Tachometer

[Jim Shepard]

I've always wanted to put a tach in my truck and now that it's 12V the possibilities are endless. However... I want something old school-looking that doesn't wind out to 8-9,000. Anyone know where I can get one that tops out at a more reasonable number - like 3-4,000 rpm? BTW - what is the maximum rpm's on these trucks?

[DJ194950]

Look on ebay for boat tachs, many are 4-5K max., some (very few are 6 v.).

Just make sure that they are for 6 cyl. or have the switch to change to 4-6or 8 cyl. if you still run 6 cyl.

Seems to me that you might be the truck I saw at Tim's BBQ several years ago with the old type hemi?? Might have been your friends, not sure you know-getting too old!

DJ

[Plymouthy Adams]

Weston is a brand to investigate

 

change that to WESTACH   I knew it was Wes something as I sent one to Young Ed long back NIB

 

another update...will BOLO at the swap meet this morning for example of TACHS available..this crowd would be ideal location to find such an animal in captivity..

Edited March 19, 2017 by Plymouthy Adams

[55 Fargo]

good luck on a 3-4 k Tach, and 6 volt too boot.

The diesel types are lower, but again not of any use.

I today bought this elcheapo $25 7000 RPM tach, setting the redline at 1/2 @3500 RPM.

Works great, it replaced my broken Sun Pro tach, which I need to send away for repairs, as it is vintage...

Engine dual carbs and exhaust big block warmed up and idling at 500 rpm.

Edited March 19, 2017 by Rockwood

[Young Ed]

7 minutes ago, Rockwood said:

good luck on a 3-4 k Tach, and 6 volt too boot.

 

Well I thought they were readily available from westach. However on their website I only see 4cyl and 8cyl models. Perhaps anyone wanting a 6v one could call them. 

[55 Fargo]

Yes I too looked around for a fair priced tach in the 4-5k range, but decided to buy an elcheapo locally.

With the USD/CDN dollar exchange, have not bought many goods from the US in a while.

I can understand why nobody really wants an 8-10 k tach, I can live with a 7k tach....

[Desotodav]

My favorite tach is the one installed in DD...

 

[wallytoo]

what i installed in my 1.5-ton.....12v, 6 cylinder version.  inexpensive, but i like it because when the needle is up, i'm close to redline, so it works for my parameters.

[Alshere59]

 WESTACH has them listed just go to the single gauge menu. As mentioned before give them a call to see iy they have what you need.

Model:    3CT53-2-6V
Price:      $143.65 
Tachometer 5,000 RPM, 3" round, std pt or mag ign, 1-1/2 & 3 imp, ( 3 or 6 cyl ) 6 volt positive/negative ground.

Model:    2CT33-6V
Price:      $124.65 
Tachometer 3,500 RPM, 2" round, std pt ign, 3 imp/rev ( 6 cyl ), 6 volt, pos or neg grd

Your second question you can decide after reading this. There are other threads as well just search the forums.

 

Al

[55 Fargo]

1 hour ago, Alshere59 said:

 WESTACH has them listed just go to the single gauge menu. As mentioned before give them a call to see iy they have what you need.

Model:    3CT53-2-6V
Price:      $143.65 
Tachometer 5,000 RPM, 3" round, std pt or mag ign, 1-1/2 & 3 imp, ( 3 or 6 cyl ) 6 volt positive/negative ground.

Model:    2CT33-6V
Price:      $124.65 
Tachometer 3,500 RPM, 2" round, std pt ign, 3 imp/rev ( 6 cyl ), 6 volt, pos or neg grd

Your second question you can decide after reading this. There are other threads as well just search the forums.

 

Al

Only 1 way to find out. I can tell you mine likes up to 3000 never been beyond, in my time on this engine.

In fact, its hard to rev her up beyond this point, cam profile obviously not conducive for much more on my engine.

Had the truck out early this morning, 2500 @60mph 2700 @65 mph, 3000 @71 mph, now my rearend is supposed to be a 3.23, but the RPM and tire size point to 3.55 on the RPM scale, i don't get it.....

 

[Alshere59]

Rockwood have you ever run a gps and compare it to your speedometer reading? That may help but you never know.

 

[Dennis46PU]

I have AutoMeter in my truck for all the gauges.  Over half of my gauges I got on ebay up for bid from a private party.  The only downside is you have to be 12v neg ground.  The tach will work with 4, 6, or 8 cylinder, just set the switches inside the housing.  My speedometer is easily calibrated anytime and has the electronic sender for GM that works perfect.  I only had to modify one piece of my park brake linkage to fit the sending unit.  Autometer has a huge selection of needle and face combinations.  I have antique beige in my truck but they can also be purchased in black if you want to go with that style.  AutoMeter has GPS speedometers, but they are overpriced IMO.

