First Gen Cummins Tachometer Install 

Kelly, thanks for the feedback! I printed this using PETG (higher temp resistance and strength than PLA... required for hot summer days), and I'm confident the dash would shake apart before my tach housing broke or fell off. It has been going strong for a year now and I haven't had any issues whatsoever (robust design, 3D printer setup / settings, material and inherent vibration damping of the plastic all play a role I think). As for the switch panel, that was also something I custom designed and 3D printed. Overall I've been really happy with it as well. All the switches run a relay panel I made and installed in the engine compartment (relay panel can be seen at 3:19 in my other Cummins YT video here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-oFdwheRW4-I.html).

@@hevvyevvy A question, again, about your switch panel; I can't get a good look at how you mounted it. I'm currently designing one, similar to yours, but in addressing the mounting, I got curious how you went about it, and how well it has held up since (assumed fastened with screws of some sort). I will have a few more components in my panel than yours; I'm going to be adding air bags in the rear, and the kit I have picked out comes with a roughly 2" gauge and air switch, that I'd like to have fit into my panel, as well. So mine will have a little more weight when I'm bouncing around. (I use my truck like a UTV; it's a farm truck as well as a trail rig) If you were to do it again, what would you do different? Any tips for backlighting the switch labels? Any other tips, tricks, considerations you could pass on, would be appreciated as well. I also liked how you did your fuse/relay panel! It looks simple enough, I will probably do something very similar, for all my accessories! Thanks, again!

@@Kelly-zi9vg I'm going to be making another switch panel with better backlighting in the future... The label backlighting system I designed is perfect for night driving, but isn't very visible in the daylight... I'll share the updates in another video, hopefully soon. I'd like to have the switch labels be a little more "modular" i.e. easier to change the labels around if I want to change the switch function. I fastened this switch panel to the dash using heavy duty 3M molding tape... Held up brilliantly over the 1.5 years it's been installed. The key is to ensure you have enough surface area for the tape to adhere (greater load/weight = greater surface area). I didn't want to drill any more holes in my dash than absolutely necessary! If I were to design the switch panel again, I would have added more void space and made the panel a bit bigger to make assembly/install easier. I've installed a few relay panels similar to this one. It's no frills, but gets the job done pretty reliably.

I would definitely make more if there's interest. Tach info is also in description, it's a Seastar 68358P (from amazon.ca), other Seastar 3" tachs should work as well (68398P, etc)

Hi Bogdan, my understanding is that the "W" signal from the tach produces an AC voltage where the frequency varies with engine speed; since a rheostat (potentiometer) wouldn't change the frequency, I'm not sure it would have the adjustment effect you're hoping for... Give it a try and let us know if it works though!

Jim, the tachometer is listed in the video description. Sierra Designs Seastar 68358P (purchased amazon.ca). Where I live, we have snow / salt / sand 7-8 months of the year, it's going to be tough to avoid! As for cutting off water pump blades? I thought that was generally reserved for racing engines? I wouldn't want to have less cooling capacity than factory if I was daily driving or towing with the truck. I have the 3200 RPM governor spring and have been very happy with it.

Yep, I'm willing to print additional units to sell. Right now I'm updating the housing design with a sun visor to keep glare off as well!

That's correct, the 91.5+ have a dedicated tachometer connector, which gets its signal from the ECU (via the crank position sensor). This is more reliable and accurate than the alternator-based tach which I have used; however, the Isspro and factory tachometers which are compatible are very expensive. I was looking for a bit more budget-friendly solution. I thought about trying to do something with the factory tach pulse signal using Arduino, but never got around to it once I decided on the marine tach route.

@@hevvyevvy Well mine's a 1990 D250 - No computer. So the jury's still out.

I just checked, no heavy yellow wire on the tachometer connector. I'm 95% sure your 1990 doesn't have the connector, do you have a crank position sensor at the harmonic balancer? If not, no factory tach signal.

@@hevvyevvy I have no such things, My Child. I just noticed a weird rectangular connector inside my dash. I just cut it out of there. I love the simplicity of my 1990 1st Gen. For instance, I did the whole brake system upgrade: A disc brake kit for the rear end, and after that, the ABS delete (It was inoperative, anyway, sending all the braking to the front end). Best breaking system you can have on these trucks.

Hi Jake, I haven't printed any for sale yet but I'd be willing to. Let me know if you're interested and we can connect.

@@hevvyevvy I would buy one if you printed one

The only wire I didn't explain how to hook up was the tachometer "w" signal wire, because I did that first before deciding to film anything. Plenty of good videos on YT how to tap into that signal though! My mount was really the thing I was trying to highlight, but I did get into the tach setup later on in the video. Any questions feel free to fire away.

Yeah, you’re exactly right. The actual mounting of the tach is a minor detail that is relevant only to the particular project. Like everyone of us has access to a 3-D printer for the love of God!