you use the complete strips,no partials at
all!! Coincedince??? I don't know but it shure felt like it was designed that way when I started laying them in the grooves!! Pretty wierd Huh? Catch Ya Later!!
Image
81 Malibu Ex V-6 3spd,267 V-8 305 HO cam,600 Holley,HEI,Dougs Headers,3" Pypes exhaust w/ X-pipe,168 toothflywheel,11"clutch,
Muncie M-20 big spline trans,Hurst Comp Plus shifter,3 1/2" steel driveshaft,Moser 9" 3:50,Edelbrock adj uppers,Southside lowers,
Modified Moog springs,Cop Car gearbox,antisway bars & frame braces,
urethene bushings,Goodmark hood,More coming soon!

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