IROCZman15

iTrader: (25)

I did a search and was surprised I didnt find anything on here. I guess there's not really much tech to it, but I was hoping someone had a trick or tip about it.


With my new 406 small block chevy engine setup my redline is wayyyy higher than what the oem dash tach has for yellow and red display. (my 1987 OEM camaro tach used to have yellow from 4,500-5,000 and then redline from 5,000-7,000) which was just unnecessary to look at now
(not my image/dashboard, but this is the tach I have)

but


So now that I am getting more used to seeing the tach needle in the 6,000 rpm range, I want my tach to not have any more yellow or red where it did from stock, which made sense for the TPI setup that didn't breathe at higher rpms like my new engine does. I took apart the dash and pulled out the tach from the cluster, hoping the yellow and red was just a sticker that I could peel part of it off. No luck, looks like it was a sticker, but then it is clear coated over at the factory. So I VERY PRECISELY blacked out the red and yellow above the 4,500-6,000 rpm range. then I taped off the area where the white hash marks would be and painted them in. it actually turned out really really nice and I was moments away from installing it......

UNTIL.....

I went to wipe off my fingerprints from the tach gauge face and whatever I had previously used that rag for was still in the rag fibers and it began to slightly smear the numbers that were on the tach.. not the ones I had just painted, but the actual oem 1987 dash number display. I was devestated. I touched it up as good as I could and it does look pretty good. but not good enough, you can see where the numbers started to fade/smeared around 40, 45, and 50.. so I stopped right there and didnt worry about finishing the white detail work on the numbers or hash marks, until I get a new plan, I just put it back in so i can drive the car tomorrow.





My new "red" redline display goal was accomplished and I now have a red-line only between 6,000-7,000 rpm on the tach face. I might be looking for a new tach and trying it again for a ultra clean look, making sure NOT to smear everything .. maybe



the other thought was that since the factory tachs are always off, maybe i could find a different tach that would fit into the dashboard cluster and still mount behind the trim panel? I know for a fact that the holley sniper display's tach is accurate, but it is tiny and will be hard to see while racing on the tiny holley LCD display , so i was really hoping to use the factory one (reworked) or one that is accurate and will fit INSIDE the dash cluster. NOT looking for any tach that would be bolted to teh interior in a clunky manner. thats not my style
but my question is, aside from doing my paint method above, and aside from ordering a new aftermarket tach, has anyone got creative and covered over (or removed) the yellow and red markings from their tach, to be more representative of their engine's actual redilne after a motor swap? or is everyone mostly just living with the old tach gauge face and the yellow and red?

paulo57509

There are gauge/instrument restoration places that can either restore the original gauge face or make custom faces. This can get a bit spendy, though.

TransamGTA350

iTrader: (2)

You may be able to use a v6 tach with a 6K redline. Either swap the faceplate over to your tach, or swap the circuit board from your tach to the v6 tach so it reads correctly. I haven’t done this myself, but I have heard of others doing it successfully.

IROCZman15

iTrader: (25)

that sounds like a viable option. way cool. thanks!

i'll look into it, but if anyone else has know-how on this option, please let me know!



sidenote- I "tested" my oem tach to see how much it was off, and it wasn't drastic, but is still certainly off

-I set the Rev limiter on my holley sniper handheld to 3,000 rpm and revved the throttle while in park and it started hitting the limiter when the oem tach showed about 3,200 rpm
- i then set the rev limiter to 5,000 and revved the engine and it went to right around 5,300 ish rpm.

so: if I keep this tach (or a cleaner re-painted crisp version of this exact tach display, I would want to shift right around 6,000 or 6,200 to stay in my powerband. with the current tach, I should probably force shift the car(when racing) when this tach reads 6,400-6,500 rpm...since it would probably be of and reading higher by about 400 rpm... thoughts?
- on my one and only shakedown 1/4 mile pass day before covid19 shut down the racetracks, I was shifting in the 5,700 range by looking at the oem tach.. which now I am learning, that was actually me shifting around 5,300 which is pretty low on my new engine's power curve. see dyno sheet numbers below. I had no intentions of killing the car on a brand new engine build back in early march, and was simply there for a shakedown of the new build.. but we all had no idea the tracks would be shut down for months .. and I would be stuck anxiously awaiting a day to drive the car properly/faster. hoping to get out to the track sooner than later this year once its allowed to re-open, but would like to have a great plan about when to shift and to have the tach display setup where I know i am shifting at the best possible moment

Tuned Performance

iTrader: (92)

See if Cajun tach ship can convert the v6 to v8

IROCZman15

iTrader: (25)

what timing! I actually just sent him a PM about 2 minutes ago!!
username "gcj280" says he was last online here about a week ago... so that is promising!
I searched the forum for v6 tach and was reading some threads.. i quickly became aware of him and that he builds/repairs/perfects tachs so i sent him a message. thanks Tuned

QwkTrip

iTrader: (22)

My '89 V6 tach (Firebird) has a 6K rpm redline on an 8K rpm scale. I'll bet it's as simple as finding a V8 tach with the same numbers pattern and swapping over the electronics to the V6 tach.

I have two different V8 tachs that came in 140 mph gage pods. One has a 5500 rpm redline with the same numbers pattern as my V6 tach. The other has a lower redline with a 6K rpm sweep and the number pattern is totally different. So apparently not any old V8 tach module will do.

I just kept my V6 tach and recalibrated it for a V8. You've got to have nerdy friends with a waveform generator to do that job though. I know a crap load of nerdy people and I've only known one guy in my life that had one at home.

QwkTrip

iTrader: (22)

That engine is still carrying power at 6400 rpm where the dyno sheet stops. I'd rev it 500 rpm above that and see whether it runs out of breath.

gcj280

iTrader: (15)

Hey Guys. I'm still around. I have a few spare tachs I can convert for you. I'll send you some info in a PM.

Thanks! Greg

cmm7v3

I wish I could cleanly modify the tach in my 92, the engine in it revs to 8k before fuel cut. I just have to watch and shift when the needle drops off the tach.

IROCZman15

iTrader: (25)

thats wild, shifting when the needle is maxxed out.

I got in contact with Greg at cajun tach shop and he is setting me up with an awesome re-calibrated V6 tach which will have a 6,000 redline, perfect for my engine's power curve. !

as a bonus, it comes with an 80 psi oil gauge, opposed to my current tach that has a 60 psi max. my oil pressure shows higher than the 60 psi on my current setup, so this will be great. actually, under WOT my numbers are in the 70's and 80's (see the 4th column of my dyno sheet above for oil pressure), so this will be great.
----I am wondering if I will need a new oil pressure sensor though? or does the sensor not care about what gauge it is connected to and just shows a reading, but now my gauge will have a larger range??

cmm7v3

I'm not sure where the stock oil pressure sender stops, but I know on cold starts my gauge is buried past 60 psi.

IROCZman15

iTrader: (25)

I installed the new tach from Cajun Tach Shop a few days ago and it is perfect. It was the V6 camaro style which does have a 6,000 rpm redline..which is perfect for my setup. It also has the 80 psi oil pressure gauge. I purchased an 80 psi oil pressure gauge from advanced auto parts for a few bucks and installed it. the gauge reads correct, and the recalibrated tach works great. obviously the needle reacts slightly slower than the holley sniper digital handheld display, so its not near in perfect sync for the photos. but it is damn accurate..and a million times better than my oem tach that was off by several hundred rpms

total success. Thanks for the help guys, and thanks to Cajun Tach Shop for the awesome upgrade.

TransamGTA350

iTrader: (2)

Very Nice!