Re: Dead tach....need tach filter?

by dynchel Sat Aug 02, 2014 9:22 am

This may sound bad but since your car has a stock car vib, why not just get a big auto meter monster tach and call it a day?

by Mcarlo77 Sat Aug 02, 2014 9:24 am

Interesting info...first time anyone has actually explained the differences other than the style of the face. So...I've got a '73 style tach with a mint face plate but, no circuit board and a '75 tach with a corroded face but circuit board. Is it correct to assume a person could swap the circuit board from the '75 (HEI) to the '73 tach and it would work with either the HEI or points?

by 77mali Sat Aug 02, 2014 9:54 am

The Tachman uses a newer "3 prong board" from what I understand, although, unless you've bought one- you can't find a pic of it online & he covers it up in the picture on his website. I'm assuming he's trying to keep that info exclusive as no one else seems to be doing this conversion. I am planning to use him once the time comes if mine gives me grief. Worth the $$ IMHO. He's a small shop so I think he's prob overwhelmed with business sometimes. (No excuse for bad customer service though!)

On another note- if you look at Chris' video, when he gets in to turn the key the Tach needle reads what I presume to be curb idle speed. The needle goes down to zero when the key is turned and back up when the car is on again. If anyone is looking for these used online- that's needle position off the zero is a good sign. If the needle reads zero off the car it's probably got issues.

by Oldschool454 Sat Aug 02, 2014 10:31 am

dynchel wrote:This may sound bad but since your car has a stock car vib, why not just get a big auto meter monster tach and call it a day?

This isn't actually on my car. It's on my dad's car. Which is also a 76 Laguna. He has all of his factory comforts still. No roll cage, original dash, heat, a/c, all that stuff...So he wants to keep the original dash look.

by Oldschool454 Sat Aug 02, 2014 10:37 am

77mali wrote:The Tachman uses a newer "3 prong board" from what I understand, although, unless you've bought one- you can't find a pic of it online & he covers it up in the picture on his website. I'm assuming he's trying to keep that info exclusive as no one else seems to be doing this conversion. I am planning to use him once the time comes if mine gives me grief. Worth the $$ IMHO. He's a small shop so I think he's prob overwhelmed with business sometimes. (No excuse for bad customer service though!)

On another note- if you look at Chris' video, when he gets in to turn the key the Tach needle reads what I presume to be curb idle speed. The needle goes down to zero when the key is turned and back up when the car is on again. If anyone is looking for these used online- that's needle position off the zero is a good sign. If the needle reads zero off the car it's probably got issues.

I'd be curious to find out either where he gets his, or if it's off of another car even. May have to dig some more online for info. If I hadn't just spent 450.00 on the dash I may have thought about having it done by him. And in Chris' video, how his tach was acting is exactly how mine was acting when it was working. I'm gonna dig some more and I'll post anything if I find out more.

by Mcarlo77 Sat Aug 02, 2014 10:40 am

I interpret that 3-prong conversion as nothing more than putting a '75 style board in place of the 4-prong tach boards on the '73/'74 versions...which, again begs the question of whether the internals of the tach are the same?

I would tend to agree with you, Paul, on the assessment of the position of the needle with no power to the tach. The NOS one I found last winter is sitting at around 2000 rpm.

by Mcarlo77 Sat Aug 02, 2014 10:44 am

Regarding the question of where Gary the Tach Man gets his boards, I'm sure he has a source who makes the printed circuits for him. I was in the business of supplying circuit board fabricators with supplies and you could find a smaller shop to do small runs. Of course, it's more expensive than if they were mass produced...so, I do understand the cost Gary requires to do this work.

by g3chevy / Mr Pontiac Sat Aug 02, 2014 10:46 am

I attempted to change out circuit boards in the past from a 75 tach to a 73 tach but then realized because the 73,74 tachs have the 4th post on the back and there is no 4th hole on the 75 tach circuit board then it was obvious I couldn't do the swap. There may be some board level repair shops still around that you can ship your circuit board to and have it repaired. I've used companies like this in the past to repair other electronics with good results. I also have contacted the Tach Man and found his customer service demeanor less than helpful. I'm sure he does a good job, but if you did have an issue after the sale it may not work in your favor is the vibe I get. Good luck.

by dynchel Sat Aug 02, 2014 11:07 am

www.redlinegaugeworks.com

This is who the magazines always pimp for this kind of work.

by 77mali Sat Aug 02, 2014 2:01 pm

dynchel wrote:www.redlinegaugeworks.com

This is who the magazines always pimp for this kind of work.

Good info! Although- I saw Jay Leno's mug on the bottom of the page ...
That almost always means a second mortgage lol!

by Oldschool454 Sat Aug 02, 2014 3:07 pm

g3chevy wrote:I attempted to change out circuit boards in the past from a 75 tach to a 73 tach but then realized because the 73,74 tachs have the 4th post on the back and there is no 4th hole on the 75 tach circuit board then it was obvious I couldn't do the swap. There may be some board level repair shops still around that you can ship your circuit board to and have it repaired. I've used companies like this in the past to repair other electronics with good results. I also have contacted the Tach Man and found his customer service demeanor less than helpful. I'm sure he does a good job, but if you did have an issue after the sale it may not work in your favor is the vibe I get. Good luck.

