u/FullSizeChevy_com

This one is from before the Ferguson merger - a 1952 Massey-Harris 30 - but it is Massey family so I figured it belongs here.

I finished converting it from the original 6V positive ground system to 12V negative ground. The alternator is a GM Delco 10SI 63A from a Chevy Squarebody, single wire and self-exciting, so the electrical side is straightforward once it is mounted.

Mounting was the actual project. Fabricating the bracket and getting everything aligned was by far the most work, and the alternator had to move about 3/4" forward toward the crank pulley before the belt ran right.

Charging results:

• Stock generator pulley, 600 engine RPM: just over 13V. It charges, but I was not comfortable leaving it there.
• Stock generator pulley, idle raised to roughly 650 RPM: 14.4V. That is where it sits now.
• A 2" pulley with a 17mm bore on the 10SI should hit 14.4V at 600 RPM by my calculations, if you can find one.

I chose a voltmeter over the period-correct 60A ammeter that is available. I would rather have the information about battery and wiring condition than the matching look, though I do still want to find a voltmeter that suits the tractor better than the Amazon one in there now. The water temperature and oil pressure gauges got replaced at the same time.

If I did another one I would use the internally resisted ABC6158 coil and drop the external ballast resistor. The 55,000V hot coil has been great regardless - it barely cranks before it lights.

Full writeup with the wiring diagram and the pulley math:

https://forum.fullsizechevy.com/t/1952-massey-harris-30-6v-to-12v-negative-ground-conversion-delco-10si-wiring-diagram-pulley-math/632

This is my own tractor and my own conversion work.

Just wrapped up a 6V positive ground to 12V negative ground conversion on my 1952 Massey-Harris 30. Posting the details because when I started this I had a hard time finding real numbers on the charging side of it, and most of what I learned applies to any old tractor you would want to convert.

The alternator is a GM Delco 10SI 63A pulled from a Chevy Squarebody. It is a single-wire, self-exciting unit, which is what makes this swap worth doing on an old machine - there is no external regulator and almost nothing to wire.

The hard part is mechanical, not electrical. Fabricating the bracket and getting the alternator aligned took the bulk of the project. The alternator ended up needing to sit about 3/4" forward of where the generator was, toward the crank pulley, to get the belt running true.

On charging speed, which is where I would have wanted someone else's numbers:

• Stock generator pulley at 600 engine RPM gave me just over 13V. Charging, but slowly.
• Stock pulley with the idle raised to about 650 RPM gets me to 14.4V, which is what I was after. I wanted the battery gaining while the tractor idles, not just while it is working.
• A 2" pulley with a 17mm bore on the 10SI should get you 14.4V at 600 RPM without raising the idle at all. I could not source one, so I went the idle-speed route.

I fitted a voltmeter instead of an ammeter. A 60A ammeter is available if you care about keeping the dash period correct, but the voltmeter gives me a much better read on battery and wiring condition. I also replaced the water temperature and oil pressure gauges during the job.

One lesson: I used an external ballast resistor with the coil. There is an internally resisted coil (ABC6158) that would have made the ballast unnecessary. If you are doing this, buy that one. The 55,000V hot coil itself has been excellent - it fires almost immediately on crank.

I wrote the whole thing up with the wiring diagram and the pulley math here:

https://forum.fullsizechevy.com/t/1952-massey-harris-30-6v-to-12v-negative-ground-conversion-delco-10si-wiring-diagram-pulley-math/632

My tractor, my conversion, my writeup. Ask away if anything is unclear.

Oil change, rust repair, a wash, parts that showed up, parts that showed up wrong, or a bolt you rounded off and walked away from. It all counts.

We keep a mega thread going for this over at FullSizeChevy - OBS through T1XX, every generation welcome. Post what you got done:

https://forum.fullsizechevy.com/t/what-did-you-do-to-your-truck-today/590

Did a catch can install on my K2XX Sierra (5.3 EcoTec3) this week, replacing the factory PCV routing with the K&N 81-0805. Wrote up the whole thing — tools, the tricky lower PCV line, why the can mounts facing down, and hose routing.

The part I actually wanted to see: pulled the can after ~60 miles of normal driving and there was already oil sitting in the bottom. Not a magic fix, but it's clearly intercepting vapor before it heads back to the intake.

Full write-up with parts list: https://forum.fullsizechevy.com/t/k2xx-catch-can-install-2014-2018-silverado-sierra-k-n-81-0805/630

Full video walkthrough if you'd rather watch: https://www.youtube.com/watch?v=aWc0ddX7rMA

Anyone else running one on a K2XX 5.3? Curious how much you're catching over a longer interval.

If your battery dead overnight again? Or your truck cranks fine Saturday and is dead by Thursday after sitting? That's not "just a bad battery" — it's almost always a parasitic draw. I'll be honest, these suck to troubleshoot, and batteries are getting expensive to replace.

On GMT400, GMT800, GMT900, and K2XX trucks (Silverado, Sierra, Tahoe, Suburban, Yukon, Avalanche), the usual suspects are a module (cough Onstar) that won't go to sleep, a bad alternator diode, an aftermarket stereo or amp, a faulty remote starter, a stuck interior light switch, trailer wiring, or just bad wiring from a past install.

We put together a full video and written guide on how to test it yourself with a multimeter or DC clamp meter, how to let the truck go to sleep before testing, and how to pull fuses one at a time to chase down the culprit. It can be a pain in the butt to troubleshoot. The best bet is to do it using a 100A DC Clamp on meter. If you don't have one, maybe you can borrow one from a buddy (or call your electrician friend and ask nicely to borrow one for a case of beer). With a bit of time and a multimeter, you can usually find the parasitic draw yourself and avoid handing over your hard-earned money to a repair shop.

There's a bit to it, and I will be honest it sucks to troubleshoot as it can literally be anything ( a wire, a module, a light, etc). My GMT400 had faulty stereo wiring from the previous owner. My GMT800 had a faulty TCM that would kill it within 4 days. My GMT900 had a failed Bose amp that would kill it within a week. The goal is to find and isolate the parasitic draw and then correct and repair the circuit.

I also included 2 separate temporary fixes that I've used in the past to always ensure your truck will always start. Not permanent fixes; but they can get you by until you get the parasitic draw fixed. I understand how life can be busy, and honestly these fixes were helpful for me until I was able to fix the draws on my rigs.

Anyways, the full video is here: https://youtu.be/K1Tu2R1PqrM

The Full how-to is here: https://fullsizechevy.com/how-to-find-a-parasitic-battery-draw-on-gmt400-gmt800-gmt900-k2xx-trucks/

If you are stuck on your specific truck you are also welcome to post it on the forum and we'll help you dig in: https://forum.fullsizechevy.com/t/help-diagnose-my-parasitic-battery-draw/593/2

I'm also interested in hearing what other parasitic draws you guys have worked through. I would like to add them to the website for the master guide on items to troubleshoot.

Thanks and good luck troubleshooting your parasitic draw!

The 2500 Avalanche Build Thread is live.

I finally started documenting the 8.1L 2500 Avalanche build.

This one is getting used the way GM intended — towing, hauling, cruising, and burning fuel in a big-block GMT800.

You can check the thread out here:

https://forum.fullsizechevy.com/t/2002-avalanche-2500-8-1l/591

Got a 2500 Avalanche, 8.1L truck, or GMT800 build? Drop it in the forum. Let’s get some real build threads going.