[55 Fargo]

4 hours ago, Alshere59 said:

Rockwood have you ever run a gps and compare it to your speedometer reading? That may help but you never know.

 

All the time, and its verified correct reads 50 mph for 60 mph.

Those calculators are not an exact science, so add windage and load and more RPM for a certain speed I suppose...

[Jim Shepard]

As I mentioned, my truck is now 12V. I like DD's tach. Anyone know anything about it?

[wallytoo]

6 hours ago, Jim Shepard said:

As I mentioned, my truck is now 12V. I like DD's tach. Anyone know anything about it?

i'm sure dav does.

[Desotodav]

45 minutes ago, wallytoo said:

i'm sure dav does.

Nup. I was just very impressed at the idea when Rob posted pictures of it in his DD build thread...

.... (post #128 on page 6 of that thread has more information).

I'd really like to (one day) install one the same as that in my blue truck. I'll have to show it to my gauge fella and see if he can find me a 6v tach from Westach!

I look forward to chatting with you again Jim at 'the Q'.

[wallytoo]

oh.  i thought that was yours.  i can't keep track of who owns what.

whoeverowns DD should know.

[55 Fargo]

On 3/19/2017 at 1:49 PM, Alshere59 said:

Rockwood have you ever run a gps and compare it to your speedometer reading? That may help but you never know.

 

So today for the umpteenth time, I spun the rear passenger tire, and counted the driveshaft turns, and it indicates 3.23.

Now my rpm at 60,65 and 70  MPH are higher than what any RPM calculator states it should be for a 3.23 with 28.2 inch tires.

Scratchin my head on this one...

[BobB]

Might that indicate that the gearing at the transmission end of the drive shaft is different than expected? I'm not up to snuff on these things, but it seems that there are two sets of gears between the engine and the tires.

[Merle Coggins]

Did you only turn one wheel? You will get a more accurate count if you turn both wheels equally. The best way to do that is with it on the ground, but then it's more difficult to count the turns when the truck is moving. Maybe mount a GoPro under the truck so that you can see the drive shaft and the tire. Mark both and  s l o w l y  drive forward. Then review the footage. May have to make multiple marks on the shaft, like every 90 degrees, to be able to determine the exact count.

Also, if you use the loaded radius of the tire to calculate the diameter you will get a more accurate calculation. Measure from the ground to the center of the axle, then multiply by 2 to get the diameter. You will find that to be slightly smaller than the diameter that you were using.

[55 Fargo]

2 hours ago, BobB said:

Might that indicate that the gearing at the transmission end of the drive shaft is different than expected? I'm not up to snuff on these things, but it seems that there are two sets of gears between the engine and the tires.

Its not an overdrive, but a Canadian T98 Acme heavy duty 4 spd, with 1:1 in 4th.

 

1 hour ago, Merle Coggins said:

Did you only turn one wheel? You will get a more accurate count if you turn both wheels equally. The best way to do that is with it on the ground, but then it's more difficult to count the turns when the truck is moving. Maybe mount a GoPro under the truck so that you can see the drive shaft and the tire. Mark both and  s l o w l y  drive forward. Then review the footage. May have to make multiple marks on the shaft, like every 90 degrees, to be able to determine the exact count.

Also, if you use the loaded radius of the tire to calculate the diameter you will get a more accurate calculation. Measure from the ground to the center of the axle, then multiply by 2 to get the diameter. You will find that to be slightly smaller than the diameter that you were using.

I dunno Merle, done it many times, different ways, the way you describe too.

I always get the same results, so maybe time to pull diff plate cover, and change up the lube too.

I guess I could blame the tach, but the old tach when working good gave the same reading for 60-65-70, so i dunno.

Now the RPM at those speeds are not bad, but they should read lower with a 3.23 rearend and 28 inch tires....

Thanx Guys

 

[55 Fargo]

Another possibility/scenario, clutch slippage slightly at higher speeds, wind velocity and resistance?

I have never notice my clutch slipping at any time though...

[55 Fargo]

 

[55 Fargo]

The guessing game is over.

its definitely a 3.23, as verified by OEM tag.

Perhaps the elchepo little tach is out a bit, no big deal.

My tires are P 235 75 15s, but stand only about 27.7 tall, so can add some RPM there too.

I have no trouble taking off in 2nd gear, which is 3.09, do not have to rev the crap put of the engine or nothing.

I do not think an overdrive with say .73 would work well with this rearend though, something like .85 overdrive would be about right....