'58 XK150 Dynalite Alternator swap question

[polandpdx]

This XK150 is set up negative ground, as is the Dynalite Alternator. It uses the original 3"OD pulley.
I trust the shop changed wiring per instructions to bypass the original voltage regulator.
At idle, the ammeter now shows ~25% discharge w/out lights and ~50% discharge with headlights on.
(Cibie Z-Beams w/ 55w halogen lamps).

At running speed of 2500 - 3000 crank RPM, the ammeter rises to neutral, but does not move to the positive charge side at all.

The interweb tubes believe an alternator won't put out below 2000 RPM at the alternator?
Is there something about the standard ammeter that needs to be rewired?

Thoughts?

I would like to be able to feed both the Z-beams and a pair of Cibie pencil beam driving lights using big direct wires and a slew of relays to take orders from existing switches. No hope unless I can get more amps into the system.

Steve Poland
polandpdx@gmail.com

 

[Whirilgig]

This XK150 is set up negative ground, as is the Dynalite Alternator. It uses the original 3"OD pulley.
I trust the shop changed wiring per instructions to bypass the original voltage regulator.
At idle, the ammeter now shows ~25% discharge w/out lights and ~50% discharge with headlights on.
(Cibie Z-Beams w/ 55w halogen lamps).

At running speed of 2500 - 3000 crank RPM, the ammeter rises to neutral, but does not move to the positive charge side at all.

The interweb tubes believe an alternator won't put out below 2000 RPM at the alternator?
Is there something about the standard ammeter that needs to be rewired?

Thoughts?

I would like to be able to feed both the Z-beams and a pair of Cibie pencil beam driving lights using big direct wires and a slew of relays to take orders from existing switches. No hope unless I can get more amps into the system.

Steve Poland
polandpdx@gmail.com

Wondering the same thing. I have a XK 150 that I changed to negative ground and am considering going to a alternator. Also in the PDX area. Did you make the conversion.

 

[LarryK]

Have you reset the voltage regulator? Even with pre negative ground a change out of generator or alternator might need a reset. since you are already negative ground you do not have to change amp/voltage gauge. Also, the old voltage regulator can be set to the needs of the lights. If the alternator has a built in regulator you will bypass old regulator

 

[KJP]

I did one of these on my '60 XK150, it was converted to negative ground. Mine had internal regulator, just follow the instructions to bypass old regulator, leave it there to look stock and it worked fine. Almost sounds like shop didnt bypass correctly if yours has internal regulator.

 

[Whirilgig]

I initially wanted to keep my XK 150 restoration original but after seeing the improvements of updated parts decided that I prefer a good runner over a trailer Queen. I put in a high torque starter, Dynalite distributor, Dynalite alternator, a single 12 volt battery and switched to negative ground. I kept all the old parts for future considerations if I ever sell. I still have the old Moss gearbox and overdrive but will go to a new five speed If the Moss fails. I always liked the oddball electric overdrives.

 

[KJP]

Yep, I got to the point with mine that while its nice to have a trailer queen and worry about if your inner fender bolts are the right size at a show, its also nice to be able to drive these cars reliably as well. I had the same mods in mine except for the distributor, had pertronix system under the cap.