Does anyone have a troubleshooting process for stock 6V ignition in a 51 F1? Trying to get my dad's truck running as good as it looks, it would barely stay running, had to pedal it like mad but also keep choke part way closed, no power, and ran very hot.

I rebuilt and cleaned the carb today, no surprises there, everything looked ok. Timing seemed closed, at least static, but could not start it today to put on the timing light. How do I check the ignition coil and distributor?

Truck has been rewired using a 12V wiring harness kit, will this cause some problems? I understand that some wires are larger on a 6V circuit than 12V? Will anything be screwed up severely if we accidentally put in a 12V battery?

 

I can't answer some of your questions. But yes, the 6 volt system produces TWICE the amps of the 12 volt system, which is why some of the wires are quite heavy gauge. That means you may have melted some wires even using a 6 volt battery. If you used a 12 volt battery in a 6 volt system, you will probably have burned out any bulbs in use and possibly ruined your gauges.

Did you see smoke coming out of any of the wires? Letting the smoke out is a bad thing.

I will go out on a limb and say you may have ruined your coil if it is a 6 volt coil. I think your running problem may be related to over powering the coil.

 

I will try to help as much as possible. You said you have a timing light. Hook it to number 1 cylinder (front passenger side) and crank engine while someone watches the light. If it flashes you have spark going to the plug. There is a pointer mounted to the front of the engine just below the distributor, as you look at the crankshaft pulley from the front it is at about 11:00 o'clock. There is a rivet or mark on the pulley, the pointer and pulley mark should be close to alignment when you crank while pointing the timing light at the pulley ( this is not the way you set the timing but is close enough to get it running). If the timing light does not flash in above test. Use a test light (if 12V light it will be dim) or volt meter and test FOR A POSITIVE GROUND SYSTEM between the negative side of the coil and the block with the key on, you should show 6V. If negative ground you check between the + coil terminal and the block. If this checks ok the coil may not be getting continuity through the points. Remove the cap and look at the contact surfaces on the points, if they are dirty or corroded you can use fine sandpaper folded in half or a small file to clean them enough to get running.

Give these ideas a try but, the problem sounds more to me like carburetion. Did you make sure fuel was flowing to the carb after the overhaul?

Good luck.

 

Are you saying the truck is 6v, but was rewired with a 12v harness?

 

Yes, truck is 6V, with 12V harness. Supposedly the builder consulted with the shop that sold the harness, could not get 6V harness in timely manner, but was "supposed to be ok". (Unfortunately we cannot recommend this builder to anyone else.) Harness has modern fuse block with the new style fuses, so don't know if anything was/will get cooked/melted.

I will put the timing light on the truck next time I go see it to check. Also going to try to check the gap on the points. Also investing in a quality digital multi-meter.

Didn't find anything plugged in the carb, but will also check fuel pump output to make sure it's ok, but I think it's new or a reman.

And Joe, none of the smoke escaped from the wires

 

You might be OK, depends on the new harness. The wires from the generator to the voltage reg are a separate bundle, and may have been retained? If so they are 6v-appropriate. The difference in the headlight wiring is probably only one wire size, maybe you can avoid using them until you verify. Any other wiring is probably not going to smoke off.

Is this a 6 or a V8? Has it been sitting a long time? (more than a month) It's a good idea to run such an engine off of a "supplemental gas tank", like a boat tank or a gallon can securely attached somewhere. The fuel systems are frequently plugged up with rust and dirt, this eliminates sucking it thru the whole system. If the fuel pump is suspect, you can run a "***** bag" setup that gravity feeds the carb and bypasses the pump.

The usual culprit in the ignition is the condenser. Modern replacement 6v condensers are crap. Also the wire from the coil to the distributor frequently frays underneath the points plate, and shorts out the points.

 

Sounds pretty much like the problems.I was having with my stock '49 F-2 recently. Installed an condenser and all is good.

 

Do you have a multi-meter....and do you know how to use one? You can test most of the components such as the coil, and the function of the ignition points. Those old condensers (that the automotive name for a capacitor) do sometimes give up the ghost. Some multi-meters can test a condenser too. Let us know...I can walk you through some of the tests.

You indicated that the truck was re-wired with a modern harness, but the 6v system was retained. I'm going to assume that it worked at some point. I'll also assume that the ignition circuit is essentially original.....maybe the wires are new, but possibly map to the original schematic.

Hooking up a 12v battery could peg on the gauges to their full travel. If the lights were left off, the bulbs may have survived. Is it re-wired to the original positive ground. The amp-meter gauge would be unaffected, but the fuel gauge may have gone past full scale...hopefully the tank was low on fuel. The oil pressure gauge may have taken a hit....but again, it may have been reading double the scale....and if lucky the gauge is fine.

Dan

 

Was the positive terminal for the 12v battery attached to the ground strap? How is the 6v battery attached?

 

Hi Chad,


Obviously your problem is fuel, spark or a combination of the two.


Have you considered completing the 12v conversion on the truck?


Seems like you have ruled out the fuel (carb rebuild). Perhaps if you completed the 12v conversion you could eliminate the majority of the other problems?


Bob

 

First off, I have no confirmation that we actually put in a 12V battery. My dad bought a 6V, and the part number checks to a 6V, but when I put my el cheapo inaccurate multimeter on it, it didn't say 6V, that is the only reason I am asking what could happen. Going to put a quality digital multimeter on it and verify before putting the battery back in.

Yes I know the truck is positive ground. Theoretical question though, what happens if you hook the battery up backwards?

Dad wants to keep it 6V. Truck was bought as an incomplete project, but unfortunately all the wiring harness was out of it already, thus the new harness, and my dad wasn't technical enough to know what he was buying at the time.

Gas tank was all cleaned out, and new fuel lines on fresh engine rebuild, so minimal chance for crud. Screen is in place in the glass fuel bowl. Is there supposed to be a secondary filter too or just the screen?

 

Nothing permanent.

Some of the gauges might not work properly. Some coils don't work right, but they still work. The starter turns the same.

 

I have a little more time to night to participate in this discussion.

I drove my F-2 for some time with the polarity reversed, nothing happened.

To add to my condenser problem, I had to jump start it with a 12 volt truck, which I've done plenty of times but I think this time it fried the condenser. If you truck was operated at all with a 12 volt battery but with the stock 6 volt condenser you might have fried it. Just a thought.

Bob

 

When jumping a six volt truck with a 12v source, jump directly to the starter side of the start relay. No need to put 12V into the rest of the system. Set up the truck, brake set, out of gear, ignition switch on and hit the cable to starter cable lug with 12V. The engine will turn over and start and run on six volts

 

Ok, confirmed that truck has not seen a 12V battery. Ignition coil was pooched, possibly from forgetting key in on position. Could not try a new coil yesterday yet, as the only parts store that stocks them sold his last one yesterday morning, so waiting until later this week. Did replace the puny 4 AWG battery cables with 1 AWG (largest on the shelf).

Condenser measured a bit low to spec, but it was hard to measure correctly, and without a coil and without being able to crank over the engine on battery hard to verify if it's sparking correctly. Condenser and points are new, with minimal run time.

However, the truck will not turn over. Is the battery (new) not charged up enough? Shows 6.3V on the meter. Is it safe to check current through a multimeter? Should we be checking out the solenoid? Starter? Engine feels "normal" for a rebuilt engine (compared to a 351) when turning over with Johnson bar on the crank bolt.