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gmc 353 to 12Volts


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I had 4 kits from not so Jolleyover a couple of months, 3 worked fine one failed after about 4 miles,had to get the GMC towed home as I didn't have the old dissy plate with me and the old points had pitted badly ,Phoned him up and he said to do all the checks which I had already done,I even swapped the parts from one GMC to he other and explained this to him so it was guaranteed the part was knackered .I asked if he could send out a replacement next day delivery as we were going to a show in 2 days, He said he would only replace once he received the broken part back and it was tested which ment over a week before getting a replacement . I had to pay for another and the return postage for the knackered part before he would dispatch a replacement.

In my opinion he personally wasn't very helpfull considering I brought 4 kits from him and a couple of his High output coils.

 

However the products once working are a great asset to the reliability of the GMC's, Jeep and Dodge.

Will be contacting http://www.pertronix.com I believe they do GMC kits and much cheaper than Frank Jolleys including the postage.

 

Regards

 

Steve

 

 

 

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thaks for the great info. But what about starter, it is also 6V ?

Maybe needs change :?

 

- Marko -

 

 

The Darlings buds of may

 

 

Hi Marko.

 

You can leave it in place if as most people do. I left my 6v in place and have been running on 12v for a long time with no problems at all. Just don't spin it over for to long at a time but you shouldn't to if you have upgraded to 12v as it should start pretty quickly.

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You can use any alternator. There isn't much curent draw on an old MV, depends if you want to put discrete gadget sockets on, in which case get a split charger and fit a second battery, that means you can play with toys and still start, a secondary use is you can self jump start. The problem is frst fitting to the brackets andd second which way round the belt will drive the alternator. A pre paid kit means all the problems are some one elses, bolt and go.

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Hi Marko

One could consider keeping the 6 Volts installation. I wouldnt convert mine for all in the world. What would be next? Aircondition and CD player? :|. No way- My GMC was born 6 Volt and will stay so - I like everything original and try to keep it that way when possible.

 

Out of curiosity, why would you like to convert? Is it a matter of spare parts?

 

Best regards

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Hi Marko

One could consider keeping the 6 Volts installation. I wouldnt convert mine for all in the world. What would be next? Aircondition and CD player? :|. No way- My GMC was born 6 Volt and will stay so - I like everything original and try to keep it that way when possible.

 

Out of curiosity, why would you like to convert? Is it a matter of spare parts?

 

Best regards

 

Hear hear, quite agree about keeping our trucks original, but this is how I came to change mine to 12volts, what is the point in having an original truck but is not safe to drive to shows ! I went to 12volts only for the reason of having proper modern bright head lights and good rear lights and brake lights oh and a bright orange flashing light no other reason

So that all other road users know I am infront and going slow, I try to avoid motorways as much as possible but this can still happen on dual carridgeways.

You sometimes here, now and again, that a historic MV was shunted up the back by another truck and I want to try and avoid this as the best I can...

 

All the best to one and all and Merry Christmas 31 days to go !!!!!!!!!!!!!!!!!!!!!!!!!

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Safety first - no argues against that. But someone did many years ago try to teach me some lessons in electrical formulas. Something I do remember is that Power=Voltage x Current. If we have 6 Volts we will just need the double up Current compared to 12 Volt but the power and in this case the light would be the same.

 

Like I said, my GMC has most of the electrical installations from the factory. But the rear lights is brand new and far from the original ones but still 6 Volts. I did make that compromise out of safety considerations. According to the danish regulations it would have been quite legal to stick to the original tail lights. Pictures on my www but only danish explanations available, sorry.

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I need a strong lights. 2 pcs extra lights to front ( 2 x 12V/55W/100W ) and worklights to rear ( ?W/but strong). And CB-radio.

Maybe it is possible to leave original 6V to engine and install a second alternator & battery (12V) to lights and other 12V appatus.

 

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Safety first - no argues against that. But someone did many years ago try to teach me some lessons in electrical formulas. Something I do remember is that Power=Voltage x Current. If we have 6 Volts we will just need the double up Current compared to 12 Volt but the power and in this case the light would be the same.

 

 

I will try to explain if you have a 6 volt 50Watt bulb it will draw about 8 Amps

If you have a 12 volt 50Watt bulb it will draw about 4 Amps

 

Watts divided by Volts gives Current

Current times Volts gives Watts

Watts divided by Current gives Volts

 

So if you fit larger Wattage lamps to your existing 6 volt system you increase the current more than it was, and could cause problems to the wiring and switches as they would be intended to work with the standard Wattage bulbs at 6 volts, if you change to 12 volts and up the wattage of the bulbs you should only get to about the same total current demand that it had at 6 volts with the standard type bulbs.

 

Hope this helps

 

R3

 

 

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  • 5 years later...

Mine starts on 6v in half a turn, even from cold. The guy I bought it from had rigged up a washer bottle in the cab with a manual pump (again from a windscreen washer ) which he then filled with petrol and pumped via a pipe into the carb.:cry: NOT A GOOD IDEA ! took it out as soon as I got it home. However, I start mine from cold by giving 30 pumps on the pedal, then full choke. As soon as it starts then choke in and hand throttle a quarter out. Works every time.:cheesy:

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Hello the answer is yes you could fit a 12 volt battery just to power the starter,a friend of mine has a gmc and he has 12 volts for starter and every thing else is 6 volts, just bear in mind that the 12 volt battery wont be getting any charge, but before you decide on 12 volts, I would have a closer look as to why the truck does not start on 6 volt very well, if its turning over slow check all of your earth wires, I have known the starter to draw so much voltage that there is not enough power left to give a good spark. Check your points and the gap, is the coil a good one, check the spark plugs gap, do you prime the fuel system and pump the trottle a few times before trying to start her up.Just a few pointers for you to look at Ive had 6 volt trucks and not had a problem.

 

all the best Howard

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