| 36 Ford | -- 07-13-2010 @ 5:58 PM |
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ok just rebuilt flathead v8 and having a problem cranking the monster, With one 6 volt optima it cranks just enough to barely start it and other times to slow so it won't. This battery cranks out at 800 CA. was thinking about adding another in parrell, so system will still be 6 volt but can draw from another 800 CA battery. when I isolate system and put 12 volts to it, boy it spins like no ones business, starts everytime and really cranks anyone have any experience in this area or go this route.
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| supereal | -- 07-13-2010 @ 9:00 PM |
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Is your slow cranking both hot and cold? If hot only, the engine was likely set up too tight. Modern clearances will cause the problem. Are you sure your starter is actually for six volts? Six and 12 volt starters look the same. An Optima in good condition should turn over any engine with the high CCA power. Be sure the engine is grounded with a strong strap, and your battery cables are actually for 6 volts. Many sold today have thick insulation and 12 volt conductors.
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| 36 Ford | -- 07-14-2010 @ 5:50 AM |
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the problem is hot and cold. it turns but just too slow to start. I put all new cables on the truck as it is a full restoration. The cables are thick with the end sodered in connectors. it is a positive ground system so the positive cable is grounded to a nice bare spot on frame. I did run the negative connection thru a 300 amp disconnect switch. then back to starter. i have two starters, a stock from 36 which still works 6volt and i have a rebuilt 6 volt. my local starter company tells me the starters will work on 6 or 12 volts, the only disclaimer is 12 volts will where it out it if on it too long. thats why i say if i isolate system (not to fry the coil or gen) and I put 12 volt to starter direct it cranks really fast and starts no problem was even thinking about installing another tray with a 12 v battery connected directly to starter and floor switch. and just trickel charge that...and let 6 volt run system and make all those connections together. but again they did this in 36 so i would think i could make it work today. can you recommmend a battery cable size? thanks
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| supereal | -- 07-14-2010 @ 8:42 AM |
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We make up our cables from the stranded type used in welding equipment. Major vendors, such as C&G has them. Look at pages 136 and 137 in their online catalog at www.cgfordparts.com From your information, it appears that you are losing power between the battery and the starter somewhere in the circuit. Place a voltmeter across each leg of the system as you crank the starter. The reading will tell you the loss in that part of the circuit. In a 6 volt system, it doesn't take much resistance to lose most of the power. It is kind of like trying to water your garden with a hose full of holes. Six volt starters will run on 12 volts, but if cranking is prolonged, it is likely you will burn it up. We run a separate ground cable from the grounding point of the strap to one of the starter mounting bolts. A 12 volt cable with eyes on each end will do the job because it isn't rare for the connection between the face of the starter and the clutch housing to be poor, and the extra cable makes up the difference.
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| CharlieStephens | -- 07-14-2010 @ 12:13 PM |
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I would like to repeat supereal's comment since you don't mention that you did it specifically. Did you run a ground strap from the engine to the frame? Be sure all grounds are clean. Be sure there is no paint between the starter and the flywheel housing. Charlie Stephens This message was edited by CharlieStephens on 7-14-10 @ 12:14 PM
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| 36 Ford | -- 07-14-2010 @ 5:55 PM |
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great suggestions lets see if this info helps this is a 1 1/2 ton stake bed truck with flathead v 8 POSITIVE GROUND system. when i got truck it had sat for about 40 plus years and I just had engine rebuilt, as I have been restoring the rest. when i took apart the only "grounding strap" which remeber is the "positve cable off" battery, was connected to frame just behind transmission, on cross memeber. there was nothing going to motor from frame . the other cable "negative off battery" went to starter (which only has one lug and no solenoid). this is how I have it wired now. except between starter and negative battery terminal I put a disconnect switch (300 amp) the speed is the same with and with out the disconnect switch. the positve ground cable I am using is just a battery cable like what would be used on a 12 volt system. do I need to go back to a strap or do i need to add a cable from frame to starter mounting bolt? does this help or change anything.
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| 36 Ford | -- 07-14-2010 @ 7:22 PM |
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ok more information i just went out and looked at everything again. the cables which go from negative side of battery to starter switch (in floor) and then to starter says "Laribee 2 neoprene welding cable 610v" it is think stuff so what do you think. then as I said incorrectly in prior posting, the positve cable goes from positive side of battery to disconnect switch 300 amp then to ground which is frame. that cable is "number 4 welding cable".
