Need Help With '75 Tach (PICS)
Thread Starter
Race Director
Joined: Feb 2006
Posts: 12,239
Likes: 19
From: Chino CA
Need Help With '75 Tach (PICS)
My Vette is a 1974...I'm re-doing the whole interior...
Long ago I switched to HEI ignition with no cable drive...so I recently bought a tach from a 1975 Vette.
So here are a couple questions...
1) How can I test it before I put it in the dash ?
2) Will it bolt directly in ?
3) I was told it should have one wire that goes to the "Tach" terminal on the dizzy and one ground - but I see it has a 3 prong connector and a ground. What do I need to do with the 3 prong ???
LOL...
4) Where can I get the plastic "bucket" (blue outside, black on the inside) that it sits in....mine is cracked.
Thanks in advance !!!
The Tach
The back w/connector
Long ago I switched to HEI ignition with no cable drive...so I recently bought a tach from a 1975 Vette.
So here are a couple questions...
1) How can I test it before I put it in the dash ?
2) Will it bolt directly in ?
3) I was told it should have one wire that goes to the "Tach" terminal on the dizzy and one ground - but I see it has a 3 prong connector and a ground. What do I need to do with the 3 prong ???
LOL...4) Where can I get the plastic "bucket" (blue outside, black on the inside) that it sits in....mine is cracked.
Thanks in advance !!!
The Tach
The back w/connector
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
You can test it easily without installing in the car. In the pic above connect:
1) "Pos" to the alternator stud (the one with the heavy gauge red wire)
2) "Neg" to any ground. The clamp holding the brake reservoir lid works fine.
3) "Tach" to the tach terminal on the HEI.
Start the engine and the tach should work. If the needle jumps around you will need a tach filter, most of the vendors carry them.
1) "Pos" to the alternator stud (the one with the heavy gauge red wire)
2) "Neg" to any ground. The clamp holding the brake reservoir lid works fine.
3) "Tach" to the tach terminal on the HEI.
Start the engine and the tach should work. If the needle jumps around you will need a tach filter, most of the vendors carry them.
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