NOTES ON REPLACING JAVELIN/JUPITER DYNAMO BY AN ALTERNATOR

Suggested Lucas alternators:—

ACR15             25amp Use      44/0.30 gauge wire

ACR16             30amp             65/0.30

ACR17            33amp             75/0.30

ACR18             40amp             84/0.30

ACR23/25      60amp             120/0.30

ACR15 is a direct replacement for the dynamo. ACR16&17 give a higher output for normal use. ACR18 to 25 are high output for special applications)

A special mounting bracket will need to be fabricated. The vehicle must he negative earth polarity. The Jav/Jup are positive earth and their polarity must be reversed.

Reversing Polarity

This is quite simple. You must first check that you have no accessories which require positive polarity. In all probability a wireless will be the only problem on Jav/Jup unless non-standard things like electronic rev-counters or transistor ignition are fitted.

First, swap the battery leads around i.e. put the positive (earthed) lead on the negative terminal — you will need to change the terminal clamps on the leads to fit the battery posts.

Second, swap the leads to the coil terminals marked either CB/SW or +/-

Third, take the wires off the “D” & “F” terminals of the voltage control unit on the bulkhead.

Fourth, (not required if you are never going to swap the dynamo back in again). Take the wire which was on the “F” terminal and brush it. against either the “B” or “A” terminal on the voltage control box several times. NOTE this will result in a flash as the wire touches the terminal, this is normal and reverses the polarity of the dynamo.

Fifthly, replace the “D” & “F” wires to the terminals where you found them to begin with.

Fitting the alternator.

Remove the dynamo and insulate the thicker of the two wires which is now not needed. Make sure you mount- the alternator pulley in line with the water pump and crankshaft pulleys.

Connect the thin wire previously on the dynamo to-the alternator terminal marked “IND”. Then connect from one of the large +ve terminals on the alternator to the live starter solenoid terminal using the wire size shown above. The starter solenoid is on the bulkhead of the Jup and under the floor of the Jav. The live solenoid terminal is the one which has the main cable from the battery attached. (If the alternator happens to be an early one which has two smaller terminals marked - & +, earth the - terminal and connect the + to the solenoid together with the 1arge positive terminal.)

At- the voltage control box, disconnect the thinner of the two wires from the “D” terminal and the wire from he “F”. Join these two together with a screw connector and insulate.

The control box could be removed (but it does make a useful terminal block). In this case wires from the “D” & “E” terminals must be removed and insulated separately. The wires from the “A” & “Al” terminals should be removed and joined with a screw connector and insulated.

KC Notes.

It is worth putting an isolator switch in the circuit between battery and starter. On the Jav this can be put next to the starter solenoid with a hole through the floor and, on the Jup you can put it on the floor under the gear lever or any other either convenient or concealed position (depending on whether the switch is for safety or security ). Note that this switch should not be opened with the engine running as the alternator diodes will blow. If your clock is still working, you will need to run a separate fused circuit to it.  I have an A133/55 Lucas fitted to the Javelin suitable for Winter Rally driving. I have fitted the pulley from a Jowett dynamo to the alternators, on the Jup the fins were ground off and the pulley fitted to the original alternator fins to provide more cooling.