Topic: Tacho problem resolved
in Forum: C3 Electrical
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Thanks to all those that supplied ideas and places to get bits. Just to recap there was no filter for the tacho when I bought the car, fitted one but it still didn't work, circuit board looked good but bought one anyway. (Theo thanks for the contact) Fitted circuit board switched on the ignition watched the needle zero, started the engine and watched the needle do NOTHING!. Much head scratching later and for no other reason than "sod it" I took the filter out to see what would happen. Ignition on, needle on zero, start the engine and hey presto it works fine, rock solid. So now the dash can start to go back in.


white 79|COLOR=NAVY| |/COLOR|
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No worries, glad you sorted it! Just one word of warning though, several people say that you need the tacho filter to protect the board from eventually being fried. However, several people also say you don't need it!
I decided to be on the safe side and keep my filter in line. If you look at the filter you may just find that the wires have broken as they go into the epoxy bit on the end. If that's the case, you can actually break that bit off to give you some spare wire sticking out, and resolder new wires in.
Alternatively, Ecklers have literally just started selling reproduction filters if you fancy a new one. Quite good timing!
Whether you think they protect the board or not, they definitely stop the needle from bouncing around, which could get quite irritating. Oh, and if you do fit one, make sure it's grounded via its mounting tag. (That's why they are bolted to the inlet manifold as stock)
I decided to be on the safe side and keep my filter in line. If you look at the filter you may just find that the wires have broken as they go into the epoxy bit on the end. If that's the case, you can actually break that bit off to give you some spare wire sticking out, and resolder new wires in.
Alternatively, Ecklers have literally just started selling reproduction filters if you fancy a new one. Quite good timing!
Whether you think they protect the board or not, they definitely stop the needle from bouncing around, which could get quite irritating. Oh, and if you do fit one, make sure it's grounded via its mounting tag. (That's why they are bolted to the inlet manifold as stock)
|IMG|http://www.nottingham.ac.uk/~eaztl1/images/vette_4_sig.jpg |/IMG|
Red 1980 350 auto w/ quickshsift
Edelbrock intake / carb
Crane Fireball cam
0 - 60 6.3s

HOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
My 79's tach drifts at about 7gs at idle and buries as sson as rpm raises from idle, I'm thinking it's the tach board as well. What were your symptoms?
PS - I have the orifinal filter connected.
Thanks
Luke
PS - I have the orifinal filter connected.

Thanks
Luke
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Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
kind of makes you miss the good ole days with a tach drive cable..
|UPDATED|5/18/2004 11:11:48 AM (AZT)|/UPDATED|
|UPDATED|5/18/2004 11:11:48 AM (AZT)|/UPDATED|
Theo,
The filter I put in was one from ecklers, with it fitted the tach won't work, remove the filter and all appears fine. I'll just have to see how long it all holds together for and hope the new circuit board survives. At least I will know where to start next time if it does fail.
The filter I put in was one from ecklers, with it fitted the tach won't work, remove the filter and all appears fine. I'll just have to see how long it all holds together for and hope the new circuit board survives. At least I will know where to start next time if it does fail.
white 79|COLOR=NAVY| |/COLOR|
Oh, sorry misunderstood you. So you have a new board and when you drop the new filter in, the tacho ceases to work, right?
Sounds as though the filter from Ecklers is duff. If what you say is true, I'd be trying Ecklers for a replacment filter that actually works. At least that might help your board to last a little longer.
You can test the filter's continuity with a multimeter, it should have a resistance of about 15 to 20 K ohms.

Sounds as though the filter from Ecklers is duff. If what you say is true, I'd be trying Ecklers for a replacment filter that actually works. At least that might help your board to last a little longer.
You can test the filter's continuity with a multimeter, it should have a resistance of about 15 to 20 K ohms.

|IMG|http://www.nottingham.ac.uk/~eaztl1/images/vette_4_sig.jpg |/IMG|
Red 1980 350 auto w/ quickshsift
Edelbrock intake / carb
Crane Fireball cam
0 - 60 6.3s
in Forum: C3 Electrical
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