pkhammer Posted October 22, 2022 Share Posted October 22, 2022 I recently bought a non-running '29 Model A Ford sedan. I was told it wouldn't start because of a couple of stuck valves. I inspected the valves and they seemed fine so I connected the battery and tried to turn it over. All I got was the "whirrrrr" of the started bendix spinning and not engaging in the flywheel. Looking a bit deeper I see the car has an alternator so is obviously converted to 12 volt. Back to the battery I see a 6 volt battery installed with positive ground. I'm not the sharpest mechanic but since it has been converted to 12 volt shouldn't it need a 12 volt battery? Shouldn't the negative be grounded since converted and not the positive? Link to comment Share on other sites More sharing options...
PONTIAC1953 Posted October 22, 2022 Share Posted October 22, 2022 they make a six volt alternator, so don't assume that it's a twelve volt one. 5 Link to comment Share on other sites More sharing options...
Pete O Posted October 22, 2022 Share Posted October 22, 2022 They also make a positive ground 6v alternator for the Model A, so don't switch polarity until you know what you have. Is there a label or tag on the alternator? The failure of the bendix to engage could be that it's just clogged up with crud and/or rust from sitting. Take the starter out, it's not hard to do. Disconnect the battery, remove the battery cable from the starter, unscrew the starter switch rod from the switch, three bolts hold the starter to the flywheel housing and bingo. Look for a broken bendix spring and make sure both bolts holding the spring are intact and the tabs on the lockwashers is bent up to hold the bolts in place. Spray the whole bendix assembly with a penetrating oil to free it up so the gear will slide freely on the shaft. 4 Link to comment Share on other sites More sharing options...
F&J Posted October 22, 2022 Share Posted October 22, 2022 50 minutes ago, pkhammer said: All I got was the "whirrrrr" of the started bendix spinning and not engaging in the flywheel. I typed too slow, Pete gave the info: Run the web search with the alternator numbers/brand name to know if it's 12v. Definitely a broken Bendix spring unless the car sat forever in a wet climate and the Bendix rusted up to the shaft. I had an original/old Model Bendix spring break because the 12 volts makes a sudden very violent initial movement compared to 6 volts. I have read of many A's breaking the old spring on 12 volts. I don't know of a new spring would also break after a while on 12v, as we don't know if repro springs have better steel or worse. Link to comment Share on other sites More sharing options...
pkhammer Posted October 22, 2022 Author Share Posted October 22, 2022 After taking a closer look it is a Delco-Remy alternator and among the hard to read letters/numbers stamped in the case you can make out "12VNEG". Here are a few pics. Link to comment Share on other sites More sharing options...
pkhammer Posted October 23, 2022 Author Share Posted October 23, 2022 So the mystery deepens. Some have pointed out that the alternator could've have a 6 volt conversion and although it says "12VNEG" on the case it could still be 6 volt. I had a "duh!" moment and went and checked the coil. The coil is 6 Volt. I've never done a 6 to 12 volt conversion nor have I ever replaced a generator with and alternator so to say I'm baffled is an understatement. I'll remove the starter next and check the bendix and spring. 1 Link to comment Share on other sites More sharing options...
trimacar Posted October 23, 2022 Share Posted October 23, 2022 (edited) Personally I’d start over, put a stock Model A generator and starter on it (you mentioned to me that the starter was not stock?) . All the “improvements” are just confusing things. Other alternative is a pull start, hook up a tow strap and see if it starts! I know you’re having fun…. Edited October 23, 2022 by trimacar (see edit history) 1 1 Link to comment Share on other sites More sharing options...
pkhammer Posted October 23, 2022 Author Share Posted October 23, 2022 I was wrong about the starter, it is stock model A with the fuse added. I have a rebuilt model A generator here so it is tempting to return it to stock. However on the other hand it was supposedly running well a few months ago so first I think I need to pull the starter and see why the bendix is not engaging the flywheel and go from there. 1 Link to comment Share on other sites More sharing options...
Restorer32 Posted October 23, 2022 Share Posted October 23, 2022 If there is no compression it can almost sound like the starter is not engaging when it actually is. Link to comment Share on other sites More sharing options...
pkhammer Posted October 23, 2022 Author Share Posted October 23, 2022 I checked and the engine is definitely not turning, just the starter motor spinning. Link to comment Share on other sites More sharing options...
Oldtech Posted October 24, 2022 Share Posted October 24, 2022 Maybe check the light bulb voltage and see if someone did an actual conversion or just stuck an alternator on it. Anything is possible. But yes, time to pull the starter and investigate. Link to comment Share on other sites More sharing options...
TerryB Posted October 24, 2022 Share Posted October 24, 2022 (edited) Did you try turning the engine over with the hand crank to see if it has compression? Edited October 24, 2022 by TerryB (see edit history) Link to comment Share on other sites More sharing options...
pkhammer Posted October 24, 2022 Author Share Posted October 24, 2022 Unfortunately no, I don't have the hand crank. Link to comment Share on other sites More sharing options...
trimacar Posted October 24, 2022 Share Posted October 24, 2022 You need a push rope in front of the Model A…. 1 2 Link to comment Share on other sites More sharing options...
Larry Schramm Posted November 4, 2022 Share Posted November 4, 2022 I would take the alternator off the car and take it to a repair shop and have them check it for either 6 or 12 volt output. It is possible that someone had it changed over to 6 volts. Just a way to confirm what the output of the alternator is. 3 Link to comment Share on other sites More sharing options...
