Tach Problems - Recalibrate? - Team Camaro Tech
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post #1 of 10 (permalink) Old Jun 3rd, 04, 07:57 AM Thread Starter
 
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I have a '70 Z28 with the factory tach that reads about 30% low (compared to a known good hand held tach). It has an MSD HEI distributor and the fusible-link resistor wire has been removed. Does any one know of a reliable place that can recalibrate it? I'm in the south-east part of Wisconsin and would like to find some body in the area if possible. If not I guess I'll have to ship it.
Thanks.
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post #2 of 10 (permalink) Old Jun 3rd, 04, 02:18 PM
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Mark
 
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Gary "The Tachman" can recalibrate it. Not cheap though. Mine was reading low and he got it right. He has a web site. www.tachman.com (I think)

-Mark.
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post #3 of 10 (permalink) Old Jan 13th, 08, 08:56 PM
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Re: Tach Problems - Recalibrate?

i am not cheap! just do it right, is this not worth it! the tachman is the best, dare to send it so someone else! good luck all!
gee, the packers won!!! love number 4, bret farve! go pack, cowboys lost good, jerry jones can go to &&&& after dumping, tom landre in 1989
well, what else is new! got to www.tachman.com and click on my ebay auctions. you want the best you got him! the TACHMAN!
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post #4 of 10 (permalink) Old Jan 14th, 08, 09:52 AM
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Re: Tach Problems - Recalibrate?

I hope the Packers go packing. Wait'll next year! Go Seahawks!

One owner 69 Camaro,(yep, bought it new
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post #5 of 10 (permalink) Old Jan 14th, 08, 10:11 AM
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Re: Tach Problems - Recalibrate?

Many of these tachs have an adjustment pot on the PCB. If you can get the tach out of the dash and still connected, you can turn the pot until the tach reading matches your handheld.

IMPORTANT: go to radio shack and buy a PLASTIC screwdriver for this.





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post #6 of 10 (permalink) Old Jan 18th, 08, 04:32 PM
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Re: Tach Problems - Recalibrate?

Quote:
Originally Posted by JimM View Post
Many of these tachs have an adjustment pot on the PCB. If you can get the tach out of the dash and still connected, you can turn the pot until the tach reading matches your handheld.

IMPORTANT: go to radio shack and buy a PLASTIC screwdriver for this.
the pcb's do not have an adjustment pot on the circuit boards. when calibrating a tach, the meter must be balanced first, then the pcb must be calibrated. The 1967 camaro tach did have an adjustment pot. from 1968 up they did not for the pcb. not even the 1977-81 tachs that had the bi-coil meter had an adjustment pot. be careful when messing with meters and the pcbs, they are expensive to replace and hard to find. i have tons of camaro instrument parts after 29 years restoring camaro instruments. if i can help further,my email address is [email protected] thans, great forum!
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post #7 of 10 (permalink) Old Jan 18th, 08, 04:56 PM
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Re: Tach Problems - Recalibrate?

So if there is no pot, how does it get calibrated? Is it a matter of reprogramming an onboard chip?
alan
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post #8 of 10 (permalink) Old Jan 18th, 08, 05:03 PM
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Re: Tach Problems - Recalibrate?

Alan, about all you can do is pull it out and look. I know my repro tictoc has a pot, though I never needed to turn it. Steve (farm boy) put a post up a while back when he adjusted his, but I think his car is a 67.

Tachman sounds like he knows what he is doing, but with just 2 posts, both here in this thread, we don't know him yet.

For sure, don't go near that thing with a metal screwdriver. Electronics won't work if you let the smoke out.





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post #9 of 10 (permalink) Old Jan 19th, 08, 07:08 AM
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Re: Tach Problems - Recalibrate?

Quote:
Originally Posted by JimM View Post
Alan, about all you can do is pull it out and look. I know my repro tictoc has a pot, though I never needed to turn it. Steve (farm boy) put a post up a while back when he adjusted his, but I think his car is a 67.

Tachman sounds like he knows what he is doing, but with just 2 posts, both here in this thread, we don't know him yet.

For sure, don't go near that thing with a metal screwdriver. Electronics won't work if you let the smoke out.
correct, all the repops have a pot to adjust. the repro pcb is used on camaro, chevelle, etc. i have a ton of them in here (can't repair). what happens is the zener diode goes on them and it takes out the intergrated circuit (IC). since taiwan or mexico used generic parts, there are no part numbers on the chip to find a replacement. so the solution is to buy another repop! has any one seen classic industries 1970 ls-6, l-78 chevelle repro tach. the yellow line is wrong. yellow shoud go from 5700-6500 and red 6500-7000. same as the L-78 1970 camaro. heres the story about the big block square port heads and the history
1. 1969 back, hipo's used a 6000-7000 redline and yellow from 5700-6000. why? the valves on the heads had 1 spring a 1 dampner.
2. 1970 and some 71's had the yellow from 5700-6500 and the redline from 6500-7000. why? valves had "2" springs and a dampner, raising the reline to 6500 rpm. viva: less valve dropping when busting the torque on the rat motor.
this, of course, applies to the 7000 rpm tachometers. different story on the late 69 and 1970-72 z-28 tachometers. hope this helps.
many say there were no 1971 ls-6 cars made, but not true. they were 454-425 hp, but about 60 were made. any body have the facts on this one?
tks
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post #10 of 10 (permalink) Old Jan 22nd, 08, 06:35 PM
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Thumbs up Re: Tach Problems - Recalibrate?

correct, all the repops have a pot to adjust. the repro pcb is used on camaro, chevelle, etc. i have a ton of them in here (can't repair). what happens is the zener diode goes on them and it takes out the intergrated circuit (IC). since taiwan or mexico used generic parts, there are no part numbers on the chip to find a replacement. so the solution is to buy another repop! has any one seen classic industries 1970 ls-6, l-78 chevelle repro tach. the yellow line is wrong. yellow shoud go from 5700-6500 and red 6500-7000. same as the L-78 1970 camaro. heres the story about the big block square port heads and the history
1. 1969 back, hipo's used a 6000-7000 redline and yellow from 5700-6000. why? the valves on the heads had 1 spring a 1 dampner.
2. 1970 and some 71's had the yellow from 5700-6500 and the redline from 6500-7000. why? valves had "2" springs and a dampner, raising the reline to 6500 rpm. viva: less valve dropping when busting the torque on the rat motor.
this, of course, applies to the 7000 rpm tachometers. different story on the late 69 and 1970-72 z-28 tachometers. hope this helps.
many say there were no 1971 ls-6 cars made, but not true. they were 454-425 hp, but about 60 were made. any body have the facts on this one?
tks
tachman
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