swaping 8v71 motor that came from a 12 volt bus

[johnjem]

swaping a 8v71 motor that came out of a 1967 gm 4107 12 volt engine and tranny!!>
the bus it is going in is a gmc 1970 4905 <24volt> system  will all sensors and alternater,starter,and all other electrical components have to be swaped over !  to the 24 volt motor ps i know the starter and alternater  but what else would u think i need to swap over need to make a list ! also so what other things do i need to worry or fix befor i get done and greasy? thanks john

[4106-123]

you will have to change all the senders to 24volts such as temp and oil

[DrivingMissLazy]

Jake Brake!
Richard

swaping a 8v71 motor that came out of a 1967 gm 4107 12 volt engine and tranny!!>
the bus it is going in is a gmc 1970 4905 <24volt> system  will all sensors and alternater,starter,and all other electrical components have to be swaped over !  to the 24 volt motor ps i know the starter and alternater  but what else would u think i need to swap over need to make a list ! also so what other things do i need to worry or fix befor i get done and greasy? thanks john

[johnjem]

no jakes on the 12 volt motor so i am taking then off the 24 volt motor <thanks got that on my list now thank u?completey for got about the jakes

[Stan]

If these motors have an emergency shut down on the air horn, you will have to change the solenoid that trips it.
If the Skinner valves are mounted on the engine, they will also have to be moved.

[johnjem]

good tip thanks stan

[gus]

Anything electric will have to be changed. You might get away with using the 12v starter but only if it isn't cranked more than a couple of seconds at a time-still a risk.

At least you get a break on the wiring, it is designed for twice the amps used for a 24v system.

[Don4107]

Not trying to be a smart you know what, but I would say anything that has a wire connected to it should be saved from the old engine. 

If the donor engine is running or has oil in it, I would go for a oil sample test to get a better idea if it is worth the work.  Just good insurance.

Good luck

[Stan]

With reference to changing anything electrical: Switches are not voltage sensitive (12 - 24) so the shut down switches for low oil, high water temp. are OK, also the fuel pressure switch is OK. Senders for oil pressure and water temperature may have to be changes. Depending on the gauges in your dash panel, some 24 volt gauges use the same sender as a 12 volt gauge. The starter and alternator definitely have to be changed.

[gus]

Yeah, I agree. I wasn't thinking about switches, they actually have to carry fewer amps with 24v.

On/off sensors that work on pressure only will work ok but resistance sensors will not work properly since I=E/R and you are doubling E.

If anything has a heating element (Resistance) it will not work properly and probably burn out, this includes light bulbs.

[Stan]

gus: Vehicle gauges don't usually work on raw voltage. If they did, they would fluctuate with the battery voltage and alternator output. The regulated voltage may be as low as six volts and will work fine on any voltage above that.  Gauges for a nominal 24 volt system may not work on a 12 volt system if the regulated voltage is above 12 volts. Many gauges use a simple voltage divider system by using balanced coils. Away back when, gauge designers used a vibrating reed as a gauge voltage regulator in vehicles built in the 1930s. Cheap gauges (made in China from the auto parts store) are just that - cheap.

johnjem: For the few minutes work involved, just change the oil and temperature senders when the engine is out. Be sure that you know which one is the temperature sender and which one is the engine shut down switch.

[gus]

Stan,

I know that is true on many vehicles, called a voltage limiter on some, but so far I haven't found any on my 4104.  I have been into the panel wiring many times including installing a voltmeter and rewiring the inst lights. I'll have another look at the schematic, it may be hidden somewhere in the side panel.

[Stan]

Gus: If your 4104 still has the old, heavy Delco or SW gauges they use a balanced coil setup internal to the meter. It is common on these meters to sit wherever they were reading before the power was turned off. Internally, they look like an electric motor, nothing like a d'Arsonval movement which is in cheap gauges.

[gus]

Stan,

The oil press and coolant temp gages were new when I got the bus two years ago, all the rest are original except the VM I just added, none stay on last readings.

The oil press is steady and the coolant temp follows the shutter, about 10* up and down.

The original Generator gage does nothing that makes any sense but it was converted to a 160a truck alternator when I got it. That's the reason I installed the VM.