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Old 02-20-2009, 11:43 AM   #1
maxreps
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Tach problem

I have an autogage 5" tach by Autometer and MSD 6A box as well as the msd tach adapter box. When the truck is idling the tach reads 0 but it is responsive to revving and driving. It just appears to be off by whatever the idle speed is... I've gone through the wiring and verified hookup for both boxes and the tach, even ran the tach signal wire directly to the 6A box bypassing the adapter but no change. It's reading but reading about 800-900rpm low. Ideas or should I just contact MSD first, then Autometer?
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Old 02-20-2009, 12:27 PM   #2
James McClure
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Re: Tach problem

I'm going to ask a really dumb question. Does the tach have a 4, 6, 8 switch on it someplace? My Sun tach does and it drove me nuts for a while. jim
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Old 02-20-2009, 01:45 PM   #3
maxreps
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Re: Tach problem

No it has the wire loops that you have to cut if you have a 6cyl or 4cyl but if it's an 8cyl you leave them alone...
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Old 02-20-2009, 02:22 PM   #4
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Re: Tach problem

I run an Autogage 5" monster tach with a 6A box and no adapter. Hooked right up the tach terminal on the box.

I believe the MSD manual said I would need the tach adapter for anything Autogage, but I used a small Autogage 3 and 3/8' tach and the 5" tach I currently have now, and they both work without the adapter with no issues.

See if you can borrow a spare tach to try with it.
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Old 02-20-2009, 09:09 PM   #5
maxreps
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Re: Tach problem

yeah I think I'll try to find a tach to try temporarily... after reading some of the info I have on my MSD a while back some of the autometer stuff needed it and others didn't. So that is why I tried with/without the adapter. I'm gonna try again without to be sure.. then look for one to try temp.

thanks
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Old 02-20-2009, 11:44 PM   #6
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Re: Tach problem

if you got a dwell meter hook it up and compare the 2 that will definately tell you
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Old 02-21-2009, 09:10 AM   #7
maxreps
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Re: Tach problem

That I do not have... got a digital multimeter for voltage/current/resistance of both AC and DC circuits, even reads temperature but I have no dwell meter.
If I can locate one how should it be hooked up? in place of the tach or in line with it, etc...

thanks!
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Old 02-22-2009, 04:30 PM   #8
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Re: Tach problem

it's been a while but it should go in line like a timing light i'm going to be useing my dads this week i'll let you know
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