<VV> AC Fast Idle Solenoid Repair - 1964-5

[William Hubbell]

Since the subject of AC fast idle solenoids was recently raised on this site, I’ll reprint here what I wrote on about repairing them. (previously posted on Corvair Center Forum).

This applies to 1962-65 vacuum electric units.

Re: Fast Idle Solenoid Rebuild
Posted by: whubbell ()
Date: April 05, 2022 08:44AM

Concerning repair and rebuilding of Corvair Fast Idle solenoids, this is something I have been messing round with for awhile. As I have explained elsewhere, there were five different versions used as follows:

*1962-63: vacuum-electric "pusher"
*1964-65: vacuum-electric "puller"
*Late 1965 (and replacement for all earlier): all electric "puller"
*1966 single arm all electric "puller"
*1967 double arm all electric "puller

The primary failure modes for the '62-'63 and '64-'65 versions are two-fold:
1) Solenoid coil failure (broken or shorted wire)
2) Valve failure

It is also possible for the vacuum diaphragm to fail, but that is rarely the case.

Regarding the solenoid failure, it is possible to remove the old solenoid wiring and rewind with new magnetic wiring. I have successfully done this using 28 AWG magnet wire. The procedure is as follows:
1) Remove coil from unit but leave it attached to the bakelite base
2) Remove tape from coil and unwind old wiring from coil.
3) Unsolder the ground wire from terminal on bakelite base.
4) Remove old section of insulated wire from bakelite base.
5) Insert a drill bit covered with either tape or shrink wrap sleeve into the hole in the center of the solenoid coil and chuck the bit into a variable speed electric drill.
6) Thread the end of your new magnet wire through the hole near the center of the bakelite base (the hole where the insulated wire passed through) and take one turn around the solenoid core.
7) Go to your bathroom and sit on the toilet (lid closed!)
8) Remove toilet paper from holder and replace with magnet wire coil
9) Holding drill and solenoid coil parallel to magnetic coil roll, slowly start drill and proceed to carefully wind wire onto solenoid core. Do your best lay out smooth and even windings, especially for first few layers. It doesn't have to be perfect. Continue winding until the coil is almost flush with the smaller bakelite disc.
10) Cut the wire from the coil, leaving an inch or two on the solenoid coil.
11) Move operations to your soldering table.
12) Slip the inner wire back through the hole and slide an insulated wire through.from the outside. Carefully remove a small amount of insulation from the tip of the inner magnet wire end and solder it to the insulated wire. Tape the soldered end and then apply tape to the coil wiring, leaving the outer end of the coil wire free.
13) Slip the outer wire through the hole on outer edge of bakelite base, remove insulation from tip, and solder to the grounding strap.
14) Attach a new terminal to the end of the insulated wire.

Regarding the valve failure - the valve is a small brass rod with a tapered point on one end and is swedged into a steel disc on the other end. The rod point can wear or the rod can break or come loose from the metal disc, any of which will result in failure. The '62-'63 rods are very small and difficult to replicate, but the '64-'65 rods are a standard 1/8" diameter brass rod which is easy to obtain and can be shaped using only an electric drill and a file or grindstone. However, this is a tedious process and I am looking for somebody who can machine these using a lathe or whatever.

I have too many photos to post, so instead I have created a Google album with all the photos here

Bill Hubbell,
President, Stock Corvair Group