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Delco 752 8C3, Intro to the forum

ff4312

New member
Hi all. I'm a newcomer to antique engines. Been admiring hit 'n miss engines for years. Work on old cars and tube radios for fun currently. Saw a delco light plant about a year ago and became intrigued. Anyways, I just bought a model 752 8C3. Needs a full restoration. As I wait for it to arrive, what are some tips and things to look for? I'm pretty sure that the "C" designation means combination, and is therefore one of the self starting models. Is there a way to test the windings in the starter/generator?
What oil should be used in the sump? etc.
Anyways, Hello!
 

tbird255

New member
Following!
Ditto the OP, New to the Forum and new to delco-light with a 752 acquisition (stuck, but otherwise mechanically intact).
Looking for all the same answers. At least we can commiserate. ... so far, the only thing I cant get remove - the spark-plug. I actually unthreaded the core without issue, but cant get the base out of the head. Oil runs past the piston OK, so I hope that I can remove the piston with grease (once I get the plug out).
 

ff4312

New member
Well ok then! I didn’t post to a bunch of crickets after all. Lol.
I’m still waiting for mine to get here but I do know it turns over. Might want to try a ton of pb blaster. I’ve had good luck with that.
 

tbird255

New member
Yeah, lots of PB already working on it. I think I got the plug to turn like.... a 1/16th of a turn (just enough you can tell it moved.... but not enough for it to be loose yet). I may fill the cylinder with waste oil again and heat the plug to try and draw oil up from the base.... since blaster may not be getting down past the shoulder seat of the plug.

Maybe we can commiserate on our projects. I have the wiring diagram intact for mine, but the carb/mixer has been removed and the wires cut - so I have no idea how the air solenoids and the preheater would get wired (cause that info is NOT on the wiring diagram....that I can see)

I wouldn't mind buying a manual, but id like to see what I'm getting first. There are some service info floating around, but for some reason, few like to scan and share.
 

ff4312

New member
So mine came home today. I too have the diagram inside the panel but it is not far away from giving up the ghost. I may carefully remove it and scan it for reproduction purposes and save the original in a plastic sleeve. Anyways it does show on mine that the heater is fed from junction #3 and grounding to chassis ground. The air solenoids are still connected on mine. Not sure if its correct but its been on this way a long time. Inner solenoid is junction 20 and 14, outer is 20 and 24.
Biggest issue I can see is significant rust in the exhaust port and a stuck valve. Obviously going to have to take this all the way apart and see what I've got. :shrug:

I too am interested in a manual but kinda want to know what I'm getting.

Also my serial number is 321064, be interesting to know its production range.

Keep in touch!
 

Attachments

tbird255

New member
Nice.
Regarding scanning the schematic - try just using an app on your phone/tablet. from my experience, they clean more and process away "noise" better than many computer scanners. I've scanned old tractor manuals, and the greasy fingerprints just magically disappear.

Hope your valve frees up well. Once I get the sparkplug out, and the piston out, then I have to get both the exhaust and intake valves out. In my experience with tractors, at least they can be driven out relatively easily (with patience), then a rifle bore brush to clean the guide and hope the seats clean up without too much work.

How do your fuel pump and points look?
 

Grape

Subscriber
Do a search in the forums for Delco light and a lot of info will show up. You will quickly see who the forum experts are by the replies. Then try contacting them direct by private message.
I've got an old Kohler that I want to get back to work on soon but don't have much info on delco's myself.
Good luck :)
 

ff4312

New member
Thanks Grape.

Mine is starting to look like a fairly crusty critter. The cam lobs have rust that's past just being surface, the followers may or may not polish out. I think the crank is ok but the connecting rod big end journal is fairly scored. Exhaust valve still stuck shut. Not sure what to do at this point. I haven't even gotten into checking windings or the electrical side yet.:uhoh:
 

tbird255

New member
Re pitting on the cams - when you say pitting, are you talking isolated pits, or does the whole cam look like the surface of the moon? From an engineering standpoint, minor pitting is not much of an issue. as long as the majority of the bearing surface is clean, a pit will just be a place to hold oil. Just like you rod - if your crank is good, your rod can be saved by most any competent machinist. grind/mill .010... or more off the mating surface of the rod, and re-bore the rod to match the crank.
 

ff4312

New member
It’s pretty bad. Not a simple polish job. I’ll send a photo when I get home. Im wondering if it could be welded and reground.
 
Yes. Delco engines are pretty basic 4 cycle one lungers that respond to regular engine rebuilt techniques. Since they're also slow speed, most repairs are nowhere near what a car engine would need. I've seen both Delco's and hit/miss engines in far worse shape restored to beautiful runners.

The crankshaft (assuming scored) will probably need to be pulled and have metal sprayed on (or welded), then ground to a standard size...a technique used in engine rebuild shops these days. Note that Delco used roller and ball main bearings which are difficult to find these days.............HOWEVER...........due to their modest speed the bearings are almost always reusable, unless horribly pitted.

