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#1 |
Registered User
Join Date: Jul 2002
Location: St. James, MO
Posts: 1,239
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Factory Tach Problem
As I noted on another thread, I finally got my factory tach in last night. However, it's not reading right. The idle speed seems to be real close @ about 800. But, even on the highway, where I know I'm turning about 3000, the highest the tach reads is 1500.
I should point out that, the more I've drinen it, the better it's worked, and that I've only driven it 10 or 12 miles. Am I dealing with a sticky gauge that just needs to loosen up (or be cleaned)? Does it need to be/Can it be adjusted? Or is there a more serious problem? I also should note that I'm running an HEI; the tach is hooked up to the right terminal (where my previous SunTach was). TIA.
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'69 Longstep K-10: 327/SM465/T-221/Closed Knuckle Dana44/12-bolt. |
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#2 |
Registered User
Join Date: Mar 2002
Location: Bondurant, IA but in Worcester, MA for school
Posts: 767
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Could be a bad tach...I have no clue though.
![]() HotRod
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1970 Chevy C-20 350 V-8 Turbo 350 w/ shift kit Dana 60 w/ 4.10 gears AND Powr-Loc POSI New Additions: Summit Headers 135amp alternator Proform HEI Edelbrock 1406 600cfm carb Sunpro Tach Powr-Loc POSI Edelbrock Performer RPM Intake MSD 6A Ignition Box AIM: HotRod929 Visit My Site: http://1970chevy.netfirms.com/ |
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#3 |
Registered User
![]() Join Date: Mar 2000
Location: Moncton, New Brunswick
Posts: 239
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TACH
I have discovered that mine is off quite a bit as well.
About 200 RPM higher at idle. and read 2200 at 1600.. I wonder if the adjuster at the back will bring this in. Glad to see that you got it in and working palallin. How it will be more accurate. Peter PS...make sure the tach and cluster is grounding good. The blinking wrong lights in you eariler post got me thinking of that. Last edited by HYPERMAN; 09-04-2002 at 11:42 AM. |
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#4 |
Registered User
Join Date: Jul 2002
Location: St. James, MO
Posts: 1,239
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Adjuster? Hmmm. I'll have to check (thanks, Peter!). Does anyone know which way to adjust it (I'm guessing it's a screw?).
200 rpm isn't enough to worry about to me; 1500 is a bit much ![]() I wonder if I can get to the screw without pulling the dash ![]() ![]() Thanks for the ground tip: I'm not really sure how it grounds. I do know that two of the paths on the circuit board are bad, so I have to round up one sometime: my tester showed me why neither the temp nor the amp gauge work (I may be able to wire in a temp fix for now). It really amazes me how well some of this old stuff does work after so many years.
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'69 Longstep K-10: 327/SM465/T-221/Closed Knuckle Dana44/12-bolt. |
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#5 |
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Join Date: Mar 2001
Location: Burien, WA, USA
Posts: 391
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From everything I've heard, the factory tachs tend to be pretty inaccurate, even when new. Never used one myself though, so that's second hand.
RainDog
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"Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin slitting throats." |
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#6 |
Senior Member
Join Date: Nov 2001
Location: st.louis mo.
Posts: 717
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tach ????
bad ground !!!!
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1969 cst swb 350/400 th . DANNY C . ["]FRIENDS DONT LET FRIENDS DRIVE F@RD$!! ![]() ![]() 1969 cst swb corvette hugger orange with 400 hp sbc I started out with nothing and i held on to it ![]() ![]() ![]() ![]() |
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#7 | |
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Join Date: Jul 2002
Location: St. James, MO
Posts: 1,239
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Re: tach ????
Quote:
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'69 Longstep K-10: 327/SM465/T-221/Closed Knuckle Dana44/12-bolt. |
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#8 |
Registered User
Join Date: Jun 2001
Location: Kalamazoo MI USA
Posts: 161
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Is it a used tack? If so make sure someone didn't slip you one out of a C-30-50 Diesel motor. In not sure how one out of a Diesel would read but I put one in out of a 6cyl truck and the tack reads to high. Way to high. Diesel might be way to low???
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1967 Chevy 1/2 SWB (under construction) 1968 GMC (propane-under construction) 1969 GMC Flatbed (propane) 1970 3/4 LWB (propane) 1970 Stepside 402 (gasoline) 1971 GMC Burb |
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#9 |
Registered User
Join Date: Aug 2002
Location: Muskogee, Oklahoma
Posts: 2,914
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I may be wrong, but I think there is also a 6 cylinder tach, and maybe that is what you have? Just a guess....
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#10 |
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Location: New Palestine, IN
Posts: 470
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Yes you can adjust the tach without taking it out. Reach up behind the tach and try to find a sticker. Once removed there will be a hole to put a screwdriver through. A short (maybe about 3") regular sized phillips works well.
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#11 |
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Join Date: Jul 2002
Location: St. James, MO
Posts: 1,239
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Good to hear it's possible. According to the housing, it's a V-8, which I assume also precludes the possibility that it's a diesel. Of course, the tach itself may have been changed . . . .
I will try the adjustment ASAP.
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'69 Longstep K-10: 327/SM465/T-221/Closed Knuckle Dana44/12-bolt. |
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#12 |
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Join Date: Jul 2001
Location: nw IL
Posts: 211
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I dont think the tach could be out of a diesel. Im no D. mechanic, but I DONT think they have a distributor. I think those tachs were mechanically driven?
Oh, I think the tach grounds thru the srews when mounting it in the dash? ANY WIZARDS on this? |
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#13 |
Join Date: Dec 1999
Location: Eastern - Manitoba Canada, Winnipeg
Posts: 4,369
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They can be sticky also. I have taken a few apart and cleaned them up and they have worked well.
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