tach question

[oldtrux]

hi all,i am refurbing my gauge cluster and want to add a tach.my question is repop vs finding a good factory tach?i have a feeling the answer is as always factory is better but i would like to listen to personal experience.i have a 66/ 283 with pertronix dizzy.thanx for any help...dan

[frankslagoon]

I got a indash from classic parts for 189.00 5k read out looks good. I like it. I'm using an Accel conversion in the dist. I think they are the same thing as yours. My trk is a 63 but the tachs are the same the cat. says 63 thru 66.

[oldtrux]

thanx for the info frankslagoon!i think i will go with that tach also.appreciate the help

[ray_mcavoy]

Yes, the reproduction tach like frankslagoon used will probably be the easiest way to go.


The original tachs aren't all that easy to find and you have to make sure you're getting the right one for your application.

From the face, the 60-66 tachs all look about the same but the 60-62 version just had the meter movement in the dash and used a separate transmitter box.
The 63-66 tachs have built-in electronics (no more transmitter box) but there were at least 3 different ones:

GM #3852111 for 6-cyl engines.
GM #3839947 for V8 engines without transistor ignition.
GM #3885480 for V8 engines with transistor ignition ... I believe that option was only available in 66 medium/heavy duty trucks.

As far as I know, the reproductions are copies of the GM #3839947 V8 tach. They're correct for 63-66 but will fit 60-66 Chevy full gauge clusters.

[Joe Pass]

I also used the Classic Parts tach conversion but I'm not completely satisfied...That being said I ran into a issue with it not being close to accurate. My first one wouldn't read so they replaced it and the second one isn't accurate. I worked with the Classic's tech and they said sometimes an aftermarket HEI doesn't send the right signal and reads half of what it should. I have an MSD HEI so I contacted them and they suggested a resister that didn't help either. I tried a new HEI from GM and that failed to read correct also. They have a filter available and even though they say its not need for HEI, they suggested that I try it. I ordered it at the tune of $27 and it made no difference.
Just for the record I have been installing aviation navigation and worked with a lot of instrumentation and I'm fully aware of proper installation and grounding etc..

[Joe Pass]

I would like to know if anybody else has experienced my problem because its useless as a tach. A Google search led me to a Chevy forum with another person with the same problem but the thread was old and with no response.
I bought a retro column mount Tach and its fine. I wish I did this in the first place because of the hassle...
Sorry to rant but beware of this issue..

[oldtrux]

thanks for the heads up joe pass!i'll stay tuned for more responses!now i'm confused as ever lol

[Joe Pass]

Originally Posted by oldtrux

thanks for the heads up joe pass!i'll stay tuned for more responses!now i'm confused as ever lol

Sorry for that....I'm just getting no help from Classic and Countrparts who makes the Tach in Orange Ca. I tried to contact them through the internet but they have no online tech or customer support. The tech at classic really had little to offer so I'm still looking for answers and would hate to see anyone else get stuck, but Hey, it looks cool.

[Joe Pass]

Here Is some pictures

[oldtrux]

wow!your expertise is obvious!beautiful looking cluster.hope mine turns out half that nice!

[Joe Pass]

Originally Posted by oldtrux

wow!your expertise is obvious!beautiful looking cluster.hope mine turns out half that nice!

Thank You

[frankslagoon]

Joe. I'm lookin at the paperwork for the classic tach. manufactured by counterpart automotive but no contact info. I used it on a breaker type and then converted to accel system. both seem to read pretty good. I did have a issue. when I tightened the mounting nuts to the backing plate the little ground strap on the back of the tach kinda pushed in to the tach housing and caused a short in the circuit board. I had to place a washer on each stud to hold the backing plate off. a pop rivet washer was enough. The tach wouldn't read at all. drove me nuts. so it's sure not an old stewart-warner but seems to be workin good now.

[Joe Pass]

Originally Posted by frankslagoon

Joe. I'm lookin at the paperwork for the classic tach. manufactured by counterpart automotive but no contact info. I used it on a breaker type and then converted to accel system. both seem to read pretty good. I did have a issue. when I tightened the mounting nuts to the backing plate the little ground strap on the back of the tach kinda pushed in to the tach housing and caused a short in the circuit board. I had to place a washer on each stud to hold the backing plate off. a pop rivet washer was enough. The tach wouldn't read at all. drove me nuts. so it's sure not an old stewart-warner but seems to be workin good now.

Thanks....I did the washer trick to make sure the GND tab would make a clean contact also....I did wiggle the tach housing while running in the driveway and the tach droped off and almost didn't read again until I tapped on it.
I will post my phone call results asap

[ray_mcavoy]

Joe ... have you tried hooking up the reproduction tach to a points ignition? Or to an electronic ignition system that doesn't have a variable dwell like HEI does?

I'm thinking the accuracy problem might be due to the circuit in the reproduction tach not being compatible with the variable dwell. And a factory tach might have the same issues ... I've never tried hooking one up to HEI to know for sure.

If that's the case, the reproduction tachs might still work okay with fixed-dwell "points eliminator" type electronic ignition conversions like Accel and Pertronix Ignitor I.

[Joe Pass]

Originally Posted by ray_mcavoy

Joe ... have you tried hooking up the reproduction tach to a points ignition? Or to an electronic ignition system that doesn't have a variable dwell like HEI does?

I'm thinking the accuracy problem might be due to the circuit in the reproduction tach not being compatible with the variable dwell. And a factory tach might have the same issues ... I've never tried hooking one up to HEI to know for sure.

