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#68008 10/30/2006 9:58 PM | Joined: Oct 2006 Posts: 63 Shop Shark | | Shop Shark Joined: Oct 2006 Posts: 63 | It's alive!
I bought a new 6 volt battery but it just wouldn't crank the engine like the 12 volt I was using to "limber up" the engine. You guys said to disconnect everything else while using the 12 volt, which I did. I decided to skip the ammeter-ignition switch circuit and eliminate all the other peripherals powered off them. So, I connected the coil right to the starter terminal where the battery connects. Thus: battery-starter coil-distributer-plugs-ground. Am I wrong in guessing that none of these might be damaged by the 12 volt? Not sure about the distributer points --- any thoughts? At any rate, I took the risk and she fired right up and ran on starter fluid! Started it 5 or 6 times, ran 5 seconds on starter fluid, then battery ran down. SO, I will convert this system to 12 volt, which I haven't researched yet. But should I avoid temporarily starting it this way? --- I will rebuild carb tonight and would like to get it running smoothly on gas tomorrow. | | |
#68009 10/30/2006 10:38 PM | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | John,
Congratulations....If you are going to go with 12 volts eventually, you could buy a internally resisted 12 volt coil now, stick it on and be done with the ignition end of the swap.
If you have the proper sized battery cables, clean connections and a fully charged battery, the truck should start the same on 6 volts as it does on 12 volts.
If you go the 12 volt route, with the coil done, your only other concerns would be the charging system and lamps..maybe the heater motor and fuel gauge.
Lots of these trucks are still 6 volt and work great.
Stuart | | |
#68010 10/30/2006 10:47 PM | Joined: Oct 2006 Posts: 63 Shop Shark | | Shop Shark Joined: Oct 2006 Posts: 63 | Stuart,
I wouldn't mind sticking with the 6 volt system, but that 6 volt battery can barely turn the engine. It's rated 625 cold crank --- greater than the 12 volt! I wonder if it's a bad battery? I charged it up completely. The 12 volt gets drained after 6 or 7 cranks of 10 seconds each. That seems a large power draw, doesn't it? Maybe the engine is so tight it's hard for the batteries to turn it. It did start though. | | |
#68011 10/30/2006 11:15 PM | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | John, It's a tough call. There are a multitude of tests to check out starter current draw, and voltage drop across connections etc. I am sure you just want the thing to run. If you bought the 12 volt coil, rebuilt the carburetor and got it running, you could get the cobwebs worked out of it, then figure out which way to go. Seven 10 second cranks is some pretty hefty cranking. A engine is usually only tight after an initial rebuild. Hard cranking with a KNOW good battery is usually poor connections, undersize cables or a worn out starter. If you do all your carburetor stuff, put in the 12 volt coil (cheap) and get it running nicely, then you could address the 6 volt hard start situation. If you do it this way, you will be running off the battery so extended road trips will be out!  Maybe someone else has a different take on this deal. Stuart | | |
#68012 10/31/2006 1:11 AM | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | A 6v system will turn a 6v starter just fine as long as you have the following:
1. A good battery (Optima makes the strongest 6 battery)
2. A good 6v starter
3. A good spark (a 6v Perronix system is great for this but not necessary).
Most important:
1. A proper gauge positive battery lead (from the battery to the starter). Most battery leads from the last 30-40 years are 4 gauge (fine for 12v). The minimum gauge you need is 2 gauge but 00 (2/0) is the best for a 6v system.
2. A proper gauge negative battery lead (from the battery to the starter). Most battery leads from the last 30-40 years are 4 gauge (fine for 12v). The minimum gauge you need is 2 gauge but 00 (2/0) is the best for a 6v system. I have not been able to find a braided ground lead that is better than 4 gauge (12v) and now use covered 00 (2/00) leads for all my 6v ground leads.
One more thing to consider. Chevrolet trucks ran the ground from the battery to the frame behind the battery. And, then there is a ground lead from the frame to the clutch housing (under the foot-start mechanism). I have taken a lead (sorry about the pun) from 6v GMC trucks and run a long ground-lead cable from the battery to a starter mounting bolt.
Then, also make sure you have good ground straps from the engine to the frame (I do it on both sides of te engine and frame). And, if you have a radio, run a ground strap from the head (behind the distributor) to the firewall.
Or, you could convert to 12v. | | |
#68013 10/31/2006 6:19 AM | Joined: Oct 2006 Posts: 63 Shop Shark | | Shop Shark Joined: Oct 2006 Posts: 63 | Thanks for the tip on strong Optima 6 volt batteries. I'd like to keep the 6 volt system, so for now I'll get a 12 volt coil with internal resistor so I can sweep out the dust. I'll dive into the carb rebuild tomorrow --- the online shop manual's directions seem almost too thorough, more than would seem possible with the parts in my rebuild kit. Any directions to the basic steps online? I have Brownell's restoration book. It was sure nice to hear the '51 leap to life, after who knows how long? The motor vehicle reg. I found in the car was from 1977. BTW, my carb is the mysterious Rochester "C" carb I read about elsewhere on Stovebolt. | | |
#68014 10/31/2006 1:36 PM | Joined: Dec 2005 Posts: 324 Member | | Member Joined: Dec 2005 Posts: 324 | Points and condenser could be damaged by 12V, especially the points.
Make sure your timing is right, that can make it hard to crank a engine.
My 54 and my 39 both crank and start right up using 6 volt system.
"It ain't a truck if you can't hose out the cab."
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#68015 10/31/2006 4:21 PM | Joined: Feb 2000 Posts: 5,228 'Bolter | | 'Bolter Joined: Feb 2000 Posts: 5,228 | You won't have any trouble with the 12 volts on the points for a while, go ahead and start it and get it running. It takes a while to burn them. As far as the rebuild for the carb, don't sweat it, they are a piece of cake to rebuild. Very few moving parts and easy to see where they go. The above post on the battery cable size is correct. Get some 00 size welding cable with new cable ends. Go from battery right to starter on both (+,-), then out to the frame and cab.
First thing now is to get it running and loosened up a bit, get the timming close and set the rpm up to 1500 to 1800 to get the camshaft broke in.
What oil do you have in it? Did you add some break in lube from GM? Any of the 15w40 diesel oils have the right break in stuff all ready in them, just don't use any standard oil. Do a search on oils if you are not sure, plenty has been wrote about them. Short answer is, two years ago the new car makers had the oil companys remove some stuff from the oil which was causing the emissions systems to fail when tested. This was fine for the new engines with roller cams and computor controls, older engines didn't like it come start up time. Diesel oil has not been reformulated yet, so it still has the good additives in it. Joe | | |
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