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#1 |
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![]() Join Date: Jul 2008
Location: auburn ma
Posts: 216
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Tach dash question, need help.
I have a 1971 k5 blazer... Truck did not have a tach dash in it. I just got a complete dash that looks to be in great shape with no burn marks on circuit board. My question is.
Is there a way to tell if the truck the tach dash came from is a 8 or 6 cyl? Is there a way to make it work if it was from a 6cly? Is it as simple as swapping out the clusters and putting a tach wire and power on the gauge? thanks for the help!!!! Anything else i should look out for
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1970 chevelle 1971 blazer 1972 c20 custom camper 1931 ford A coupe. |
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#2 |
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Join Date: Feb 2012
Location: Ruskin Florida
Posts: 4,559
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Re: Tach dash question, need help.
The tach should have a 6 or 8 on the back of it.
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#3 |
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Location: auburn ma
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Re: Tach dash question, need help.
hmmm... looked all over.. did not see any stamp or tag... could be under the
"tin" ?
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1970 chevelle 1971 blazer 1972 c20 custom camper 1931 ford A coupe. |
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#4 |
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Location: Victoria, B.C
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You don't have to fully install it to test it.
(note: on the back of the tach they originally had a '6 cyl' print they put on it or a GM part number....but this might be worn off now) Do the following to test the tach: First.....Review the back of the tach...there should be an insulated (2) prong connection in the back/centre with a clear 12V (+) indicator and a Coil or 'signal' connector. The indicators for these should be stamped into the casing. (note: normally these connectors are at 90° to one another the way they are orientated and this would be what the tach harness normally plugs into) Next: Run a hot/positive from your battery to the 12V (+) prong/connector. Next: Run a wire from the - (negative) side of your coil to the 'Coil' (signal) prong connector Next: Run a ground wire from your block to the metal casing of the tach. Check all of these connections to make sure they are solidly connected and well insulated from one another. Start up the truck and check the readings and rev the truck to see how much gain/rpm reads out. All Good Coley
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....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500 |
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#5 | |
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Location: auburn ma
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Re: Tach dash question, need help.
Quote:
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#6 |
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Join Date: Mar 2011
Location: Elizabethtown, Kentucky
Posts: 322
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Re: Tach dash question, need help.
You need to make sure the printed circuit board is for a tach. A non tach circuit board does not have a place for the 12+ and coil wire to feed through and will not stretch enough per say to accomodate the tach under it.
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#7 |
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![]() Join Date: Jul 2008
Location: auburn ma
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Re: Tach dash question, need help.
YES I have a whole cluster now that is complete.
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1970 chevelle 1971 blazer 1972 c20 custom camper 1931 ford A coupe. |
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#8 |
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Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: Tach dash question, need help.
Plug it in. If you have HEI it'll be hit or miss. I'd stick one of those cheap but highly-accurate tach/dwell/volt/etc meters on it to compare and make sure it's accurate. That'll also ensure you have the right 6/8 cyl tach.
In the event the tach is wrong, they're not that expensive as a repro. You already have the cluster, PCB, all of that. I bought this one from Amazon for 25 bucks: ![]() The scale also shows what it -would- be for a 6 cyl, so let's say it doesn't match the 8 cyl scale but does match the 6, you know what you've got. I noticed my multimeter also has a Hz setting but was unable to get a useful signal.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#9 |
Registered User
Join Date: Feb 2012
Location: Ruskin Florida
Posts: 4,559
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Re: Tach dash question, need help.
Yep and you can sell the 6cyl tach here easy in the event that it is 6cyl.
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70 swb 4x4 406sbc 700r4 203/205 d60/14blt locker yadda yadda http://67-72chevytrucks.com/vboard/s...88#post6935688 Yeller 72 Blazer 2wd conversion project "No Daggum Money" http://67-72chevytrucks.com/vboard/s...d.php?t=550804 LS1-T56 3.73 LSD super budget build Blanco-2014 Sierra SWB https://67-72chevytrucks.com/vboard/...d.php?t=810350 |
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