Do the other prongs line up though? They look like they would but I don't have one for comparison. I need to do the opposite. Go from 73 tach circuit board to a 75 or 76. I wonder if you could do that swap and if it would work ok?

by g3chevy / Mr Pontiac Sat Aug 02, 2014 3:12 pm

I haven't tried the reverse swap but the prongs do line up exactly the same on both versions.

by Hawk03 Sun Aug 03, 2014 10:14 pm

Everything I've read is that adding a filter will allow the pre-HEI distributers to work with the points systme tachs. Will any filter work and is the solution this easy? I've found this one for a Corvette so I would think it would work.

http://www.ecklerscorvette.com/corvette-tachometer-filter-original-barrel-style-1975-1989.html

by Mcarlo77 Sun Aug 03, 2014 10:30 pm

Looks pretty close to the one I removed from a '75 Laguna.

tach) - Dead tach....need tach filter? - Page 2 Tachga10

by Oldschool454 Mon Aug 04, 2014 7:50 am

Hawk03 wrote:Everything I've read is that adding a filter will allow the pre-HEI distributers to work with the points systme tachs. Will any filter work and is the solution this easy? I've found this one for a Corvette so I would think it would work.

http://www.ecklerscorvette.com/corvette-tachometer-filter-original-barrel-style-1975-1989.html

I thought it was the opposite. The filter allows the tach to read the hei waves. That's why they use then on a lot of gm cars past 74?

by Hawk03 Mon Aug 04, 2014 7:58 am

Oldschool454 wrote:
Hawk03 wrote:Everything I've read is that adding a filter will allow the pre-HEI distributers to work with the points systme tachs. Will any filter work and is the solution this easy? I've found this one for a Corvette so I would think it would work.

http://www.ecklerscorvette.com/corvette-tachometer-filter-original-barrel-style-1975-1989.html
I thought it was the opposite. The filter allows the tach to read the hei waves. That's why they use then on a lot of gm cars past 74?

We're on the same page, my thoughts didn't type out very well. Adding a filter should allow the 73/74 tachs to work with an HEI system. Here is another filter for a Corvette and states it cures "dead tachs." I don't know if there are any difference between the other link I posted.

http://www.rodneydickman.com/CorvetteTachFilter.html

When searching for Chevelle the only link that comes up for a filter is this one:

http://www.ecklerschevelle.com/tachometer-adapter-for-classic-instruments.html

Is there any difference between this one and the one for the Corvette?

by Hawk03 Mon Aug 04, 2014 8:02 am

Mcarlo77 wrote:Looks pretty close to the one I removed from a '75 Laguna.

Cool, That is the cheapest I've seen them. Some of the name brands seem to go for around $80 or so.

by SSTOOLMAN Mon Aug 04, 2014 10:31 am

My 1973 tach doesn't register, the guy I got it from swears it worked in his 73, he had a points system... I have a HEI. I took a chance and just ordered the. $29.99 one from Ecklers http://www.ecklerscorvette.com/corvette-tachometer-filter-original-barrel-style-1975-1989.html I should get it next week. I will let you know if it solves the problem.

by Hawk03 Mon Aug 04, 2014 12:23 pm

SSTOOLMAN wrote:My 1973 tach doesn't register, the guy I got it from swears it worked in his 73, he had a points system... I have a HEI. I took a chance and just ordered the. $29.99 one from Ecklers http://www.ecklerscorvette.com/corvette-tachometer-filter-original-barrel-style-1975-1989.html I should get it next week. I will let you know if it solves the problem.

Awesome! Thanks for taking the chance. I hoping that is all that is needed to run these tachs.

by Oldschool454 Mon Aug 04, 2014 1:49 pm

SSTOOLMAN wrote:My 1973 tach doesn't register, the guy I got it from swears it worked in his 73, he had a points system... I have a HEI. I took a chance and just ordered the. $29.99 one from Ecklers http://www.ecklerscorvette.com/corvette-tachometer-filter-original-barrel-style-1975-1989.html I should get it next week. I will let you know if it solves the problem.

Yes, please let us know. Keeping my fingers crossed for that it fixes yours.

by SSTOOLMAN Fri Aug 08, 2014 10:32 pm

SSTOOLMAN wrote:My 1973 tach doesn't register, the guy I got it from swears it worked in his 73, he had a points system... I have a HEI. I took a chance and just ordered the. $29.99 one from Ecklers http://www.ecklerscorvette.com/corvette-tachometer-filter-original-barrel-style-1975-1989.html I should get it next week. I will let you know if it solves the problem.

Well guys I got the filter and hooked it up and...... nothing, it didn't solve the problem, I thought it might work because I know my tack is not completely dead, with the key off the needle reads about 1000 rpm, when key is on it drops to zero. I have seen working tacks do this.
Mr tach man maybe the only solution. Evil or Very Mad

Ill see if I can send it back... unless someone from the forum wants to try it?

by Oldschool454 Fri Aug 08, 2014 11:21 pm

dang! That sucks. Yes, my tach does the same. Drops to zero with ignition on. So I think that means it's getting power at least. Maybe just no signal? hmmmm....what to do. Never thought a tach would be this horribly complicated to diagnose.

by 77mali Sat Aug 09, 2014 8:23 am

Usually when something "kind-of" works it may need a ground wire. IDK what terminal on the tach you'd put it on but it would only be a matter of attaching it to the frame & there are at least a couple of grounds under the dash that you could ad another wire to. You could try and touch each terminal to see if you get any reaction while the car is running. Just a thought.

by Oldschool454 Sat Aug 09, 2014 1:26 pm

77mali wrote:Usually when something "kind-of" works it may need a ground wire. IDK what terminal on the tach you'd put it on but it would only be a matter of attaching it to the frame & there are at least a couple of grounds under the dash that you could ad another wire to. You could try and touch each terminal to see if you get any reaction while the car is running. Just a thought.

Good idea. I'll try that. I already know what terminal is ground so should be easy to check.

by 77mali Sat Aug 09, 2014 1:38 pm

Well- don't keep it a secret!
lol!

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