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| supereal | -- 07-15-2010 @ 10:05 AM |
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I suspect a high resistance connection in one or more legs of the circuit. Put the leads from a voltmeter across each leg and observe the reading. Each indication is subtracted from the amount actually reaching the starter motor. As your truck has an 8 volt battery, it is likely the problem has existed for a long time, and not properly diagnosed or repaired. 8 Volt batteries are a "crutch", and will shorten the life of electric components of your vehicle.
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| ford38v8 | -- 07-15-2010 @ 10:52 AM |
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36ford, Check the chart at this website: http://www.powerstream.com/Wire_Size.htm 6 volt cars generally use 0 or 00 cables. anything less will not provide enough juice for the starter's requirements and have any left for the coil. Alan
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| CharlieStephens | -- 07-15-2010 @ 12:22 PM |
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Just a few comments on your last couple of posts: Get rid of the 8 volt battery. Check archives for comments on 8 volt batteries and you will find most of the comments are negative. I am not an expert on a ’36 so what I say may not be concourse correct but grounding to the frame cross member should work (my ’37 grounds to the body). You should run a ground strap from the engine to the frame. There should be a small bracket between the end of the starter and one of the oil pan bolts (this acts to both stabilize the starter and is also an additional ground). Why don’t you just put in a solenoid or a correct floor switch? I think your disconnect switch may be undersized for the amperage. Feel it (carefully) to see if it gets hot. The 12 volt size cable you are using for a ground is too small and probably part of the problem. The electrons that go out through one battery post come back to the other and both of the cables need to be designed for 6 volts. Feel it (carefully) to see if it gets hot. I can’t tell from your description of the cables in your last post but my guess is that they are too small. Remember, within reason, you can’t get too many clean grounds or too large of cables on a 6 volt system. Charlie Stephens
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| 36 Ford | -- 07-15-2010 @ 6:03 PM |
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Hey guys not sure how 8 volt battery came into it, I have a V8 flathead motor, I have a 6 volt battery that I am working with all of your suggestions are good so I am going to: 1) up grade cables to "O" strain welding cable for flexibility 2)by pass disconnect switch 3)add a grounding cable from starter mounting bolt to frame I let you know what happenes
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| TomO | -- 07-17-2010 @ 8:54 AM |
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Here is how you can check out your starter circuit and cables. All tests are made with the starter operating and the ignition switch OFF. Connect the POS or + lead of your voltmeter to the cable connection on the starter and the COM or - lead of the meter to the NEG post of the battery. You should read .5 volts or less, while the starter is operating. If the reading is higher, you have excessive resistance in the circuit. The resistance can be caused by cables or the starter switch. To isolate the cause, check the voltage at the input to the starter switch, it should be less than .1 volts. If it is higher than .1 Volt, your problem is the connection to the battery or the cable. If the reading is less than .1 volt move the meter to the other side of the starter switch and repeat the test. An acceptable reading would be .1 volt higher than the previous test point. The ground circuit is tested the same way, except that the meter leads would be reversed and the maximum reading at the starter is .1 Volt. The 36 has longer cables than the later cars and it is very important that the correct size (0 gauge or larger) cables are used in the starter circuit. If your readings are within specs and the starter still doesn't crank the engine over fast enough, check the bushings for side play, the commutator and brushes for proper seating and cleanliness. You can also have the starter checked for proper current draw by someone who has the proper equipment. Tom
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| 36 Ford | -- 07-17-2010 @ 5:29 PM |
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ok up date replaced the wires to "0", cleaned all grounding contact points and added a cable from motor to frame. wow problem solved, spins perfect. I even added back in my disconnect switch, after i tested everything and no problems. thanks for all the advise
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| 37RAGTOPMAN | -- 08-18-2010 @ 9:55 AM |
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DID YOU TRY, turning the engine over by hand with out the starter to see if it is tight,to rule out the battery and starter, and the grounds, if it is tight it does not matter how many batterys and starters you have,,,you have to break in the ENGINE FIRST,!! if you can get it started, let it run for a hour,or more,,,, just keep a eye on it, USE A HOUSE FAN on a step ladder to aid in cooling,and keep checking it, I had a MODEL A, that I had to pull it to get running, but once started and broken in it was no problem after that,we used a rope and other car to pull it and used second gear, HOPE THIS HELPS,37RAGTOPMAN ,,and KEEP ON TRUCKIN,,,,,
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