What should the voltage be at the coil when ignition on and engine running? I checked mine because I was having ignition related issues and found that it was only between 8.5 and 8.9 volts, I thought it should have 12volts. I know some cars in the ‘60s had a resistance wire to drop the voltage from 12V down to 6-8V but I don’t think my 1966 Toronado has such a wire or ballast resistor. Also, where does the wire run from the ignition switch, does it go directly to the coil or to somewhere else and then to the coil?,,,

 

The wiring diagram is included in the 1966 Oldsmobile Chassis Service Manual, I believe.

 

All points ignition systems have to have some voltage drop to avoid rapidly burning up the point set contacts.

This is the Toronado wiring diagram from the 1966 CSM. Follow the PINK wire from ignition switch. It goes to both the coil resistance wire and the fuse block.

 

I'd expect to see around 9 VDC. Does it run ok? It should be close to whatever the battery voltage is during cranking only.

Good luck!!!

 

Your voltage reading seems normal for a car with a resistance wire.

 

It has been running ok but have had times when it would hesitate off idle, die completely after a long warm up time, would start but run only a minute then die again,,,

 

Thanks to all who gave info concerning the voltage at coil; I have a HEI distributor and hi-output coil which I would like to install and try for a while, it's said I would need a 12V supply to the hi-output coil so not sure how to go about that, if in fact I do need the 12V, then run a separate wire from ignition switch bypassing the pink wire?,,,

 

Find a 12v switched power cavity in the fuse block. One that's hot only in START/RUN. Power the HEI off that.

 

There should be a terminal marked IGN in your fuse block, use that.

 

If you’re putting HEI in place of the points system in a ‘66, be sure to trace back beyond the end of the cloth covered resistance wire and bypass it, or you’ll have less than 12v switched to the HEI unit.

You’ll need to unwrap the wiring harness from the engine back to around the firewall grommet to find the place where the resistance wired is spliced in.

Then either remove it, or tape it off on both ends and swap in a wire in your choice of colors to feed the HEI. Pink is a common choice. Consider labeling the wire as “Switched 12v” just so if you or subsequent owner decides to go back to points, it’s obvious what you did.

Cheers
Chris

 

Why go to all that trouble to install that HEI on a hunch.
It's already established that your ignition system is working properly
Look at other things like timing or carb accelerator pump.
Make sure your points are in good condition and set them to 30 degrees dwell with a dwell meter.

 

Agree w/ Charlie. Be certain you're following the correct procedure for a tune-up - specifically outlined in your CSM.

I suggest you perform a thorough engine tune-up to specifications as outlined in your CSM and/or the label on your fan shroud. You should begin w/ relatively new (or brand new) correct spark plugs with the appropriate gap, a relatively new (or brand new) distributor rotor & cap, relatively new (or brand new) distributor contact points. Your coil should be relatively new (or brand new).

NOTE: Do not attempt to perform this procedure out of order. NOTE: Timing DOES NOT effect dwell - dwell effects your ability to achieve the correct timing. Follow the directions word-for-word including the disconnection of vacuum advance while performing the tune-up.

This must be performed in the following order from (1) to (3):

(1) Set dwell to specs
(2) Set timing to specs
(3) Adjust A/F mixture screws to highest achievable vacuum

 

If you replace the points ignition with an HEI, you should have the HEI recurved (change springs and weights, and change & adjust vacuum advance) to match the original distributor, or you will have sub optimal timing curve which may make the car run worse. Olds made many distributors, with the only differences being the weights and vacuum advance. They didn't waste money on developing/stocking/manufacturing them because they all will work the same on any engine. Same thing for Carbs. There is no bolt on ignition or carb that will work perfectly on any car. They all need to be tuned.