The cam should respond to the same treatment....ask the engine shop. You'll need the rod's big end re-babbitted. Bore can be honed to improve it and new rings are available from a vendor here on the site. Valves take the normal treatment, and if the exhaust valve is fried there are various size valves available at any engine rebuild shop. I'm running a couple of model T Ford valves (with oversize stems) in my 850. Cost about $16 for both of them. That horrible looking gear might surprise you by running just fine in the oil bath. If not, put out a call for help and someone with a decent gear will probably answer.

Most of the time the generators have insulation problems due to mice or being oil soaked. Okay, so degrease the wiring and use heat shrink on it. Field coil insulation a little shaky? Trim off any loose stuff and spray with high temp red lacquer, as used on motor windings. Reassemble everything following the schematics in a reproduction manual available from FDChief on the website.

The biggest problem is to learn how to take your time. Enjoy the rebuild! Go easy, one thing at a time and suddenly.........it's running!:) By the way, see my post on 32 volt LED bulbs.
 
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ff4312

New member
George, that’s the most uplifting thing I’ve read in days. Thanks for that. Any idea what the machine work should cost? I need a frame of reference so I don’t get taken for a ride. Probably have to do this in stages I would imagine. Need someone that can weld the rocker pedestal mount and fuel pump housing back together as well. Can’t imagine that would be too bad didn’t wise though.
 
The only reference I have personally is for the welding and machining of a model T Ford crankshaft I had done about two years ago......around $150 if I recall. If you think about it though that's for a four cylinder crank, so four mains and four rod bearings.....not to mention the set up time, etc. I think if you ask at some auto engine rebuild shops, they can point you to someone that can help. You'll find most repair shops slightly sympathetic to restorers, especially if they take an interest in what your doing. Most of them have never heard of a 32 volt electrical system, so a quick historical presentation can spark their interest.

When you say rocker arm pedestal, is that part of the head casting itself? If so, the entire head needs to be squeaky clean to prevent old oil from migrating to the welded area. Do that part yourself and save the welder the chore, which saves money. There are welders on the antique tractor websites that specialize in exhaust manifold welding. If they can weld a manifold and get good results, a head should be a piece of cake!

Probably the best advice I can give is to do the restoration one step at a time, as money permits. Sure, it'll take longer but each bit will be properly repaired and can be set to the back of the bench to await reassembly. Hey, I worked on my Delco 850 for about six months......at my leisure........and was rewarded with a unit that actually lights my shop!

Above all, keep everyone here posted on your progress.
 

ff4312

New member
Update with some good news. The valves are out. A good soaking and a few taps to get the exhaust out. With some of the crude cleaned out I think the cylinder along with the intake valve can be put back to service after some work. Ive put out some inquiries and am waiting to hear back from the machine shops whether they want to touch the cam or not. Flywheel came off as well. Currently soaking the front cover with some penetrating oil to get the crank out. Long way to go but I’m feeling a bit better about this. I’ll keep posting and asking questions as I go. Thank you all.
 

ff4312

New member
Before I break something, what is the order of disassembly to get the crank out?. Does the generator end need to be disassembled? Guess it's time to get the manual. Flywheel and front cover are off currently.
Thanks.
 
I didn't have to remove the generator from my 850 crankshaft (thank goodness!), but I looked it over carefully and it appeared to need a special puller constructed. I honestly don't remember why now, but I know I couldn't just "pull 'er off".
 

ff4312

New member
Maybe I just clean her up and polish the crank/rod journals and call it a day. I've seen engines work with much worse scoring then this. It's not like I'm putting this back to everyday service and its low rpm at that. Probably just a working display that has some usefulness if a hurricane blows through (I'm in Florida). Apparently the machine shops in my area don't answer emails or business is so good that customer service is an afterthought. I'll have to call on a lunch break and see if I can find someone up to welding and regrinding the camshaft. That seems to be the biggest hurdle at the moment. Thanks for the input guys. This forum is fairly quiet compared to the antiqueradios.com forums or theSamba. Guess there is less interest unfortunately.
Its funny, I'm technically a millennial and when I go to work and show others my projects it blows their minds. They can't believe this stuff can still work. I tell them, "Go try this with a Tesla in 80 some odd years". They usually have no comment. :D
 

slip knot

Subscriber
I don't have much input from the Delco side but the engine work is standard fare for an automotive machine shop. Maybe you need to refine your search for a machine shop. Around here we have several big machine shops that wont even touch a job for less than a grand$$ then we have a few little guys that will rebuild a cylinder head or bore a block for a few hundred. may try looking for a smaller auto type machinist.

Good luck with your project. We all have the things that intrigue us. Sometimes it easy to get answers sometimes not. To me that's some of the fun in repairing the old stuff.:salute:
 
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