Tonz Posted November 6, 2022 Share Posted November 6, 2022 Like me, all you guys should have a friendly neighbourhood auto eleccy who can spin up your genn/alt and tell you on the spot if it's 6/12v or neg/pos earth. I was fortunate that in my town was an elderly (should be retired) auto electrician who was happy to test all my gear and educate me to a basic understanding of my 26 Chrysler. He made me up a set of 6v cables and bench tested my battery and Genny for 30 minutes. My old car spins up and starts like a new one. He also mentioned that the main difference between 6/12 v starters was the mass of the centrifugal throw out. Which can be lightened for 12v use, or it will eventually self destruct. These old school guys are scarce now and of great value if you know one. 1 Link to comment Share on other sites More sharing options...
Doctor's Pontiac Posted November 7, 2022 Share Posted November 7, 2022 My 33 model B had same problem. I finished restoring car back in 2016 and had used an aftermarket bendix, some Chinese part because car is hardly driven, may be every 2 months, and was expected to be sufficient for such low intensity use. But junk is junk and it lasted only 4+ years and some of its splines wore out and produced same sound you described and was not engaging. Put an NOS bendix a year ago that solved problem. I do have a 6 volt positive ground alternator. I gave up on trying the generator after several unsuccessful rebuilds. I know, if I just find the right electrician…… 1 Link to comment Share on other sites More sharing options...
pkhammer Posted November 7, 2022 Author Share Posted November 7, 2022 Haven't had a lot of time to mess with it but I do have the starter engaging the engine now. The alternator is still a mystery 🤔. Engine spins over freely like no compression which was baffling at first. Removed valve cover and no valves were stuck in the up position. Hmmm... Turns out the valves aren't stuck but they are sticky. The intake valves when opened, very slowly return to the closed position. When spinning the engine over the valves don't have sufficient time to return to closed so basically just stay open. Freeing them up is next on the agenda......................... Link to comment Share on other sites More sharing options...
Oldtech Posted November 8, 2022 Share Posted November 8, 2022 You need to find out what that alternator actually is. It has apparently been modded because it only has one wire, so at the least it APPEARS to have a self exciting regulator installed. If you are not alternator friendly best to take it to a shop where they can test it. could be redone for 6 volt, neg or pos ground ... or not. 2 Link to comment Share on other sites More sharing options...
Bloo Posted November 8, 2022 Share Posted November 8, 2022 Have a closer look at this picture.... It is clearly modified. The output post is grounded to the case and a second post has been added at the other end of the diode stack. It is almost certainly positive ground. Occams razor would suggest that it is also 6 volts. 5 Link to comment Share on other sites More sharing options...
Larry Schramm Posted November 8, 2022 Share Posted November 8, 2022 It is definitely a GM alternator. I would not even try to guess what you have. If you look at the top of the alternator you will see two terminals that are usually used for the voltage regulator and there is nothing connected to them. You need to take the unit to a reputable shop and have them see what you have. Might just be cheaper to buy a new unit that is correct to what you want on your car. 2 Link to comment Share on other sites More sharing options...
Oldtech Posted November 8, 2022 Share Posted November 8, 2022 I'm thinking its 6 volt pos ground. but you need to find out. 1 Link to comment Share on other sites More sharing options...
pkhammer Posted November 8, 2022 Author Share Posted November 8, 2022 Thank you all for the input. The car had been running on a 6 volt positive ground battery and the coil is 6v so I am pretty convinced that someone set it up intentionally as a 6 volt positive ground system. I probably should get it tested to be certain however and not make any assumptions. Link to comment Share on other sites More sharing options...
MCHinson Posted November 8, 2022 Share Posted November 8, 2022 In years past, it was not that unusual to see similar alternators converted to 6 volt positive ground and used on Model A Fords. I would fix the starter drive, start it up and see what you have. I expect you will find the alternator to be charging your 6 volt battery just like it did before the starter drive failed. 1 Link to comment Share on other sites More sharing options...
pkhammer Posted November 8, 2022 Author Share Posted November 8, 2022 Starter is fixed. Now I need to free up some sticky valves before attempting to start it. Link to comment Share on other sites More sharing options...
pkhammer Posted December 2, 2022 Author Share Posted December 2, 2022 Alternator is 6V positive ground so hopefully no more electrical issues. Been spraying (lower) valve stems with penetrating oil with little success. Turn engine over and intake valves would open but a couple of them would very slowly return to closed position. Took the intake/exhaust manifold off so I could get to upper valve stems. Sprayed with carb cleaner, then turn engine over, stick finger in port and wipe crud off stem, then repeat. After several rounds of that sprayed them with more penetrating oil and finally, valves are moving freely!! Yay!! Engine now seems to have compression!! Now, need to change oil, overhaul carb, re-install manifolds, valve cover and carb and see if it'll run!! @Matt Harwoodrecently stated in a thread about his Chevy tow truck that he thought that everything he purchased ended up needing WAY more work than initially thought. I think we've all been there. I know I have!! It seems ever car I purchase needs about 5X the work I think it does! Link to comment Share on other sites More sharing options...
Akstraw Posted December 5, 2022 Share Posted December 5, 2022 (edited) Good luck! I think bringing a Model A back to life is exciting. They are unusually straightforward to work on, once you get to know them. Lots of resources available, too. If I lived next door, I would be helping you every week. The guys above are giving good advice. Keep plugging away; you’ll figure it out. Let us know what you learn. Edited December 5, 2022 by Akstraw Added info (see edit history) Link to comment Share on other sites More sharing options...
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