Build a tachometer for a 4bta Cummins

[isb cornbinder]

I wanted a mechanical tachometer drive for the Cummins 4bta that will power my son's 1952 IHC pickup. I bought a Cummins valve cover with an oil fill port to replace the front cover oil fill port.
I first cut the oil filler to reduce it to a shape that could be machined. I nest made a drive adapter to fit the injection pump drive and convert to a Stewart Warner tach drive. All of the pieces were fitted together then fitted to the front engine cover.
Finally the test.

 

[ADSR]

Well done, Sir. I bet you could sell a tone of those over at the 4bt forum. I'm a cummins conversion junky as well.

 

[homebuilt burner]

Not to question your build, but does it run at engine speed because the injection pump is only half engine speed? I am maybe assuming the ratio/right angle adapter has the step built into it.

A very clean looking adaptation.

 

[isb cornbinder]

This tachometer should be driven at cam speed. The injection pump runs at half crank speed, like the cam. The S-W 90 degree angle drive is 1-1.
There is no practical reason to have a tachometer in this application. The 4bta is governed to 3250 rpm. These old school tachometers like to give a bouncing needle reading and may less accurate. It is nothing more than a novelty gauge and something I can do . I have a 6 inch diameter Stewart Warner zero to 250 rpm tachometer. The tachometer clock display is counter clockwise. I am building a narrow flat leather belt drive for this tachometer and it will be mounted on my 1932 Ruston Hornby single cylinder Diesel.
The belt drive runs off a split pulley on the external cam shaft. The belt loading will be contained in a driven unit and the tach will be driven by an independent short open flex from the belt driven thingee.
I found the pictured crank deflection meter on Craigslist. It is made by Ruston Hornsby and is to be used when fitting the crankshaft to the engine.
The SMITHS tachometer is a real revolution counter. There is a mechanical odometer display that is driven by the input shaft. The internal clock spring is wound by the input shaft. The clock display is for timing the length of measurement of speed. This was truly "revolutionary" at the time.

(example, not mine)
I bought this CLPIIER belt lacing machine on eBay and the seller sent a second machine that is in need of a minor fix.
I will probably not use this machine and do a hand lace for what I think is a softer look.

 

[isb cornbinder]

Well done, Sir. I bet you could sell a tone of those over at the 4bt forum. I'm a cummins conversion junky as well.

Sadly, I do not do work for others at this time. I am in my 70s and suddenly my time is more important to me than it used to be. I find that I am not longer able to deal with persons looking for a deal and or want something for free.
It is time for someone else to take up the challenge.

 

[ADSR]

Sadly, I do not do work for others at this time. I am in my 70s and suddenly my time is more important to me than it used to be. I find that I am not longer able to deal with persons looking for a deal and or want something for free.
It is time for someone else to take up the challenge.

You got a good 25 years left, my friend. Keep going and enjoy life!! Thanks for posting this project.

 

[2nr]

Very nifty idea, may I borrow it for my next Cummins conversion?

Sent from my Moto G (4) using Tapatalk

 

[isb cornbinder]

Help yourself.

 

[isb cornbinder]

Well done, Sir. I bet you could sell a tone of those over at the 4bt forum. I'm a Cummins conversion junky as well.

Sorry for a late reply. If every person were as positive as you, their suggestions would be welcomed. I am eyeing the crate engine 2.8 liter. I am considering installing a 2.8 in my 1940 Ford.

 

[isb cornbinder]

Sorry for a late reply. If every person were as positive as you, their suggestions would be welcomed. I am eyeing the crate engine 2.8 liter. I am considering installing a 2.8 in my 1940 Ford.

I paid much more than the real value of this tachometer. I wanted this and few are available, so the collision of two realities made the price what I paid.
A local print and sticker shop is going to reproduce the colorful face of this tachometer so I can have extras to convert the extra SW tachometers I have to the old look.
I must open the tachometer and remove the face for scanning. I will put it in my smaller lathe and try to roll the edge back. I have a round tool in mind.

 

[NakeDiesel]

Here's my current tack pickup on my mud race truck. I had 2 additional notches machined into the harmonic balancer and epoxied 4 magnets into the notches so that the pickup would read 4 triggers for rev and I use a 4 cylinder tach.



my old design that use the 4 bolt holes to trigger on

 

[isb cornbinder]

Very nifty idea, may I borrow it for my next Cummins conversion?

Sent from my Moto G (4) using Tapatalk

If you copy what I did, I would feel honored. Make sure you post pictures so others might learn something from your design.
You posted, "my next Cummins conversion." I bought a new 24 valve at an insurance auction. The RAM was the victum of a test drive that did not return.
I have been giving too much thought to doing a "P" pump conversion. What say you?
When I get back out to the shop, I want to install a Killer Dowel Pin lock on my 4bta. I have a remote filter relocate kit in line for some attention. https://pacbrake.com/hp10588-remote...so_3b8WbmCMfq-lcHK9JM2KaHMqyWyqfpGyNdfRESo4X7
https://www.amazon.ca/s?k=killer+dowel+pin+kit+cummins&crid=2XHO05VLB1LSS&sprefix=killer+dowel+pin,aps,134&ref=nb_sb_ss_ts-doa-p_1_16