If that's the case, the reproduction tachs might still work okay with fixed-dwell "points eliminator" type electronic ignition conversions like Accel and Pertronix Ignitor I.

I haven't tried a points distributer....I never thought to save any after HEI came out....
That would at least be worth a test just to rule out HEI issues. Classic claims its compatible with HEI so I will contact The Truck and Car Shop in Orange, Ca. after the weekend. Its my understanding that its made or sold under their Counterpart name. The website has no contact option but I'll try calling them direct. Thanks for the idea and sorry to have hijacked this thread....Joe

In the photo I'm spinning the engine at 2300 and this is the highest reading I have seen

[Joe Pass]

Called for tech support 3 times in the last 2 days at the "Truck and Car shop" where the Tach is distributed as a CounterParts item and received no return call. Only contact is a order number 1 800-243-8947 where they took my contact info and the nature of my call and said they will give them (tech) the message. In todays interactive world you would think emailing Tech support or even placing a order online would be preferred. I purchased plenty of restoration parts at the GoodGuy's shows from them over the years but the website isn't up to Classics Parts site standard's.
Sorry "oldtrux", I was hoping this helped but I its my problem and I will continue to work on a solution. Coming up I'm installing a clock in the panel so I will have the Tach removed again and will test it as Ray_mcavoy suggested...Joe

[Micmac]

Joe, what clock are you going to install? I remember reading somewhere, could've very well been here that an older Volvo station wagon clock fit like a glove. As was previously stated, you do beautiful work. You might could have a supplemental income at retirement! Thanks for all your comments.
Pete

[chevyrestoguy]

I have heard that some of the repop tachs are hit or miss. If you don't hear any good info from Counterparts, then maybe a call to a professional speedo shop like Hollywood Speedometer or United Speedometer in Riverside would be helpful. Don't be fooled by their name, they fully calibrate and service all instruments. They maybe be able to give you some solid advice or offer a service where they'll calibrate your current tach to work with your ignition. It may be something as simple as a calibration or the addition of the correct resistor. If you're reading too low, you may be OVER-resisted, if that makes any sense.

I asked the counter guy at the Truck Shop a couple of years ago if their tach was HEI compatible, and he told me no. I like HEI ignitions, so I was going to have an old 5K Sun tach I had laying around converted by Williamson's to modern internals that were compatible with my ignition. I never got around to it because another member theastronaut (his name is John Glenn) had a custom 10K tach made by Jason Wilson at Greenback Decal that looks 100% factory. I liked it so much that I had Jason make me a 7,000 rpm tach and it looks great. I'm still wiring my truck, so I have no info on how well it performs. Jason is a smart guy, and I'm certain that it'll be just fine. If you look at theastronaut's build thread, you'll see what the tach looks like.

[Joe Pass]

Originally Posted by chevyrestoguy

I have heard that some of the repop tachs are hit or miss. If you don't hear any good info from Counterparts, then maybe a call to a professional speedo shop like Hollywood Speedometer or United Speedometer in Riverside would be helpful. Don't be fooled by their name, they fully calibrate and service all instruments. They maybe be able to give you some solid advice or offer a service where they'll calibrate your current tach to work with your ignition. It may be something as simple as a calibration or the addition of the correct resistor. If you're reading too low, you may be OVER-resisted, if that makes any sense.

I asked the counter guy at the Truck Shop a couple of years ago if their tach was HEI compatible, and he told me no. I like HEI ignitions, so I was going to have an old 5K Sun tach I had laying around converted by Williamson's to modern internals that were compatible with my ignition. I never got around to it because another member theastronaut (his name is John Glenn) had a custom 10K tach made by Jason Wilson at Greenback Decal that looks 100% factory. I liked it so much that I had Jason make me a 7,000 rpm tach and it looks great. I'm still wiring my truck, so I have no info on how well it performs. Jason is a smart guy, and I'm certain that it'll be just fine. If you look at theastronaut's build thread, you'll see what the tach looks like.

Thanks for the heads up on some options on tachs....I don't think I will get the answers from the "Truck Shop" or anyone else selling them, but its therapy to haunt them about it ....lol. Your also right about being "over resisted" compared to a "high" reading.
About the clock, yes its a Volvo clock and the seller has more for sale, $10 plus $4 shipping. Its made by VDO and looks like a good fit after modifying the lens and bezel. I bought my clock on eBay and here is a current listing of one he is selling "Volvo-240-260-760-780-Instrument-Cluster-Quartz-Clock-OEM-/121552369756"
If you cut and paste the above link on eBay search it will come up with 3 for sale.
I found this out on a search here on this forum but I failed to remember his name and credit him on this info . Here is some photos of the one I have received...Joe

[Joe Pass]

I also will do a detailed clock install with some photos to share but its on the rear burner for a bit, I will jump on it as soon as I can.

[Micmac]

Thanks Joe, I anxiously await your documentary!

[yelmer]

if you use the factory style tach with the pertronix it will not read right . I had to convert mine to new electronics .works good now .

[Joe Pass]

Its all over the map on what ignitions and tach combinations will work...but what's funny is my $10.00 Sunpro test tach works on all my ignitions from points to HEI and Pertronix accurately

[chevyrestoguy]

Originally Posted by Joe Pass

Its all over the map on what ignitions and tach combinations will work...but what's funny is my $10.00 Sunpro test tach works on all my ignitions from points to HEI and Pertronix accurately

Joe, that is so true! It's especially frustrating when you're trying to do it right, and that dumb old Sunpro tach works better than anything else.