Electrical question help

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DKnapp

Well-known member
I have a high compression "B" engine with Miller Overhead, having trouble starting it with a 6 volt starter. It turns over one rev and very slowly. The cables are getting hot too. It does not seem to have a very strong spark either.
I had it running fine on a test stand with 6 volts, but it is not starting since I put it in the Speedster. It has dual downdrafts and dual point distributor. Also thinking going to a Zenith and regular distributor.
And, I am thinking of buying a 12 volt starter so it will rev over faster. Do you know of a voltage reducer so I can run everything except the starter on 6 volts??
This is for my Speedster. Thanks for any help.

Dick Knapp, just turned 89 and would like to start enjoying this Speedster.
 

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If the cable are getting hot they are too small. I am using small cables on my 12 volt system to slow down the starter. The vendors sell cables for 6 volt systems or you could go to a marine supply store and buy the cables and ends to make up your own. West Marine may still have the tools in the store to crimp the ends.

Plus all connections must be bright and tight, including the ground that goes to the engine, probably via the transmission. A LiPo battery will put out more current because of less internal resistance and are about 1/3 the weight. But fix everything else first.

Measure the voltage across the battery while cranking over the engine. The battery may need replacing. Also measure the voltage at the stud on top of the starter switch against a good ground point on the engine while cranking the engine over, which should be the same as at the battery. This cranking can be done with the ignition off.
 
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Go to Just8ns (Ford Tractors) and you can find voltage reducers for converting from 6 to 12 volt. Item 8NE10306 may be what you need.
 
First thing I would try is, get some big fat 2/0 battery cables, hook them up to the battery, and connect the ground cable to a bolt on the starter. Remove the starter switch to expose the copper terminal button. Touch the negative cable to the starter terminal and see if it cranks at the right speed.

If it cranks correctly, the problem is in your wiring.
 
Take the spark plugs out and see if the starter will spin the motor over. If not, the high compression isn’t the issue.
 
Hello, as mentioned above posts, make sure the cables are heavy enough, the cables usually sold at car parts stores are too small, meant for 12 volt,also check battery ground to starter if not getting a good ground may cause run hot ,add a cable from frame to bell house see if that helps.
 
I have a couple questions for Dick.

When you say high compression Model-B. Exactly what is high compression? Most OHVs are not that high of compression. I have cranked 8:1 CR flathead Model-A/B engines on 6 volts. More than that and you often will experience sluggish cranking on the 6v.

Second, -is it the Starter cable, or the Ground cable that is getting hot? Since you mentioned it starting well on the test stand on 6 volts, my initial thought is it is not the cables per se' but so often the Ground wire (-from the Battery to the crossmember) while attached to the crossmember is the issue because the crossmember does not have a great connection between it and the L/S Frame Rail, and then it does not have a good connection between the Motor mounts, the Flywheel housing, and into the Starter case. Cranking with too small of diameter of a Starter cable generally allows the first or second revolution to be faster but quickly slows due to the resistance building.

I will close by saying if you are the speedster body builder, you are a remarkable wood craftsman!!
 
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